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  • 2020-2023
  • 1985-1989  (68)
  • 1965-1969  (4)
  • 1989  (36)
  • 1986  (32)
  • 1966  (4)
  • Cat
  • 1
    ISSN: 1573-0832
    Keywords: Sporotrichosis ; Sporothrix schenckii ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The isolation of Sporothrix schenckii from a female European cat it is described. The cat showed lengthened alopecic areas, with prominent nodules in the external surface of the thighs and abdomen. A mycological and histopathological studies of the lesions were carried out. The lesions resolved under treatment with 20% potassium iodide in doses of 0'1 ml/kg oral route in a 8 weeks period.
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  • 2
    ISSN: 1432-0568
    Keywords: Lateral reticular nucleus ; Cerebellar nuclei ; Retrograde transport of WGA-HRP ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The cerebellar nuclear projection from the lateral reticular nucleus (NRL) was studied in 29 cats by means of retrograde axonal transport after implantation of the crystalline wheat germ agglutinin-horseradish peroxidase (WGA-HRP) complex in the cerebellar nuclei. It was confirmed that all the cerebellar nuclei receive afferent fibres from the NRL with the strongest termination in the ipsilateral interposed nuclei. In addition, these experiments give evidence of a previously unrecognized topical pattern in the projection to the interposed nuclei, arranged according to the same principle as in the projection to the immediately overlying cerebellar cortex. Thus, the anterior interposed nucleus receives fibres from all parts of the main NRL, its rostral part especially from laterally situated neurons, while subsequent more caudal parts from more medially situated neurons, while the posterior interposed nucleus receives fibres mainly from the dorsomedial part of the main NRL. The cerebellar nuclear projection to the NRL was investigated in 15 cats using retrograde transport after ventral microiontophoretical ejections of the WGA-HRP complex in the main NRL. The contralateral rostral fastigial nucleus was confirmed as the main origin of this projection, but projecting neurons were, in addition, discovered rostrally in the anterior interposed and dentate nuclei on the same side. No topical differences could be observed following ejections in different parts of the NRL; the majority of the projecting neurons were always concentrated along the ventral and lateral borders of the fastigial nucleus and in the adjacent medial part of the anterior interposed nucleus.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 79 (1989), S. 330-332 
    ISSN: 1432-0533
    Keywords: Sphingomyelinosis ; Neuropathology ; Histochemistry ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This report presents the clinical, morphological and biochemical findings on an 11-month-old female Siamese cat with neurovisceral sphingomyelinosis. Gross pathological features and histochemical findings are compared with the human disease counterpart and the previously described animal models. Hepatomegaly was observed while splenomegaly was not. Although sphingomyelin in liver and spleen was biochemically elevated, histochemical results in this case were slightly different from those previously recorded in human and feline Niemann-Pick disease. These results suggest that this feline case might be a different type of animal Niemann-Pick disease to that reported previously.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Annals of hematology 58 (1989), S. 195-199 
    ISSN: 1432-0584
    Keywords: Cytochemistry ; Blood ; Bone marrow ; Leukocytes ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Blood and bone marrow cells of ten clinically healthy cats were stained for alkaline phosphatase (ALP), peroxidase (PO), chloroacetate esterase (CAE), alpha-naphthyl butyrate esterase (NBE), sudanophilia, and periodic acid-Schiff (PAS) reaction. Mature neutrophils in blood and bone marrow were devoid of ALP and NBE, but exhibited modest to strong PO, CAE, sudanophilia, and PAS reaction. In bone marrow, sudanophilia, PO, and CAE were prominent at the promyelocyte stage and diminished with cellular differentiation and maturation, while PAS reactivity increased with cell maturation usually from the myelocyte stage onwards. Myeloblasts were negative for all cytochemical reactions, but some large unidentifiable cells reacted strongly for ALP. Eosinophils were slightly reactive for ALP, CAE, and PAS, but not for PO, sudanophilia, and NBE. Basophil granules stained strongly for CAE, revealed PAS positivity, and stained negatively for PO, NBE, ALP, and sudanophilia. Slight ALP activity was detected in the intergranular cytoplasm of basophils. Lymphocytes and monocytes, with few exceptions, stained negatively. An occasional lymphocyte revealed slight globular NBE activity (NaF-resistant) and diffuse PAS reaction, while an occasional monocyte contained a few PO-positive and sudanophilic granules. Monocytes reacted modestly, whereas bone marrow macrophages reacted strongly for NBE (NaF-sensitive). Cells of the erythroid series stained negatively for all cytochemical reactions, megakaryocytes were PAS-positive, and platelets gave positive reactions for PAS and CAE.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 75 (1989), S. 265-279 
    ISSN: 1432-1106
    Keywords: Rostral interstitial nucleus of the MLF ; Interstitial nucleus of Cajal ; Spinal cord ; Motoneurons ; Neck muscles ; Axial muscles ; Vertical eye and head movements ; Autoradiography ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Eye and head movements are strongly interconnected, because they both play an important role in accurately determining the direction of the visual field. The rostral brainstem includes two areas which contain neurons that participate in the control of both movement and position of the head and eyes. These regions are the caudal third of Field H of Forel, including the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) and the interstitial nucleus of Cajal with adjacent reticular formation (INC-RF). Lesions in the caudal Field H of Forel in monkey and man result in vertical gaze paralysis. Head tilt to the opposite side and inability to maintain vertical eye position follow lesions in the INC-RF in cat and monkey. Projections from these areas to extraocular motoneurons has previously been observed. We reported a study of the location of neurons in Field H of Forel and INC-RF that project to spinal cord in cat. The distribution of these fiber projections to the spinal cord are described. The results indicate that: 1. Unlike the neurons projecting to the extra-ocular muscle motoneurons, the major portion of the spinally projecting neurons are not located in the riMLF or INC proper but in adjacent areas, i.e. the ventral and lateral parts of the caudal third of the Field H of Forel and in the INCRF. A few neurons were also found in the nucleus of the posterior commissure and ventrally adjoining reticular formation. 2. Neurons in caudal Field H of Forel project, via the ventral part of the ventral funiculus, to the lateral part of the upper cervical ventral horn. This area includes the laterally located motoneuronal cell groups, innervating cleidomastoid, clavotrapezius and splenius motoneurons. At lower cervical levels labeled fibers are distributed to the medial part of the ventral horn. Projections from the caudal Field H of Forel to thoracic or more caudal spinal levels are sparse. 3. Neurons in the INC-RF, together with a few neurons in the area of the nucleus of the posterior commissure, project bilaterally to the medial part of the upper cervical ventral horn, via the dorsal part of the ventral funiculus. This area includes motoneurons innervating prevertebral flexor muscles and some of the motoneurons of the biventer cervicis and complexus muscles. Further caudally, labeled fibers are distributed to the medial part of the ventral horn (laminae VIII and adjoining VII) similar to the projections of Field H of Forel. A few INC-RF projections were observed to low thoracic and lumbosacral levels. It is argued that the neurons in the caudal Field H of Forel, which project to the spinal cord are especially involved in the control of those fast vertical head movements which occur in conjunction with saccadic eye movements. In contrast the INC-RF projections to the spinal cord are responsible for slower, smaller movements controlling the position of the head in the vertical plane.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 75 (1989), S. 639-643 
    ISSN: 1432-1106
    Keywords: Motor cortex ; Somaesthetic responses ; Spinothalamic system ; Intracellular recording ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Evidence is presented that in the cat, the spinothalamic system contributes to short latency somaesthetic responses in motor cortex efferent cells. Intracellular recordings performed on identified pyramidal tract cells and corticospinal cells show that these cells are still activated and/or inhibited from the periphery after a set of central nervous lesions leaving intact only the ventral half of the spinal cord. The responses were attributed to the spinothalamic system. The ascending system is activated through collaterals of afferent fibres running in the dorsal columns of the spinal cord. This peripheral link to the motor cortex might participate in updating the motor command on the basis of information feedback from the periphery.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 76 (1989), S. 182-186 
    ISSN: 1432-1106
    Keywords: Retinal ganglion cells ; Orientation bias ; Receptive field centre ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary For cat retinal ganglion cells whose receptive field centres were distributed in specified sections of the left visual field, the deviations of the major axis from the radial, horizontal, and circumferential directions were determined. The percentage of cells with deviations within ± 20° from the radial, horizontal, and circumferential directions were, respectively, 33%, 68%, 16%. In addition, comparison between values of deviation from the horizontal direction for cells located at eccentricities of 10° and 20° from the area centralis showed a statistically significant trend: the bias for the horizontal increased with eccentricity.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 76 (1989), S. 519-529 
    ISSN: 1432-1106
    Keywords: Pontine tegmentum ; Cholinergic neurons ; Single units ; Sleep-waking states ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A total of 260 neurons were recorded in the rostral pontine tegmentum of freely moving cats during the sleep-waking cycle. Of these, 207 neurons (80%) were located in the dorsal pontine tegmentum containing monoaminergic and choline acetyltransferase (ChAT)-immunoreactive, or cholinergic neurons. In addition to presumably monoaminergic PS-off cells (n = 51) showing a cessation of discharge during paradoxical sleep (PS) and presumably cholinergic PGO-on cells (n = 40) exhibiting a burst of discharge just prior to and during ponto-geniculo-occipital (PGO) waves, we observed tonic (n = 108) and phasic (n = 61) neurons exhibiting, respectively, tonic and phasic patterns of discharge during wakefulness and/or paradoxical sleep. Of 87 tonic cells histologically localized in the dorsal pontine tegmentum rich in cholinergic neurons, 46 cells (53%) were identified as giving rise to ascending projections either to the intralaminar thalamic complex (n = 26) or to the ventrolateral posterior hypothalamus (n = 13) or to both (n = 9). Two types of tonic neurons were distinguished: 1) tonic type I neurons (n = 28), showing a tonic pattern and high rates of discharge during both waking and paradoxical sleep as compaired with slow wave sleep; and 2) tonic type II neurons (n = 20), exhibiting a tonic pattern of discharge highly specific to the periods of paradoxical sleep. Tonic type I neurons were further divided into two subclasses on the basis of discharge rates during waking: a) rapid (Type I-R; n = 17); and b) slow (Type I-S; n = 11) units with a discharge frequency of more than 12 spikes/s or less than 5 spikes/s, respectively. Like monoaminergic PS-off and cholinergic PGO-on cells, both tonic type II and type I-S cells were characterized by a long spike duration (median: 3.3 and 3.5 ms), as well as by a slow conduction velocity (median: 1.8 and 1.7 m/s). In the light of these data, we discuss the possible cholinergic nature and functional significance of these ascending tonic neurons in the generation of neocortical electroencephalographic desynchronization occurring during waking and paradoxical sleep.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 77 (1989), S. 271-282 
    ISSN: 1432-1106
    Keywords: Red nucleus ; Motor initiation ; Single-unit activity ; Reaction time ; Delayed movement ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The activity of 98 Red Nucleus neurons was recorded in 3 cats operantly conditioned to perform a ballistic forelimb flexion movement triggered after a brief sound in a simple Reaction Time condition, or Delayed after the same sound in the presence of a tone cue. Fifty-eight task related neurons presented changes of activity in either one or both conditions. Forty-four of them were studied quantitatively and classified in 3 categories: 1) only 16% of the units presented similar changes of firing preceding the triggered or delayed movement; 2) most units (55%) presented different changes of activity in the two conditions: in the Delayed condition, the activation occurred earlier before the movement, and/or the change in magnitude was reduced or the pattern of activity was modified; 3) moreover, for 29% of the units, the change of activity observed before movement in the Reaction Time condition was severely reduced or even absent in the Delayed condition. For some of these neurons a building-up of activity was observed very early in the Reaction Time condition, during the preparatory period, well before the occurrence of the conditioned stimulus. These results show that the Red Nucleus activity preceding a movement is clearly dependent on its initiation conditions. The distinct patterns of unit firing observed in the Reaction Time condition and in the Delayed condition are tentatively related to the different preparation and initiation constraints determined by the behavioral conditions.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 77 (1989), S. 577-584 
    ISSN: 1432-1106
    Keywords: Motoneuron pool ; Inhibition ; Monosynaptic reflex ; Recruitment level ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The motoneurons to the Soleus muscle in the decerebrate cat were activated by the crossed extensor reflex, elicited by stimulation of the contralateral common peroneal (CP) nerve. Monosynaptic reflexes were obtained from the Soleus motoneuron pool by stimulation of the cut L7-S1 dorsal roots. The amplitude of the reflex increased approximately linearly with the recruitment level of the motoneuron pool. Tonic postsynaptic inhibition was induced in the Soleus moto-neuron pool by repetitive antidromic stimulation of the Lateral Gastrocnemius (LG) and Medial Gastrocnemius (MG) nerves at a rate of 17–47 stimuli/s. This reduced the size of the monosynaptic reflex at rest by at least 40%. However, when the motoneurons were active, the amplitude of the monosynaptic reflex obtained during repetitive stimulation of the LG-MG nerve increased with the recruitment level along the same curve as the control reflexes. Thus, tonic postsynaptic inhibition of the motoneurons per se cannot control the amplitude of the monosynaptic reflex independently of the recruitment level of the motoneuron pool. These experimental results verify predictions from computer simulations and suggest by exclusion that presynaptic inhibition is needed to control the amplitude of the monosynaptic reflex independently of the recruitment level of the motor pool.
    Type of Medium: Electronic Resource
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 74 (1989), S. 220-226 
    ISSN: 1432-1106
    Keywords: Cat ; Medial geniculate body ; Hearing ; Tonotopic organization ; Single unit recording
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The tonotopic organization observed in the present study for the pars lateralis (LV) of the medial geniculate body (MGB) in nitrous oxide anesthetized cats is generally consistent with that previously reported under barbiturate anesthesia. The present data, however, provide evidence for local deviations in characteristic frequency (CF) using appropriate sampling procedures of single units. Although the majority of pairs of units recorded simultaneously with the same microelectrode showed comparable CFs, a few pairs of such neighbouring units displayed CF disparities of up to 1.5 octaves. In addition, some units characterized by an elevated threshold had a CF deviating significantly from the general CF progression observed for the majority of units having low thresholds. This study points out the influence of the sampling procedure on the quality of the tonotopic organization observed in the MGB in addition to a possible effect of the level of anesthesia.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 76 (1989), S. 307-314 
    ISSN: 1432-1106
    Keywords: Moving stimuli ; Orientation specificity ; Preferred axes ; Spot-response-axis ; Striate cortex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The responses of 82 simple cells and 41 complex cells in area 17 of anesthetized and paralysed cats were examined with light bars of different length. For 84% of the simple cells and 66% of the complex cells the preferred axis of orientation of a stationary flashing long bar (orientational selectivity) and the preferred axis of movement of a small spot were parallel. As a consequence, the axis of maximal response to a moving light spot was mostly orthogonal to the optimal axis of a moving bar. Thus, a single cell responds to two perpendicular axes of preferred movement one for a long bar and one for a light spot, respectively. For both axes independent direction preferences could be distinguished. Additional preferred axes of movement between the two orthogonal extremes could be found with moving bars of intermediate lengths. This can be explained by the fact that cells with a pronounced response to a moving spot showed a strong tendency for intermediate bar length to elicit responses consisting of a superposition of both components. Therefore, decreasing bar length resulted in a gradual rotation of the preferred direction of movement from orthogonal to parallel with respect to the orientational axis, rather than to a mere widening of the tuning curve. Accordingly, the change in orientation selectivity with decreasing bar length is a regular transition from the orientation dependent response to a response type that depends only on the movement axis of the spot. Thus, in a simple model, the resulting response characteristic can be interpreted as an average of both components weighted according to the length of the stimulus.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 77 (1989), S. 94-102 
    ISSN: 1432-1106
    Keywords: Eye movement ; Brainstem ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study maps the eye movements evoked by microstimulations in the medulla of 9 alert cats. Trains of square waves (20 μA amplitude, 0.2 msec duration, 200 Hz) were delivered through glass-covered tungsten microelectrodes (0.5–1 MΩ). Movements of both eyes were recorded by the magnetic field/eye coil technique. Stimulation of the prepositus hypoglossi nucleus (PH) evoked nystagmus with ipsilaterally-directed slow phases followed by after-nystagmus with contralaterally-directed slow phases. Stimulation of the medial vestibular nucleus (MVN) induced nystagmus whose slow phases were more often ipsilaterally-directed but at time contralaterally-directed. At nearly all sites where we stimulated the reticular formation underlying prepositus and vestibular nuclei (from P4.5 to P12), we recorded versional conjugate movements. They were most often ipsilaterally-directed. Some microstimulations in the region of the medial longitudinal fasciculus evoked recentering eye movements: regardless of the initial position of the gaze (to the left as well as to the right), microstimulations given at the same place induced a movement of both eyes toward their neutral position. The amplitude of this movement was proportional to the eccentricity of the pre-stimulation position of the gaze.
    Type of Medium: Electronic Resource
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  • 14
    ISSN: 1432-1106
    Keywords: Pharyngeal vagus nerve ; Pharyngeal glossopharyngeal nerve ; Nucleus ambiguus ; Retrofacial nucleus ; Lateral reticular formation ; Nucleus of solitary tract ; Alaminar spinal trigeminal nucleus ; Horseradish peroxidase ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The central distributions of efferent and afferent components of the pharyngeal branches of the vagus (PH-X) and glossopharyngeal (PH-IX) nerves in the cat were studied by soaking their central cut ends in a horseradish peroxidase (HRP) solution. HRP-labelled PH-X neurones were distributed ipsilaterally in the rostral part of the nucleus ambiguus (NA) and the retrofacial nucleus (RFN); HRP-labelled PH-IX neurones were found in the ipsilateral RFN and the bulbopontine lateral reticular formation (RF). Vagal pharyngeal neurones constituted a large population of brainstem motoneurones. The population of HRP-labelled glossopharyngeal neurones was divided into two components. Indeed, on the basis of their location and somal morphology, the most ventral cells were identified as cranial motoneurones and those scattered in the lateral RF as parasympathetic preganglionic neurones. Application of HRP to the PH-IX nerve resulted also in the labelling of fibres and terminals in the alaminar spinal trigeminal nucleus and the nucleus of the solitary tract (NTS). The afferent fibres entered the lateral medulla with the glossopharyngeal roots, ran dorsomedially, then turned caudally toward the NTS and the caudal part of the alaminar spinal trigeminal motor (V) nucleus. In the NTS, labelled fibres ran mainly along the solitary tract, projecting to terminals in the dorsal and dorsolateral nuclei of the NTS.
    Type of Medium: Electronic Resource
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  • 15
    ISSN: 1432-1106
    Keywords: Lateral geniculate nucleus ; Optic tract ; Sustained cells ; Transient cells ; Temporal luminance modulation ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We recorded the response of sustained (X) and transient (Y) cells in the cat lateral geniculate nucleus (LGN) and optic tract to a stationary spot while the spot luminance was increased and decreased with a constant rate (linear luminance functions), or modulated sinusoidally. The spot filled the receptive field center, and was surrounded by an annulus of fixed luminance. The LGN X cells seemed to perform a differentiation-like operation in the time domain at slow temporal modulations, giving information about rate of luminance change. To the linear luminance functions the cells responded with a constant firing rate. The on-center cells were activated during increasing luminance, the off-center cells during decreasing luminance. This firing rate increased monotonically with rate of luminance change. To low-frequency sinusoidal modulations the cells had a marked negative phase shift. The response of the LGN Y cells had a transient component shortly after the luminance started to increase (on-center cells) or decrease (off-center cells), followed by a secondary, gradually changing component. The peak of the transient component occurred on average when the response of the X cells increased most rapidly. To low-frequency sinusoidal modulation the average negative phase shift of this peak was twice the average of the X cells. The Y system could accordingly provide information about rate of change in the response of the X system. In the optic tract the X fiber response resembled the LGN X cell response in most respects. The Y fibers had only a weak transient response component, so this component was accentuated in the thalamic relay. Also the sensitivity for rate of luminance change was increased in LGN.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 74 (1989), S. 131-138 
    ISSN: 1432-1106
    Keywords: Phrenic motoneurons ; Intracellular recording ; Interactions ; Recurrent EPSPs ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Intracellular recordings were made from 220 Phrenic Motoneurons (PM) in anaesthetized, spontaneously breathing cats, deafferented from C3 to C7, in order to look for somatic events related to the Recurrent Responses (RR) evoked in PM axons by repetitive stimulation of the phrenic nerve. RR appear sporadically at a constant latency, originate from a spinal nicotinic mechanism and can be evoked in a PM without the presence of an antidromic volley in its axon (Khatib et al. 1986). 2. Using stimuli effective for eliciting RR in axons, we failed to observe intracellularly somatic events corresponding to RR after the occurence of an antidromic action potential. RR were observed extracellularly in two cases, but in both cases the recording originated from axons. 3. We attempted to elicit somatic RR without a preceding antidromic action potential, using either parathreshold stimulation of the impaled PM, or suprathreshold stimulation of a phrenic strand which excluded the axon of the impaled PM. In both cases, RR-like events, with very stable latencies, appeared sporadically in 4/142 and 2/15 PMs respectively. 4. Parathreshold stimuli or stimulation of a strand were coupled with averaging of the synaptic noise in order to look for small events temporally related to the stimuli. Short latency small depolarizations, looking-like recurrent EPSPs, were revealed in 22/142 and 5/15 PMs respectively. 5. These results confirm the existence of interrelations between PMs, providing for re-excitation and coupling within the phrenic pool, in addition to centrally imposed synchronization.
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 74 (1989), S. 272-278 
    ISSN: 1432-1106
    Keywords: Cat ; Corpus callosum ; Optic chiasm ; Stereoacuity ; Visual acuity ; Visual fields
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We studied the role of the transcallosal pathway in stereopsis by measuring binocular and monocular depth perception in two cats that had undergone section of the optic chiasm at the age of 21 d. To ensure that the surgery did not impair vision to the extent that depth perception could not be evaluated, visual acuity and visual fields were also measured. In both of the chiasm-sectioned animals the visual fields were reduced and the visual acuity was substantially lower than in normal cats, with a maximum of about 2 cyc deg-1. Binocular depth thresholds of the chiasm-sectioned cats were worse than those of the normal cat but were better than their own monocular thresholds. These results suggest that the chiasm-sectioned animals were still able to use binocular cues to judge depth and indicate that the indirect pathway through the corpus callosum is sufficient to mediate binocular depth perception.
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  • 18
    ISSN: 1432-1106
    Keywords: Precerebellar nuclei ; Cerebellar cortex and nuclei ; Fluoro-Gold ; Rhodamine-B-isothiocyanate (RITC) ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The projections from certain brain stem precerebellar nuclei to the cerebellar cortex and nuclei have been examined in the cat by using the retrograde fluorescent double-labelling technique. Crystalline Fluoro-Gold was implanted into the left cerebellar nuclei from the contralateral side and rhodamine-B-isothiocyanate was injected into the overlying cerebellar cortex. The inferior olive, the lateral reticular nucleus, and the reticular tegmental pontine nucleus all contained double- as well as single-labelled neurons, and it was concluded that these nuclei have a high number of neurons whose axons branch to both the cerebellar cortex and nuclei. The neurons in the paramedian reticular nucleus and the pontine nuclei proper appear to project only to the cerebellar cortex.
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  • 19
    ISSN: 1432-1106
    Keywords: Cutaneous EPSPs ; Fictive locomotion ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We examined modulation of transmission in short-latency, distal hindlimb cutaneous reflex pathways during fictive locomotion in 19 decerebrate cats. Fictive stepping was produced either by electrical stimulation of the mesencephalic locomotor region (MLR) or by administration of Nialamide and 1-DOPA to acutely spinalized animals. Postsynaptic potentials (PSPs) produced by electrical stimulation of low threshold afferents (〈 2.5 times threshold) in the superficial peroneal (SP), sural, saphenous or medial plantar nerves were recorded intracellularly from various extensor (n = 28) and flexor (n = 24) motoneurons and averaged throughout the step cycle, together with voltage responses to intrasomatic constant current pulses (in order to monitor relative cell input resistance). Each motoneuron studied displayed rhythmic background oscillations in membrane potential and correlated variations in input resistance. The average input resistance of extensor motoneurons was lowest during mid-flexion, when the cells were relatively hyperpolarized and silent. Conversely, average input resistance of flexor motoneurons was highest during mid-flexion, when they were depolarized and active. The amplitude of the minimum-latency excitatory components of PSPs produced by cutaneous nerve stimulation were measured from computer averaged records representing six subdivisions of the fictive step cycle. Oligosynaptic EPSP components were consistently modulated only in the superficial peroneal responses in flexor motoneurons, which exhibited enhanced amplitude during the flexion phase. With the other skin nerves tested (sural, saphenous, and plantar), no consistent patterns of modulation were observed during fictive locomotion. We conclude that transmission through some, but not all, oligosynaptic excitatory cutaneous pathways is enhanced by premotoneuronal mechanisms during the flexion phase of fictive stepping in several cat hindlimb motor nuclei. The present results suggest that the patterns of interaction between the locomotor central pattern generator and excitatory cutaneous reflex pathways depend on the source of afferent input and on the identity of the target motoneuron population.
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 78 (1989), S. 336-344 
    ISSN: 1432-1106
    Keywords: Vagal pharyngeal nerve ; Glossopharyngeal nerve ; Single fibre recordings ; Respiratory-related units ; Superior laryngeal nerve ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In decerebrate, paralyzed and artificially ventilated cats, we recorded the discharge of 64 motor axons supplying the pharyngeal muscles. Filaments containing motor axons, with discharges related to the respiratory cycle (phrenic nerve activity), were teased from the pharyngeal branches of the vagus and glossopharyngeal nerves. Most units (n = 41) fired only during expiration and exhibited a steady, a decreasing or a late augmenting discharge pattern. These units were found only in vagal filaments. Twenty three units discharged during inspiration and exhibited a steady, a late augmenting or a tonic discharge pattern. The inspiratory-related units were present in both the vagus (n=13) and glossopharyngeal (n=10) nerves. Nineteen of 20 pharyngeal inspiratoryrelated units tested were activated at short latency (range 3.4 to 8.0 ms) by stimulation of afferents in the superior laryngeal nerve (SLN). In 13 of these, such stimulation also suppressed their spontaneous activity. SLN stimulation elicited in all 17 pharyngeal expiratory-related units tested a short latency (range 0 to 8 ms) reduction of activity, followed in 7 units by an increase in activity. SLN stimulation occasionally evoked single or rhythmic multifibre bursts in the vagal pharyngeal filaments. These bursts, involving expiratory-related units, likely correspond to the buccopharyngeal stage of swallowing.
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  • 21
    ISSN: 1432-1106
    Keywords: Bicuculline ; Inhibition ; Latency ; Receptive field profile ; Somatosensory cortex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In cortical area 3b of cats, responses of 76 single neurons to punctate indentations were recorded before and during iontophoretic administration of bicuculline methiodide (BMI), a GABAergic antagonist, at levels that did not affect spontaneous activity. Constant amplitude indentations were applied to selected sites along distalproximal and radial-ulnar axes that intersected the most sensitive area in the receptive field. Profiles of response magnitudes were used to measure receptive field dimensions before and during antagonism of GABAergic inhibition. Blockade of GABAergic transmission caused receptive field dimensions of 48 rapidly-adapting neurons to increase an average 141%, or nearly 2.5 times their original size. Analysis of the spatial distribution of inhibition indicated that in-field inhibition was larger than surround inhibition. During BMI administration, response latency was significantly longer for response elicited from the expanded territory than for responses elicited from within the original receptive field, suggesting that receptive field expansion might be mediated by multisynaptic intracortical connections. The magnitude of receptive field expansion was independent of receptive field size or peripheral location. In a substantial number of neurons, however, BMI produced asymmetric expansions that extended only in the proximal direction. For 9 slowly-adapting neurons, BMI produced measureable increases in receptive field dimensions, but these changes were significantly smaller than the changes in rapidly-adapting neurons.
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  • 22
    ISSN: 1432-1106
    Keywords: NMDA receptor ; Visual cortex ; Excitatory amino acid ; Slice ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Actions of excitatory amino acid (EAA) antagonists on the responses of cells in layers II/III and IV of the cat's visual cortex to stimulation of layer VI and the underlying white matter were studied in slice preparations. Antagonists used were 2-amino-5-phosphonovalerate (APV), a selective antagonist for the N-methyl-D-aspartate (NMDA) type of EAA receptors, and kynurenate, a broadspectrum antagonist for the three types of EAA receptors. In extracellular recordings it was demonstrated that most of the layer II/III cells were sensitive to APV, while the great majority of the layer IV cells were not, By contrast, kynurenate suppressed the responses completely in both layers. Excitatory post-synaptic potentials (EPSPs) evoked by stimulation of layer VI and the while matter were recorded intracellularly from layer II/III neurons. To determine whether the EPSPs were elicited mono- or polysynaptically, the synaptic delay for each EPSP was calculated from a pair of onset latencies of EPSPs evoked by stimulation of the two sites. Forty-two percent of the layer II/III cells were classified as having monosynaptic EPSPs. In 60% of these monosynaptic cells, the rising slope of the EPSPs was reduced by APV while in the other 40%, it was not. In the former (APV-sensitive cells), subtraction of the APV-sensitive component from the total EPSP indicated that the onset latency of the NMDA receptor-mediated component was roughly equal to that of the non-NMDA component. In the latter (APV-resistant cells), only the slowly-decaying component was in part mediated by NMDA receptors. The conduction velocities of the afferent fibers innervating APV-resistant cells were slower than those of the APV-sensitive cells, suggesting that both types of cells are innervated by different types of afferents. The polysynaptic EPSPs of almost all layer II/III cells were sensitive to APV. The subtraction method indicated that the NMDA component had about the same magnitude as the non-NMDA components. When the slices were superfused by a Mg2+-free solution, the EPSPs were potentiated dramatically, but this potentiation was reduced to the control level during the administration of APV. Similarly, APV-sensitive components were potentiated during the administration of bicuculline, a selective antagonist for gamma-aminobutyric acid receptors of A type. These results suggest that NMDA receptors participate, at varying degrees, in excitatory synaptic transmission at most layer II/III cells in the cat's visual cortex, and their actions appear to be regulated by intracortical inhibition.
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  • 23
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    Experimental brain research 78 (1989), S. 374-379 
    ISSN: 1432-1106
    Keywords: Thermosensitivity ; Spinal cord ; Ascending pathways ; Behaviour ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The behavioural thermosensitivity of six cats was measured before and after single stage, symmetrical, bilateral, surgical lesions of the cervical spinal cord. The lesions were aimed at an area in the most ventral parts of the dorsal halves of the lateral funiculi. Unilateral lesions of that area have previously been found to cause reproducible, although subtotal, contralateral thermosensory defects, which were attributed to interruption of the thermosensory spinothalamic pathway. The lesions of three of the present cats were found to be incomplete, and those animals showed no postoperative thermosensory deficiency. Two of the cats with complete lesions showed marked post-operative defects, especially immediately after the operations, but the third cat with a complete lesion showed no postoperative thermosensory defect at all. The differences between the last three animals have been compared to the irregularity of previous reports about thermosensitivity after spinal cord lesions in man and animals, and may depend on the testing technique, rather than differences of thermosensitivity per se.
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  • 24
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    Experimental brain research 78 (1989), S. 501-513 
    ISSN: 1432-1106
    Keywords: Somatosensory cortex ; Interlaminar ; Corticortical ; SI ; Area 3b ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The morphology of single neurons in area 3b of cat primary somatosensory (SI) cortex was examined after horseradish peroxidase (HRP) injections. Neurons were labeled either by intracellular injection of HRP following intracellular recording or by small extracellular iontophoretic HRP injections. Both pyramidal and nonpyramidal neurons were labeled and reconstructed from serial sections. Their axons had local, interlaminar and interareal patterns of termination. Most neurons formed local axonal fields around their cell bodies and dendrites. Pyramidal neurons in cortical layer IV sent axons up into layers II and III, neurons in layers II and III sent axons down to layer V, and layer V neurons sent axons to layer VI as well as back to the upper layers. Layer VI neurons sent axons back to the upper cortical layers in a unique bowl-shaped pattern. The horizontal distribution of axons of pyramidal cells in layer III was extremely widespread. Axons of layer III neurons in area 3b terminated within 3b and area 1, but not in other areas of SI. Layer III neurons in area 1 distributed axon collaterals to all fields of SI as well as projecting a main axon to motor cortex. In general, the axon collaterals of area 3b pyramidal cells outside layer III remained confined to area 3b. Most of the nonpyramidal neurons labeled were basket cells in layers III and VI. These neurons formed dense axonal fields around their cell bodies, and none of their axons could be followed into the underlying white matter. The results of the present study demonstrate that area 3b somatosensory cortical neurons and their axons are vertically organized in a manner similar to that reported for other sensory cortical areas. They also show that widespread horizontal connections are formed by pyramidal neurons of layer III, and that these horizontal axons can travel for great distances in the cortical grey matter.
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  • 25
    ISSN: 1432-1106
    Keywords: Motor cortex ; Conditioned movement ; Posture ; Balance control ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The role of the sensorimotor cortex in the postural adjustments associated with conditioned paw lifting movements was investigated in the cat. Cats were trained to stand quietly on four strain gauge equipped platforms and to perform a lift-off movement with one forelimb when a conditioned tone was presented. The parameters recorded were the vertical forces exerted by the paws on each platform, the lateral and antero-posterior displacements of rods implanted on the T2, T12, L5 vertebrae as well as their rotation, and the EMG of triceps and biceps of both forelimbs. Before lesion, the postural adjustment consisted of a “nondiagonal” pattern where the CG was displaced laterally inside the triangle formed by the three remaining supporting limbs. Here a lateral bending of the thoracic column toward the supporting forelimb could be observed. The associated EMG pattern consisted of an early activation of the triceps lateral head in the moving limb which was probably responsible for the body displacement toward the opposite side, and a late biceps activation associated with the lift. In the supporting forelimb, a coactivation of the biceps and triceps was usually present. After contralateral sensorimotor lesion, the conditioned lifting movements were lost for 4–15 days after the lesion, before being subsequently recovered. The same lateral CG displacement and bending of the back was seen after lesion as before, which indicates that the goal of postural adjustment was preserved. However, the means of reaching it were modified. In most of the intact animals, the CG displacement was achieved in one step, whereas in the animals with lesions, the displacement was made either according to a slow ramp mode or in a discontinuous manner involving several steps. The mechanisms responsible for this disturbance are discussed.
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  • 26
    ISSN: 1432-1106
    Keywords: Somatosensory cortex ; Directional sensitivity ; GABA inhibition ; Picrotoxin ; Bicuculline ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The role of intracortical inhibitory processes in the formation of neuronal receptive fields in the vibrissal projection zone of the somatosensory cortex was studied. Iontophoretic application of picrotoxin and bicuculline blocks the inhibition and causes the loss of directional sensitivity in neurons. Activation of inhibition by distant glutamate application gives opposite results — neurons become direction sensitive. A dependence was found between spatial location of activated cells and the pattern of changes of their detector properties. Inhibitory processes caused by natural afferent stimulation lead to similar changes in the functional properties of neurons.
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  • 27
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    Experimental brain research 78 (1989), S. 203-213 
    ISSN: 1432-1106
    Keywords: Corpus callosum ; Development ; Vision ; Dark rearing ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary It is now well established that during normal postnatal development there is a partial elimination of the callosal projections of cortical areas 17 and 18 in the cat and that visual experience early in life can modulate this process. In the present experiments, we quantitatively studied the influence of light, per se, by rearing cats in total darkness. Dark rearing exaggerates the normally occurring partial elimination of immature callosal projections: it causes a significant reduction in the total number of neurons in both the supra-and infragranular layers that send an axon through the corpus callosum and slightly narrows the distribution of these neurons across areas 17 and 18. These data demonstrate that visual stimulation is not necessary either to initiate the partial elimination of immature callosal projections or to stabilize a large fraction of the callosal projections present at birth. However, normal visual stimulation is necessary for the stabilization of the normal complement of callosal projections.
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  • 28
    ISSN: 1432-1106
    Keywords: Control of respiration ; Intercostal muscle afferents ; Phrenic nerve ; Abdominal muscle afferents ; Expiratory neurons ; Abdominal muscle control ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Our objective was to determine if caudal ventral respiratory group (VRG) expiratory (E) neurons that drive abdominal expiratory motoneurons in the lumbar cord respond to intercostal and lumbar nerve afferent stimulation. Results showed that 92% of medullary E-neurons that were antidromically activated from the upper lumbar cord reduced their activity in response to stimulation of external and internal intercostal and lumbar nerve afferents. We conclude that afferent information from intercostal and abdominal muscle tendon organs has an inhibitory effect on caudal VRG E-neurons that drive abdominal expiratory motoneurons.
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  • 29
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    Pflügers Archiv 414 (1989), S. 235-244 
    ISSN: 1432-2013
    Keywords: Cat ; Urinary bladder ; Parasympathetic ganglion neurone ; Postganglionic stimulation ; Synaptic potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Intracellular recording techniques were used to examine and compare synaptic potentials evoked by stimulating pre- and postganglionic nerve trunks in cat bladder parasympathetic ganglia. In the 76 ganglion cells exammed, two types of responses were recorded on stimulating the postganglionic nerve: an antidromic action potential (type Post NS1;n=30) or a fast excitatory postsynaptic potential (f-EPSP; type PostNS2;n=46) which resulted in an orthodromic-like action potential. In some of the cells exhibiting a PostNS1 response (n=19), a fast depolarization was superimposed on the antidromic spike. This depolarization was due to the synaptic activation of nicotinic receptors. In many of the cells exhibiting either PostNS1 or PostNS2 responses, repetitive stimulation of the postganglionic nerve induced a slow hyperpolarization. Applying nicotinic (hexamethonium, methonium, 0.5–1 mM), muscarinic (atropine, 1 μM), alpha-adrenergic (phentolamine, 1 μM) and purinergic (caffeine, 0.5–1 mM) receptor antagonists completely inhibited the tetanus-induced slow hyperpolarization in some cells (n=5). In other cells (n=15), a slow hyperpolarization persisted in the presence of these antagonists. These results indicate that stimulation of the postganglionic nerve trunk of cat bladder parasympathetic ganglia can elicit not only an antidromic action potential, but also synaptic potentials which are mediated by the activation of cholinergic (nicotinic and muscarinic), noradrenergic and purinergic receptors, as well as a non-cholinergic, non-alpha-adrenergic and non-purinergic synaptic potential.
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  • 30
    ISSN: 1432-2072
    Keywords: Oro-facial dyskinesia ; Globus pallidus ; GABA ; Acetylcholine ; Behaviour ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The possible role of cholinergic mechanisms in the sub-commissural part of the globus pallidus (scGP) in the induction of oro-facial dyskinesia (OFD) was studied in cats. Local injections of the cholinergic agonist carbachol into the scGP elicited tongue protrusions in a dose dependent way (100–1000 ng/0.5 μl). The effect elicited by 1000 ng carbachol was selectively antagonized by the cholinergic antagonist scopolamine (10 μg/0.5 μl); this dose of scopolamine was ineffective when injected alone. The tongue protrusions resulted from both normal and abnormal movements: whereas normal movements simply consisted of protruding the flat tongue, abnormal movements implied a variety of movements, especially curling upwards the lateral side(s) or tip of the tongue inside or outside the oral cavity. The abnormal carbachol-induced tongue protrusions formed part of a syndrome marked by dyskinetic movements of the muscles of the eye, ear and cheek, and were identical to those seen previously after local injections of picrotoxin (250–500 ng). Intra-pallidal injections of the abovementioned dose of scopolamine had no effect on the tongue protrusions induced by local injections of 375 ng picrotoxin. However, local injections of 100 ng muscimol, which was previously found to attenuate significantly the effect of 375 ng picrotoxin and which was ineffective when injected alone, significantly attenuated the tongue protrusions induced by local injections of 1000 ng carbachol. These data suggest that the cholinergic effects are mediated via a GABAergic mechanism, but not vice versa. The results are discussed in view of GABAergic and anticholinergic therapies used in oro-facial dyskinesia.
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  • 31
    ISSN: 1432-1912
    Keywords: 5-HT3 receptors ; Radioligand binding ; [3H]ICS 205-930 ; Cat ; Rabbit ; Vagus nerve ; Superior cervical ganglion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The binding characteristics of [3H]ICS 205-930, a 5-hydroxytryptamine 5-HT3 receptor antagonist, were investigated in membranes prepared from cat and rabbit vagus nerve (VN) and superior cervical ganglion (SCG). The autoradiographic localisation of 5-HT3 recognition sites was also assessed using [3H]ICS 205-930 in slices from cat medulla oblongata, nodose ganglion and vagus nerve. [3H]ICS 205-930 bound to a homogeneous population of high affinity recognition sites in cat VN: Bmax = 201 ± 43 fmol/mg protein, pKD = 9.26 ± 0.17 and SCG: Bmax = 291 ± 40 fmol/mg, pKD = 9.35 ± 0.80 (n = 3). Competition experiments performed in membranes from cat VN and SCG with agonists and antagonists suggested the presence of a homogeneous population of [3H]ICS 205-930 recognition sites. Competition curves were steep and monophasic and were best fitted by a 1 receptor site model. The following rank order of affinity for [3H]ICS 205-930 binding sites was observed with antagonists: SDZ 206-830 = ICS 205-930 〉 BRL 43694 〉 SDZ 206–792 〉 quipazine 〉 MDL 72222 〉 metoclopramide 〉 mCPP and agonists: 2-methyl-5-HT = 5-HT 〉 phenylbiguanide. A similar profile was observed for a limited series of compounds in rabbit membranes. Drugs acting at 5-HT1, 5-HT2 and dopamine receptors (domperidone, spiperone and metergoline) showed very low affinities for [3H]ICS 205-930 recognition sites. The sites labelled with [3H]ICS 205-930 in vagus nerve and superior cervical ganglion of both species displayed the pharmacological profile of a 5-HT3 receptor. There was a significant correlation between the rank order of affinity of the tested compounds for [3H]ICS 205-930 recognition sites in cat and rabbit membranes and their rank order of affinity for 5-HT3 receptors from neuroblastoma-glioma NG 108-15 cells. Autoradiographic studies suggest that [3H]ICS 205-930 binding sites are present over and around the nodose ganglion cell somata, along certain fibers of the vagus nerve and in the terminal areas of this nerve in the medullar nucleus of the vagus. The present data demonstrate that [3H]ICS 205-930 identifies 5-HT3 receptors in preparations of cat and rabbit vagus nerve and superior cervical ganglion.
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  • 32
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    Naunyn-Schmiedeberg's archives of pharmacology 340 (1989), S. 764-766 
    ISSN: 1432-1912
    Keywords: Nucleus of the solitary tract (NTS) ; GABA release ; Carotid occlusion ; Blood pressure ; Push-pull cannula ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In anaesthetized cats, the nucleus of the solitary tract was bilaterally superfused through push-pull cannulae with artificial cerebrospinal fluid (CSF) and the effect of carotid occlusion on the release of endogenous GABA was investigated. Bilateral carotid occlusion led to a rise in blood pressure which was associated with a very pronounced increase in the release rate of GABA in the nucleus of the solitary tract. The results demonstrate the hypertensive function of GABA in the nucleus of the solitary tract and the importance of GABAergic neurons of this nucleus for the central cardiovascular control.
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  • 33
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    Cell & tissue research 258 (1989), S. 611-616 
    ISSN: 1432-0878
    Keywords: Cell communication ; Dye-coupling ; Odontoblasts ; Gap junctions ; Dentin sensitivity ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cell communication between odontoblasts was investigated with the use of fluorescent-dye tracers; Lucifer Yellow CH (molecular weight = 457.3), and dextran-Lucifer Yellow CH (average molecular weight = 10000). Dyes were injected into cell bodies of individual odontoblasts via an intracellular microelectrode or into a group of cells through their processes, and passage to adjacent cells was examined with a fluorescence microscope. Lucifer Yellow CH appeared to diffuse very easily among odontoblasts, while dextran-Lucifer Yellow remained within the injected cell or cells. This efficient migration of Lucifer Yellow CH can be considered a functional manifestation of gap junctions between odontoblasts.
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  • 34
    ISSN: 1432-0878
    Keywords: Autonomic ganglia ; Spinal ganglia ; Sensory neurons ; Neurotransmitters ; Sweat glands ; Blood vessels ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The neuronal subpopulations in the cat stellate, lower lumbar and sacral sympathetic ganglia were studied with regard to the cellular distribution of immunoreactivity to tyrosine hydroxylase (TH), acetylcholinesterase (AChE) and various neuronal peptides. Coexistence of neuropeptide Y (NPY)- and galanin (GAL)-like immunoreactivity (LI) was found in a high proportion of the neuronal cell bodies; these cells also contained immunoreactivity to TH, confirming their presumably noradrenergic nature. Some TH- and GAL-immunoreactive principal ganglion cells lacked NPY-LI. Two populations (scattered and clustered) of vasoactive intestinal polypeptide (VIP)- and peptide histidine isoleucine (PHI)-positive cell bodies were found in the sympathetic ganglia studied. The scattered VIP/PHI neurons also contained AChE-LI, calcitonin gene-related peptide (CGRP)-and, following culture, substance P (SP)-LI. The clustered type only contained AChE-LI. In the submandibular and sphenopalatine ganglia, neurons were AChE- and VIP/ PHI-immunoreactive but lacked CGRP- and SP-LI. Many GAL- and occasional TH-positive neurons were found in these ganglia. In the spinal ganglia, single NPY-immunoreactive sensory neuronal cells were observed, in addition to CGRP- and SP-positive neurons. The present results show that there are at least two populations of sympathetic cholinergic neurons in the cat. Retrograde tracing experiments indicate that the scattered type of cholinergic neurons contains four vasodilator peptides (VIP, PHI, CGRP, SP) and provides an important input to sweat glands, whereas the clustered type (containing VIP and PHI) mainly innervates blood vessels in muscles.
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  • 35
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    Cell & tissue research 257 (1989), S. 549-554 
    ISSN: 1432-0878
    Keywords: Salivary secretion ; Parotid gland ; Exocytosis ; Secretory granules ; Autonomic nerve-stimulation ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron microscopy of cat parotid glands revealed great heterogeneity in the secretory granules of normal unstimulated acinar cells. Electrical stimulation of the parasympathetic nerve to the gland evoked a copious flow of parotid saliva which was accompanied by an extensive depletion of the secretory granules from the acinar cells. Exocytosis was captured as it was occurring by means of perfusion-fixation, and showed that the events occur in a conventional manner. Stimulation of the sympathetic nerve caused only a very small flow of saliva, and no acinar degranulation was detected. It can be concluded that the parasympathetic secretomotor axons provide the main drive for parotid acinar degranulation in the cat. This contrasts with the rat in which sympathetic impulses provide the main stimulus for parotid acinar degranulation. These dissimilarities serve to emphasise how extensively species differences may influence autonomic responses in salivary glands.
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  • 36
    ISSN: 1573-9686
    Keywords: Electrical stimulation ; Neural damage ; Peripheral nerve electrode ; Peroneal nerve ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Helical electrodes were implanted around the left and right common peroneal nerves of cats. Three weeks after implantation one nerve was stimulated for 4–16 hours using charge-balanced, biphasic, constant current pulses. Compound action potentials (CAP) evoked by the stimulus were recorded from over the cauda equina before, during and after the stimulation. Light and electron microscopy evaluations were conducted at various times following the stimulation. The mere presence of the electrode invariably resulted in thickened epineurium and in some cases increased peripheral endoneurial connective tissue beneath the electrodes. Physiologic changes during stimulation included elevation of the electrical threshold of the large axons in the nerve. This was reversed within one week after stimulation at a frequency of 20 Hz, but often was not reversed following stimulation at 50–100 Hz. Continuous stimulation at 50 Hz for 8–16 hours at 400 μA or more resulted in neural damage characterized by endoneurial edema beginning within 48 hours after stimulation, and early axonal degeneration (EAD) of the large myelinated fibers, beginning by 1 week after stimulation. Neural damage due to electrical stimulation was decreased or abolished by reduction of the duration of stimulation, by stimulating at 20 Hz (vs. 50 Hz) or by use of an intermittent duty cycle. These results demonstrate that axons in peripheral nerves can be irreversely damaged by 8–16 hours of continuous stimulation at 50 Hz. However, the extent to which these axons may subsequently regenerate is uncertain. Therefore, protocols for functional electrical stimulation in human patients probably should be evaluated individually in animal studies.
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  • 37
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    Acta neuropathologica 69 (1986), S. 17-22 
    ISSN: 1432-0533
    Keywords: Brain abscess ; Cat ; Energy state ; Substrate mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Brain abscesses were induced experimentally in six cats by stereotactic inoculation ofStaphylococcus aureus A8 into the white matter of the left cerebral hemisphere. Seven days later, the brains were frozen in situ with liquid nitrogen and subsequently sawn into coronal sections of 5 mm thickness, while being cooled with liquid nitrogen. Thin slices were taken from those sections containing the largest expanse of abscess: slices of 5 μm thickness were stained histologically, and in adjacent 20 μm slices the regional distribution of ATP and glucose was mapped using substrate-specific bioluminescence methods. Furthermore, the NADH fluorescence from the surface of the tissue section was recorded. Six layers could be distinguished histologically in the abscess capsule, five of which showed different substrate patterns. Only in two layers a low metabolic activity could be observed, as shown by slight ATP bioluminescence. The pattern of the biochemical substrates in the white matter surrounding the abscess indicated a reduction in the cellular oxygen availability.
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  • 38
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    Anatomy and embryology 173 (1986), S. 323-342 
    ISSN: 1432-0568
    Keywords: Cerebral cortex ; Corpus callosum ; Anterior commissure ; Columns ; Horseradish peroxidase ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This investigation had four goals: First, to study the general topography of the corpus callosum (CC) of the cat. Second, to study the columnar organization of CC terminals and map their banding pattern in the cortex. Third, to examine the relation between CC neuron density and the presence of CC terminal columns. Fourth, to determine whether CC and anterior commissure (AC) neuron distributions are intermixed. Eight adult cats were subjected to partial commissurotomies, and then to large injections of horseradish peroxidase to one cerebral hemisphere. Processing with tetramethyl benzidine revealed retrogradely labelled cells and anterogradely labelled terminals in the cortex of the uninjected hemisphere. The distributions of these cells and terminals were examined by light microscopy and analyzed by computer microscopic methods. The genu of the CC interconnects frontal portions of the cortex, the body interconnects mostly dorsal portions of the cortex, while the splenium interconnects the temporal and occipital cortices. Reconstructions of the CC terminal columns reveal intricate banding patterns in several non-primary areas of the cortex. CC cell density is greater within than outside the terminal columns. CC and AC neurons intermix in the infragranular lavers of the neocortex.
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  • 39
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    Anatomy and embryology 173 (1986), S. 371-376 
    ISSN: 1432-0568
    Keywords: Motilin-like immunoreactivity ; RIA ; HPLC ; Cat ; Intestine ; Rat ; Cerebellum ; Purkinje cells ; Dendrites ; Neocortex ; Pyramidal cells ; Hippocampus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Motilin was demonstrated by the immunoperoxidase technique in endocrine cells of the gastrointestinal tract using several specific antisera. Motilin-like immunoreactivity could only be demonstrated with one of these antisera and was observed in Purkinje cells and dendrites of the cerebellum, in pyramidal cells and dendrites of the cerebral cortex and in dendrites of the CA3 field of the hippocampus of the rat. Very low motilin-like immunoreactivity was found in cerebellum as well as in cerebral cortex using radioimmunoassay. However, using reverse phase liquid chromatography combined with UV-detection and radioimmunoassay, no peak of a peptide corresponding to synthetic motilin was detectable in rat cerebellar extracts, in contrast to findings in rat duodenum. The results do not suggest that motilin is an intrinsic neuroactive substance of the cerebellum.
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  • 40
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    Anatomy and embryology 175 (1986), S. 261-269 
    ISSN: 1432-0568
    Keywords: Lateral reticular nucleus ; Edinger-Westphal nucleus ; Retrograde transport of WGA-HRP ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary By means of retrograde axonal transport of the wheat germ agglutinin — horseradish peroxidase complex, a projection from the Edinger-Westphal nucleus to the lateral reticular nucleus was demonstrated in the cat. Following small tracer ejections in the main part of the lateral reticular nucleus, a significant number of labelled neurons were found bilaterally throughout the Edinger-Westphal nucleus. Most of the labelled cells were located on the ipsilateral side. The projecting neurons are spindle-shaped to round with a maximum diameter of the cell body between 15 and 30 μm. The findings are discussed in relation to other Edinger-Westphal efferent projections, and some comments are made concerning the cytoarchitecture and delineation of the feline Edinger-Westphal nucleus.
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  • 41
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    Experimental brain research 62 (1986), S. 479-485 
    ISSN: 1432-1106
    Keywords: Cat ; Double labelling ; Fluorescent tracing ; Lateral cervical nucleus ; Ascending and descending neurones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The organization of ascending and descending neurones of the lateral cervical nucleus (LCN) was investigated in 10 adult cats after injections of the fluorescent tracers Fast Blue and Nuclear Yellow. Injections into the thalamus and tectum resulted in up to 3000 labelled cell profiles within the contralateral LCN. This corresponded to a calculated number of 4500 labelled LCN neurones. The greatest diameter of the labelled cell profiles was about 30 μm. They were located throughout the nucleus, but were less numerous in its medial portion. Injections mainly into the dorsal horn of different pairs of cervical and lumbar segments of the spinal cord resulted in a calculated number of up to 305 labelled LCN cells. The diameter of these cell profiles was about 25 μm and they were mainly situated in the rostro-ventral and medial parts of the LCN. Doublelabelled cells with ascending and descending projections were not encountered after injections into the thalamus-tectum and spinal segments C5-6. About 15% of the descending LCN cells were doublelabelled by pairs of spinal injections separated by intervals of one segment. It is concluded that the neurones descending down the spinal cord and ascending to the thalamus-tectum constitute different subpopulations of cells within the LCN and that a minor proportion of the descending cells seem to project to at least three adjacent segments of the spinal cord.
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  • 42
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    Experimental brain research 61 (1986), S. 280-290 
    ISSN: 1432-1106
    Keywords: Cerebral cortex ; Phrenic nerve ; Phrenic motoneurones ; Medullary pyramids ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Short latency responses were recorded from C5 phrenic roots and intracellularly from phrenic motoneurones following stimulation of the pericruciate cortex or medullary pyramids in cats anaesthetized with Nembutal or chloralose-urethane. Focal stimulation of the cortical surface (single pulses, 0.5–2 ms, 0.3–8 mA) during inspiration evoked EPSPs (latency 4.7 ± 1.7 ms, rise time 1.9 ± 1.1 ms, amplitude 0.22 to 3.94 mV) in 42% of motoneurones studied (n = 107). The EPSPs were absent, or on average 60% smaller, following stimulation during expiration. In all but two motoneurones, during both inspiration and expiration, hyperpolarizing potentials were observed either following the initial depolarization or alone. They could be reversed by hyperpolarizing current or chloride injection. Stimulation of the pyramidal tract at mid medullary level (1 to 3 pulses, 0.2 ms) evoked short latency excitation in phrenic motoneurones only with currents of more than 200 μA. Smaller stimuli applied to the medial reticular formation above the pyramidal tract evoked excitation (onset latency 1.5–3.2 ms) in which the earliest part was probably monosynaptic. These results show that the corticospinal responses in phrenic motoneurones are both excitatory and inhibitory. They are not transmitted through the pyramidal tract and are at least disynaptic. Excitation evoked from the medullary pyramidal tract can be explained by current spread beyond the pyramidal tract fibres.
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  • 43
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    Experimental brain research 63 (1986), S. 443-448 
    ISSN: 1432-1106
    Keywords: Visual cortex (area 17) ; Intrinsic connections ; Visual deprivation ; Development ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Intracortical injections of horseradish peroxidase conjugated with wheat-germ agglutinin (WGA-HRP) reveal a characteristic patchy staining pattern within the superficial layers of cat striate cortex. The patches consist of a dense accumulation of labeled neurons and axonal arborizations. We have investigated the tangential organization and the development of these intrinsic cortical connections by using a flat-mount preparation of area 17. The diameter of the patches varied from 200 to 400 μm, the center-to-center distance ranged from 400 to 800 μm, and the spread of patches extended further in the anterior-posterior than in the medial-lateral direction. The expression of these horizontal patchy connections is age- and experience-dependent. From ten days to six weeks of age patches are exuberant and on occasion fuse to beaded bands extending radially from the injection site. From 6 weeks onwards the number and the tangential spread of the patches decreases to one or two rows of isolated clusters. Long-term binocular deprivation disrupts this pattern of intrinsic connections nearly completely. We infer from these results that there is an inborn pattern of discrete horizontal connections in striate cortex which is shaped by visual experience and requires contour vision for its maintenance.
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  • 44
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    Experimental brain research 62 (1986), S. 273-280 
    ISSN: 1432-1106
    Keywords: Motoneurons ; Interactions ; Cholinergic synapses ; Phrenic nerve ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Interactions between phrenic motoneurons have been analysed in anaesthetized, paralyzed cats after C3 to C7 deafferentation. Effects of electrical stimulation of the C5 phrenic axons have been studied on thin filaments dissected from the stimulated nerve. Repetitive stimulation could elicit, after the primary direct response of the stimulated axons, a secondary response named Recurrent Response, RR. 2. RRs have been obtained in 117/186 phrenic axons. They appear sporadically (mean occurrence: 3.75 RRs elicited by 100 shocks of stimulation) at a constant latency. They originate from a spinal mechanism since they persist after C2 transection and disappear after section of the ventral roots. 3. The mechanism responsible for RR shows spatial and temporal facilitation. The RR probability increases with the number of antidromically invaded motoneurons as revealed by changes either of stimulation intensity or of central respiratory drive. However, RR could be evoked in a motoneuron without an antidromic volley in its axon. 4. Systemic injections of nicotinic blocking drugs such as dihydro-β-erytroidin or mecamylamine decrease or suppress the occurrence of RR; therefore, cholinergic synapses are involved in the RR generating process. 5. RR are assumed to be due to direct excitatory interactions between homonymous motoneurons. Recurrent axon collaterals impinging directly on neighbouring motoneurons would link together the different motoneurons of the phrenic pool. The functional significance of this phenomenon is discussed.
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  • 45
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    Experimental brain research 62 (1986), S. 281-292 
    ISSN: 1432-1106
    Keywords: PT cell ; Areas 4γ and 5 ; Intracortical microstimulation ; HRP ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The cortico-cortical projection from area 5 to area 4 γ was studied in anesthetized cats. 2. Intracortical microstimulation of area 5 produced EPSPs in pyramidal tract (PT) cells in area 4 γ. Such EPSPs were analysed in a total of 54 fast PT cells. The rising phase of these EPSPs was often composed of fast and slow components. 3. Fast-rising EPSPs (fast component) were produced predominantly by stimulation within layer III of area 5 while slow-rising EPSPs (slow component) were evoked predominantly by stimulation within layer V of area 5. 4. The amplitudes of the fast and slow components of EPSPs produced during repetitive stimulation within layers III and V of area 5 decreased and increased, respectively, with an increase in the stimulus frequency without any appreciable changes in their latency and time-to-peak. The slow component was much less influenced by membrane hyperpolarization than the fast component. 5. Retrogradely labeled neurons were found not only in layer III but also in layer V of area 5 following HRP injection centered on superficial layers (I–III) of area 4γ. 6. It is suggested that there are two groups of cortico-cortical neurons in layers III and V of area 5, which may make monosynaptic contact with the proximal and distal sites of fast PT cells in area 4γ, respectively.
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  • 46
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    Experimental brain research 61 (1986), S. 585-596 
    ISSN: 1432-1106
    Keywords: Cat ; Chloralose ; Motor cortex ; PT collaterals ; Macro- and microstimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Stimulating electrodes were placed in the red nucleus, lateral hypothalamus and medial thalamus in order to determine whether pyramidal tract (PT) neurons send collaterals to those sites. The red nucleus projections are well-known, but it was discovered that PT neurons also project into the other two sites. All of the fibers that sent collaterals to all three sites originated from fast PT neurons. Those that responded to stimulation of the skin and that sent collaterals to two or three sites were predominantly fast PT neurons. Those neurons that responded only to cerebral peduncle stimulation were predominantly slowly-conducting, when compared with the set of PT neurons in response to cerebral peduncle stimulation. The patterns of collateral branching to red nucleus and to lateral hypothalamus were similar, suggestimg a similar synaptic effect of the pyramidal system in the two sites. Measurement of the speed of conduction from three sites along the length of corticospinal fibers revealed large changes on some, but not all, fibers; there was no evident pattern to these changes that might be associated with collateral branching. A new hypothesis concerning the functional role of fast PT neurons in regulating movement is presented.
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  • 47
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    Experimental brain research 61 (1986), S. 625-637 
    ISSN: 1432-1106
    Keywords: Respiratory neurons ; Cervical spinal cord ; Axonal projection ; Phrenic motoneurons ; Intercostal motoneurons ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study was performed in order to describe the location, axonal projection and possible synaptic action of the inspiratory neurons recently described in the upper cervical cord. In 26 cats anaesthetized with Nembutal, extracellular recordings were made from 224 cervical inspiratory units which were found near the lateral border of lamina VII and formed a column extending from the caudal end of the nucleus retroambigualis at the C1 segment to the rostral half of the C3 segment. Most of the units (approximately 85%) could be excited antidromically from the thoracic cord. Antidromic mapping showed collateral branches to the C5 segment in the vicinity of the phrenic nucleus, occasionally crossing the midline. No synaptic connections with phrenic motoneurones could be revealed either by cross-correlation of the activity of the cervical units with the discharge of C5 phrenic root, or by spike-triggered averaging (STA) of the post-synaptic noise recorded intracellularly from phrenic motoneurons. Extensive branching was found in the examined T3–T5 segments with arborizations near the ipsilateral intercostal motor nuclei and often extending across the midline. Cross-correlation experiments did not show clear monosynaptic connections to the inspiratory intercostal motoneurons. Intracellular recording from intercostal motoneurons and STA resulted in a few (2 out of 37) small, probably disynaptic, e.p.s.p.s. It is concluded that the upper cervical neurons are involved in the control of phrenic and intercostal motoneurons, probably through a disynaptic pathway involving segmental interneurons.
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  • 48
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    Keywords: Antibodies to serotonin ; Immunocytochemistry ; Radioimmunoassay ; Antibodies specificity ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Antibodies to 5-hydroxytryptamine (5-HT) were obtained from 4 rabbits after injections of 5-HT coupled to bovine serum albumin by means of paraformaldehyde (PF). Two methods were used to monitor the developement of antibodies (AB): the one based on the “in vitro” competitive binding properties of the antibodies with3(H)5-HT, the other, on their “in situ” binding properties to endogenous 5-HT, using the peroxidase-anti-peroxidase immunohistochemical technique, applied to paraffin embedded sections of cat brainstem. No pharmacological processing, detergents or proteolytic enzymes were used. The specificity of the antiserum was tested by competitive procedures with 20 analogs using the “in vitro” and “in situ” techniques. “In vitro” studies were performed with 5-HT free analogs and with analogs previously coupled with PF to lysine. Radioimmunological tests showed that the antibodies recognize mainly the ethylamine (CH2-CH2-NH2)-cham of the free analogs and that the best specificity was obtained with the 5-HT conjugate (5-HT-lysine-PF). The results suggest that the hapten is coupled through the phenolic positions C4 or C5. The “in situ” immunohistochemical extinction assays also revealed a distinct specificity for 5-HT. Possible optical and ultrastructural applications are illustrated in the raphé nuclei of the cat. These results confirm the reliability of radioimmunological tests for studying the specificity of AB directed against haptens, provided that haptens and analogs tested were first chemically transformed to resemble the immunogen (herewith lysine-PF coupling) with regard to its antigenic structure.
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  • 49
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    Experimental brain research 62 (1986), S. 486-494 
    ISSN: 1432-1106
    Keywords: Mechanoreceptors ; Thresholds ; Stimulus-response functions ; Cuneatus ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The response characteristics of mechanoreceptive neurons (RA, SA, and PC) innervating the foot pad of cat were determined in the cuneate nucleus. The mechanical stimuli were single sinusoidal pulses of varying frequency (20, 60, 150, and 240 Hz), and vibratory trains of varying frequency (80 and 240 Hz) and duration (50, 100, and 400 ms). Thresholds and stimulus-response functions were determined with single pulses. Absolute thresholds (1 impulse/train), tuning thresholds (1 impulse/cycle), and atonal intervals (the range between absolute and tuning thresholds) were determined with vibratory stimulus trains. When tested with single pulses the thresholds resembled those of primary afferents in all unit populations. The stimulus-response function of PC units but not of all RA units were comparable to those of primary afferents. Noxious conditioning stimulation did not influence the thresholds of cuneate mechanoreceptors in the tested sample (N = 6). Mostly PC units were tested with vibratory trains. Absolute thresholds were not dependent on stimulus duration, which is a consistent finding with peripheral units. In contrast to peripheral units, the tuning thresholds in most PC units were elevated with increasing stimulus duration. The variability in the range of atonal intervals was much larger than in the periphery. Thus, it seems that both the type of the tactile signal and the type of the studied mechanoreceptive neuron are critical parameters in determining whether the response characteristics of neurons in the cuneate and in the periphery are identical or not.
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  • 50
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    Experimental brain research 61 (1986), S. 432-437 
    ISSN: 1432-1106
    Keywords: Claustrum ; Putamen ; Auditory response properties ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The auditory response properties of single neurons in claustrum and putamen were studied in response to simple dichotic stimuli (viz. noise- and tone-bursts) in chloralose-anaesthetized cats. Neurons in claustrum were commonly weakly driven with long latency, were broadly tuned and were excited by stimulation of either ear (EE). Putamen neurons, in contrast, were securely driven with short latency, showed irregular tuning with a preference for low frequencies and were either EE or excited only by the contralateral ear (EO). The differences between claustrum and putamen responses can be related to differences in connections with the auditory cortical fields and with auditory thalamus. Some neurons were also tested for visual responsiveness: auditory and visual cells were intermingled in both nuclei and only a small percentage of cells were bimodal. In contrast to the visual and somatosensory input to claustrum, which are derived from primary cortical fields, the auditory input to claustrum is apparently derived from non-primary cortical regions, suggesting a fundamentally different role for processing of auditory information in claustrum.
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  • 51
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    Experimental brain research 61 (1986), S. 447-450 
    ISSN: 1432-1106
    Keywords: Superior colliculus ; Single units ; Eye movements ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Single unit activity was studied in the intermediate and deep layers of the superior colliculus in two trained cats. Eye movements were recorded with a magnetic search coil, the head being fixed. Discharge rates which varied as a function of eye position were consistently observed in 7 of 67 (about 10%) of the sample of eye movement-related units. These units showed similar changes in firing rate as a function of eye position in total darkness and during task related fixation of visual targets and thus appear to convey an “eye position” signal. Their activity may originate either from proprioception or from corollary discharge.
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  • 52
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    Experimental brain research 63 (1986), S. 581-584 
    ISSN: 1432-1106
    Keywords: Visual neurons ; Contrast ; Binocular interactions ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Dichoptic presentation of patterns similar in shape but of very different contrast results in the perception of only the high contrast pattern (binocular suppression). When recording from binocular neurons of the cat visual cortex, we have found an effect which is strikingly similar to this perceptual phenomenon. If a high and a low contrast grating are presented simultaneously, one to each eye, the cell's response to the low contrast stimulus is suppressed.
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  • 53
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    Experimental brain research 65 (1986), S. 98-111 
    ISSN: 1432-1106
    Keywords: Cat ; Interneurones ; Motor control ; Jaw movements ; WGA-HRP ; Retrograde transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The location of bulbar neurones with axons projecting to the ipsi- and contralateral trigeminal motor nucleus were investigated in cats anaesthetized with sodium pentobarbital. Wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP) was injected in amounts of 5–24 nl. A volume-calibrated microelectrode was used for recording of evoked potentials and pressure injection of WGA-HRP. The injection site was guided by the position where a maximal antidromic response was evoked by electrical stimulation of the masseteric nerve. The survival time was 19–22 h. In preparations with the depot located in the masseteric subnucleus retrogradely stained neurones were found bilaterally in the borderzone of the trigeminal motor nucleus. Dense populations of stained neurones were observed ipsi- and contralaterally in the dorsal division of the main sensory trigeminal nucleus and the subnucleus-γ of the oral nucleus of the spinal trigeminal tract. Clusters of WGA-HRP-neurones were observed bilaterally in the lateral tegmental field at the level of the subnucleus-β of the oral nucleus of the spinal trigeminal tract, bilaterally dorsal to the facial nucleus and contralaterally adjacent to the hypoglossal nucleus. No stained neurones were found in the gigantocellular reticular nucleus. A group of stained neurones was located in the marginal nucleus of brachium conjunctivum and some were found in the raphé nuclei near obex. Cell profiles were of two types: medium-sized neurones with a triangular profile and 30–40 μm diameter, and fusiform neurones 10×50–70 μm. Convergence of descending cortical and trigeminal afferent inputs on interneurones located in the lateral borderzone of the trigeminal motor nucleus, i.e. the intertrigeminal area, is reported in the preceding paper.
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  • 54
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    Experimental brain research 61 (1986), S. 272-279 
    ISSN: 1432-1106
    Keywords: Membrane property ; Postsynaptic potentials ; Axotomized trigeminal motoneuron ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The membrane properties and the efficacy of excitatory and inhibitory synapses were studied in cat masseteric motoneurons (Mass Mns) after axotomy. In axotomized Mass Mns the slope of the primary range in the frequency-current relationship showed a higher gain than that of normal Mass Mns. The safety of antidromic invasion was increased and the initial segment component of antidromic action potentials could not be separated from the somadendritic component. In normal Mass Mns a single shock delivered to the orbital gyrus or the lingual nerve induced long-lasting inhibitory postsynaptic potentials (IPSPs). In two-thirds of Mass Mns explored 30 days after axotomy, a single shock delivered to the orbital gyrus or the lingual nerve evoked a mixture of inhibitory and excitatory synaptic potentials. In Mass Mns 50 days after axotomy, we have demonstrated that the major fraction of the total sample of explored Mass Mns showed long-lasting excitatory postsynaptic potentials followed by IPSPs. The results suggest that in Mass Mns, axotomy is followed by the decline of synaptic efficacy of inhibitory rather than of excitatory synapses.
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  • 55
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    Experimental brain research 61 (1986), S. 303-310 
    ISSN: 1432-1106
    Keywords: Pyramidal tract axons ; Cat ; Size and morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The purpose of this work was to determine the number and morphology of pyramidal tract (PT) axons in the cat, using electron microscopy, modern methods of fixation, and computer-assisted morphometric analysis. Sections taken at the level of the medullary pyramids in three animals were fixed and magnified up to 10,000 x to produce photomicrographs. Morphological data were entered into computer files for analysis by tracing axon perimeters on micrographs mounted on a digitizer tablet. The number of axons per PT averaged 415,000, of which 88% were myelinated and 12% were unmyelinated. 90% of the myelinated axons fell in the diameter range 0.5–4.5 μm. Axons larger than 9 μm diameter accounted for 1% of the total; the largest were 20–23 μm. Myelinated axon mean diameter was 1.98 μm; because of the skewed distribution, with many small axons and a few very large axons, median diameter was 1.60 μm. Size distribution was relatively uniform throughout the PT cross section, with all sizes represented in all regions. However, the more medial regions had a higher proportion of small fibers than the more lateral regions: mean medial diameter was 1.85 μm while mean lateral diameter was 2.09 μm. Myelin sheath thickness averaged 7.9% of fiber diameter for axons up to 11 μm, but was constant at 0.9 μm for larger fibers. Myelinated fibers were distorted from the circular shape in cross section, with a mean circularity index (or form factor) of 0.85, which implies that the fibers could swell about 15% without rupture of the cell membrane. Unmyelinated fibers averaged 0.18 μm diameter (range 0.05–0.6 μm); the largest unmyelinated axons were larger than the smallest myelinated axons. It is concluded that previous work greatly underestimated the number of axons in the cat pyramidal tract.
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  • 56
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    Experimental brain research 63 (1986), S. 35-48 
    ISSN: 1432-1106
    Keywords: Semicircular canals ; Three-neuron arc ; Vestibulo-ocular reflex ; Horseradish peroxidase ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The morphology of vertical canal related second order vestibular neurons in the cat was studied with the intracellular horseradish peroxidase method. Neurons were identified by their monosynaptic potentials following electrical stimulation via bipolar electrodes implanted into individual semicircular canal ampullae. Anterior and posterior canal neurons projected primarily to contralateral or ipsilateral motoneuron pools (excitatory and inhibitory pathways, respectively). The axons of contralaterally projecting neurons crossed the midline at the level of the abducens nucleus and bifurcated into an ascending and a descending main branch which travelled in the medial longitudinal fasciculus (MLF). Two types of anterior canal neurons were observed, one with unilateral and one with bilateral oculomotor projection sites. For both neuron classes, the major termination sites were in the. contralateral superior rectus and inferior oblique subdivisions of the oculomotor nucleus. In neurons which terminated bilaterally, major collaterals recrossed the midline within the oculomotor nucleus to reach the ipsilateral superior rectus motoneuron pool. Other, less extensive, termination sites of both neuron classes were in the contralateral vestibular nuclear complex, the facial nucleus, the medullary and pontine reticular formation, midline areas within and neighboring the raphé nuclei, and the trochlear nucleus. The ascending main axons continued further rostrally to reach the interstitial nucleus of Cajal and areas around the fasciculus retroflexus. The descending branches proceeded further caudal in the medial vestibulo-spinal tract but were not followed to their spinal target areas. In addition to two previously described posterior canal related neuron types (Graf et al. 1983), we found neurons with bilateral oculomotor terminals and a spinal collateral. Typical for posterior canal neurons, the major termination sites were in the trochlear nucleus (superior oblique motoneurons) and in the inferior rectus subdivision of the oculomotor nucleus. Axon collaterals recrossed the midline to reach ipsilateral inferior rectus motoneurons. The axons of ipsilaterally projecting neurons ascended through the reticular formation to join the MLF caudal to the trochlear nucleus. The main target sites of anterior canal related neurons were in the trochlear nucleus and the inferior rectus subdivision of the oculomotor nucleus. Minor collaterals reached the pontine reticular formation and areas in between the fiber bundles of the ipsilateral MLF. In some cases, small collaterals crossed the midline within the oculomotor nucleus to terminate in the inferior rectus subdivision on the contralateral side. The axon proceeded further rostral to project to the interstitial nucleus of Cajal and beyond. The main termination sites of posterior canal neurons were in the superior rectus and inferior oblique subdivisions of the oculomotor nucleus. Minor collaterals were also observed to reach the midline area within the oculomotor nucleus, however, prospective contralateral termination sites could not be identified. More rostral projections were found in the interstitial nucleus of Cajal. The described axonal arborization of second order vestibular neurons reflects the organization of intrinsic coordinate systems as exemplified by the geometry of the semicircular canal and the extraocular muscle planes. These neurons are interpreted to provide a matrix for coordinate system transformation, i.e. from vestibular into oculomotor reference frames, and to play a role in gaze control and related reflexes by distributing their signals to multiple termination sites.
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  • 57
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    Keywords: Prefrontal cortex ; Limbic cortex ; Medial preoptic area ; Axonal branching ; Electrophysiology ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neurons in cat medial prefrontal cortex, anterior limbic cortex and possibly the indusium griseum were identified by antidromic invasion as having axonal projections towards the medial preoptic region, using both macro- and microstimulation techniques. These projecting axons were found to be of slow conduction velocity (0.2–4.8 m/s) and to in some cases also send branches towards the anteromedial thalamus, mediodorsal thalamus, ventromedial tegmentum, basolateral amygdala or medial forebrain bundle. Threshold-depth curves for axons excited by microstimulation in the medial preoptic region were very steep, with proportionality constants of 0.3–7.1 μm/μA. Calculations based on the threshold-depth curves confirmed that microstimulation was most probably only activating axons within the MPO, and current spread to lateral fibers of passage following macrostimulation in the MPO was not detected in the branching studies.
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  • 58
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    Keywords: Lateral suprasylvian cortex ; Posterior lateral suprasylvian area ; Topography ; Visual field representation ; Scatter of receptive fields ; Cat ; PMLS ; PLLS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have studied the orderliness of representation of visual space in the medial and lateral banks of the middle suprasylvian sulcus. Penetrations were made either parallel to the sulcus, in one bank or the other, or vertical, thus crossing the sulcus between the postero-medial (PMLS) and posterolateral (PLLS) divisions of this area. In some cases we found clear evidence for topographical order in the representation of the visual field with a tendency (greater in PMLS than in PLLS) for the receptive fields of cells recorded deeper in the walls of the sulcus to lie closer to the area centralis, but along many penetrations the receptive fields were so large and so scattered that no retinotopic arrangement could be discerned. In PMLS the receptive fields of the majority of units we studied were centred below and close to the horizontal meridian, whereas in PLLS they were distributed over both the upper and lower visual fields with an over-representation of the upper field. Receptive fields were significantly larger in PLLS (mean field area = 442.2 deg2) than in PMLS (mean area = 154.4 deg2); there was also less clear correlation between receptive field size and eccentricity in PLLS (correlation coefficient = +0.25) than in PMLS (corr. coeff. = +0.72). Analysis of the distance between the receptive field centres of consecutively recorded units demonstrated that the mean scatter in both PMLS and PLLS amounts to about half the average receptive field diameter. In summary the topographical representation of visual space is less orderly in PLLS, and may involve a wider area of the visual field. These findings may relate to the segregated visual cortical and extrageniculate thalamic connections that the medial and lateral banks of the LS receive.
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  • 59
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    Keywords: Locomotion ; Cat ; Hindlimb motoneurons ; Inhibition ; Excitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Intracellular recordings of various motoneurons of proximal hindlimb muscles were performed on thalamic paralyzed cats, during fictive locomotion that was either spontaneous or evoked by stimulation of the subthalamic region. 2. In motoneurons innervating sartorius (medialis and lateralis), vasti (intermedius, medialis and lateralis) and anterior biceps-semimembranous, one depolarization occurred in each locomotor cycle, alternating with a phase of repolarization that was synchronous with the activation of the antagonistic muscle nerve. This latter phase could be decreased or reversed by intracellular injection of chloride ions or current, revealing the presence of inhibitory inputs onto motoneurons. 3. The pattern of membrane potential variations was more complex in motoneurons of rectus femoris and posterior biceps-semitendinosus muscles, but phases of chloride dependent inhibition were nevertheless identified, mainly during the sartorius nerve activation in the case of rectus femoris, and during the vasti and anterior biceps-semimembranosus nerve activations in the case of posterior biceps-semitendinosus. These inhibitory influences were shown to be controlled by the level of activity in exteroceptive afferents. 4. The characteristics of the excitatory and inhibitory inputs to the hindlimb motoneurons identified here are discussed in relation with the organization of the central pattern generator for locomotion.
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    Experimental brain research 64 (1986), S. 233-236 
    ISSN: 1432-1106
    Keywords: Lateral geniculate nucleus ; Orientation bias ; Receptive field ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The orientation sensitivity of LGN cells to flickering square-wave gratings was measured in urethane-anaesthetized paralyzed cats. The mean ratio of the amplitude of peak responses to optimally oriented gratings to that elicited by gratings of the least effective orientation was 3.0 ± 0.3 (S.E.). 58% of the recorded neurons responded best to orientations within 30° of the meridional line joining their receptive field center with the fixation points (area centralis), implying that they were more sensitive to visual contours pointing to the center of the retina.
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  • 61
    ISSN: 1432-2013
    Keywords: Peripheral chemoreceptors ; Central chemoreceptors ; Control of respiration ; Dopamine ; Cat ; Hypercapnia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of exogenous dopamine on the normoxic hypercapnic ventilatory response were assessed in nine chloralose-urethane anesthetized cats using the technique of dynamic end-tidal forcing. The ventilatory responses to step changes in end-tidalP CO 2 (PETCO 2) were measured before (control), during and after intravenous infusion of dopamine (420 μg·kg−1·h−1). Each response was separated into a slow central and a fast peripheral chemoreflex loop by fitting two exponential functions to the measured ventilation. Both loops were described by a CO2 sensitivity, time constant, time delay and a single off-set B (extrapolated PETCO 2, of the steady-state response curve at zero ventilation). Dopamine infusion only caused a significant increase of B (mean 0.3 kPa,P〈0.0001) compared to control; the other model parameters were not significantly affected. After dopamine infusion B returned to significantly lower values (mean 0.2 kPa,P=0.006) than in control. In two additional cats the dopamine administered to the blood which was artificially perfusing the brainstem, did not affect ventilation. We conclude that in normoxic cats the effect of exogenous dopamine on the ventilatory response to CO2 is due to a CO2 independent inhibition of the ventilatory drive which originates outside the brainstem.
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  • 62
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    Pflügers Archiv 406 (1986), S. 419-423 
    ISSN: 1432-2013
    Keywords: Rabbit ; Cat ; Chemoreceptor ; Reserpine ; α-Methyl-p-tyrosine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The response of single chemoafferent fibres to hypoxic and hypercapnic stimulation was studied in vitro under different experimental conditions: 1. control, 2. 24 h after reserpinization (5 mg/kg iv) and 3. 18 h after iv injection of α-methyl-p-tyrosine (100 mg/kg in the rabbit, and 1. control and 2. 24 h after reserpinization (5 mg/kg ip) in the cat. The spontaneous activity was decreased by monoamine depletion. The amplitude of the response to hypoxia and to hypercapnia was decreased by reserpinization in the rabbit and in the cat, the change being less marked in the latter species. Similarly, treatment with·α-methyl-p-tyrosine decreased the ability of chemoreceptors to respond to hypoxia and hypercapnia and, in a few instances, these receptors could only be excited by superfusion of nitrogencquilibrated medium. These results emphasize to possible role of monoamine, and particularly dopamine, in modifying the sensitivity of arterial chemoreceptors to their natural stimuli.
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  • 63
    ISSN: 1432-2013
    Keywords: Lumbar visceral afferents ; Urinary bladder ; Urethra ; Functional properties ; Visceral nociception ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Neural activity of lumbar visceral afferents supplying the urinary bladder and urethra was analyzed systematically in the cat. The afferent fibres were isolated either from the white rami L3 and L4 in a preparation with closed peritoneal cavity, or from the lumbar splanchnic nerves in a preparation with open peritoneal cavity and investigated for various functional parameters. Seventy five single units and 9 multiunit bundles were analyzed. 1) About 50% of the afferent units had some ongoing activity (0.2 to 1 imp/s). Two thirds of the afferent axons were thin myelinated (conduction velocity 3–15 m/s), the rest were presumably unmyelinated (conduction velocity below 2 m/s). 2) The receptive fields of the afferent units consisted —with one exception — of single mechanosensitive sites on the surface of the bladder and urethra. Most receptive fields were situated on the dorsal side of the bladder. 3) Afferents with receptive fields on or in the bladder wall responded in a graded manner to passive distension and isovolumetric contraction at intravesical pressures ranging from about 10 to 70 mm Hg. The thresholds for exciting the afferent units ranged from less than 10 mm Hg to about 30 mm Hg intravesical pressure, most of them being less than 20 mm Hg. Generally, the discharge rate of the afferent units gave a reliable representation of the intravesical pressure to the lumbar spinal cord. 4) Urethral units exhibited either no responses to the graded distensions and contractions of the urinary bladder, or responded with low discharge rates at higher intravesical pressures. 5) The results do not support the notion that noxious events in the urinary bladder are encoded by “specific” nociceptive visceral afferents to the lumbar spinal cord but possibly by some other mechanism of encoding.
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  • 64
    ISSN: 1432-0878
    Keywords: Serotonin-immunoreactive nerve fibers ; Lateral geniculate nucleus ; Immunohistochemistry ; Rat ; Cat ; Monkey (Macaca fuscata)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of serotonin-containing nerve fibers in the lateral geniculate nucleus (LGN) of the rat, cat, and monkey (Macaca fuscata) was studied by use of the peroxidase-antiperoxidase method and an antiserum against serotonin. In all three species, the pattern of fibers was denser in the ventral portion of the LGN (LGNv) than in the dorsal nuclear portion (LGNd). In the LGNd of rat, serotonin-immunoreactive fibers were evenly distributed in the form of a dense network, but in cat and monkey there were marked regional differences. Serotonin-immunoreactive elements were most numerous in the C complex and medial interlaminal nucleus of cat, and in the S layer and interlaminar zones of Macaca fuscata.
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  • 65
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    Cell & tissue research 246 (1986), S. 309-319 
    ISSN: 1432-0878
    Keywords: Muscle spindle ; Sensory innervation ; Mechanosensory transduction ; Morphogenesis ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The arrangement of preterminal and terminal axon branches in the primary sensory endings of cat tenuissimus muscle spindles was studied using whole-mount and serial-section techniques. Although in every case one firstorder preterminal branch was supplied exclusively to the bag1 type of intrafusal muscle fibre, the preterminal branching patterns differed considerably in detail. Terminals varied widely in size and location. Their precise form varied according to their position on the intrafusal muscle fibres rather than their relationship to preterminal branches. Terminals derived from separate preterminal branches remained separate and did not fuse with themselves or each other. Individually bag1 fibres had most terminals, chain fibres least. The surface of the muscle fibres were differentially indented by the terminals, least in bag1 fibres and most in chain fibres. The results are discussed in relation to mechanosensory transduction and to the factors involved in determining the form of the primary ending.
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  • 66
    ISSN: 1432-0878
    Keywords: Amino acid uptake ; Autoradiography ; Salivary gland ; Serine ; Phenylalanine ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Light-microscopic autoradiography was used to localize the cellular sites for neutral amino acid uptake in submandibular and sublingual salivary gland epithelia. The vasculature of isolated glands was perfused for 3–5 min with either L-(3-3H)serine or L-(4-3H)phenylalanine and then fixed by perfusion with buffered glutaraldehyde. In the submandibular gland the small neutral amino acid L-serine and the aromatic amino acid L-phenylalanine were localized to central acinar cells, demilunar cells and ductal cells. In the sublingual gland silver grains associated with each of these tritiated amino acids were localized to central acinar and ductal cells. Perfusion of both submandibular and sublingual glands with unlabelled L-serine (25 mM) or L-phenylalanine (30 mM) resulted in a significant decrease in the silver grain density associated with each labelled amino acid. The absence of silver grains in the lumina of acinar and ductal cells and the presence of tight junctions near the apical surface of the epithelium strongly suggest that the initial uptake of these amino acids was mediated by basolateral plasma membrane carriers.
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  • 67
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    Cell & tissue research 244 (1986), S. 197-202 
    ISSN: 1432-0878
    Keywords: Transverse tubular system ; Sarcoplasmic reticulum ; Triads ; Intrafusal muscle fibre ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A modified staining technique for transverse tubular and sarcoplasmic reticular systems was used to investigate their occurrence in different types of intrafusal muscle fibres in cat tail spindles. Intrafusal muscle fibres can be divided into three basic regions, namely, the periaxial space (A-region), intracapsular area (B-region) and the extracapsular area (C-region); the components of these systems were seen to vary in structure and distribution. The occurrence of these systems also varied among the different types of intrafusal muscle fibres, namely, the bag1, bag2 and chain fibres. In bag1 fibres components were sparse in the A-region, increased slightly in the B-region, but were most developed in the C-region; triads were consistently located at the border between A- and I-bands. In bag2 fibres membrane components were noted in the A-region but were more abundant in the B-region where some tubular components showed transverse and longitudinal branches linked together in the form of a network; membrane systems diminished towards the C-region. The majority of triads were located within the A-bands. In chain fibres the membrane systems occurred more commonly in the A-region, while in the B- and C-regions, the transverse tubular system possessed numerous transverse and longitudinal branches forming irregularly distributed tubular networks. Some tubular branches were dilated, while other branches terminated as sacs among arrays of the sarcoplasmic reticular system in I-bands. Some transverse tubules bifurcated into two branches with numbers of dilated sarcoplasmic reticular cisternae lying on either side, or between, the branches. Triads sometimes occurred between A- and I-bands, but, generally, were situated well within A-bands.
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  • 68
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    European journal of applied physiology 55 (1986), S. 137-141 
    ISSN: 1439-6327
    Keywords: Weight-lifting exercise ; Cat ; Flexor carpi radialis muscle ; Nitric acid digestion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of weight-lifting, which induced muscular enlargement, on fiber number was tested in the flexor carpi radialis muscle by operantly conditioning 6 cats to flex their right wrist against increasing resistance for an average of 101 weeks. The left was used as a control. At the end of training, the cats were performing “one-arm“ lifts with an average of 57% of their body weight. There was an 11% greater muscle weight (P〈0.01) and 9% (P〈0.02) more fibers in the exercised muscles from the right limb than in the left. This study using a different method, supports our earlier observations that prolonged weight-lifting exercise significantly increases the total number of muscle fibers.
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  • 69
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    Experimental brain research 2 (1966), S. 247-260 
    ISSN: 1432-1106
    Keywords: Synaptic excitation ; Hippocampus ; Pyramidal cells ; Dendritic activation ; Cat ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Following selective activation of four afferent paths that terminate exclusively on dendrites, only a small proportion of pyramidal cells in the hippocampal fields CA1 and CA3 discharged impulses. Following a single afferent volley, an EPSP was never observed even in cells synaptically excited. On tetanic stimulation (about 10/sec), a large EPSP developed, but this was not a prerequisite for an action potential. Studies of the extracellular field potentials corresponding to the EPSP and the population spike potential, indicated that the EPSP was generated across the dendritic membrane and that the spike was initiated in the neighbouring part of the dendritic tree, propagating from there along the thicker dendrites towards the soma. This conduction had an average velocity of 0.4m/sec, and, presumably, a relatively low safety factor. In certain cases, the intrasomatic electrode recorded small all-or-nothing spikes which presumably were generated in the dendritic tree. These small spikes (D-spikes) invaded the soma only if assisted by some additional depolarization, for example by frequency potentiation of excitatory synapses. The results indicate two functional types of pyramidal dendrites, the conducting and the synaptic type.
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  • 70
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    Experimental brain research 1 (1966), S. 1-16 
    ISSN: 1432-1106
    Keywords: Inhibitory interneurones ; Cerebellum ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. Extracellular microelectrode recording has been employed to study the responses of three types of interneurones in the cat cerebellar cortex: basket cells, superficial stellate cells and Golgi cells. The large unitary spike potentials of single cells were sharply localized and presumably were generated by impulse discharges from the cell somata. The characteristics of their responses described below sharply distinguished them from Purkinje cells. 2. The parallel fibre volleys generated by surface stimulation of a folium evoked brief repetitive discharges that were graded in respect of frequency and number. Maximum responses had as many as 10 impulses at an initial frequency of 500/sec. 3. At brief test intervals there was facilitation of the response to a second parallel fibre volley; at about 50 msec it passed over to depression for over 500 msec. 4. Stimulation deep in the cerebellum in the region of the fastigial nucleus (juxta-fastigial, J.F.) evoked by synaptic action a single or double discharge, presumably by the mossy fibre-granule cell-parallel fibre path, but climbing fibre stimulation from the inferior olive also usually had a weak excitatory action evoking never more than one impulse. 5. J.F. stimulation also had an inhibitory action on the repetitive discharge evoked by a parallel fibre volley. Possibly this is due to the inhibitory action of impulses in Purkinje cell axon collaterals. 6. There was a slow (7–30/sec) and rather irregular background discharge from all interneurones. The inhibitory actions of parallel fibre and J.F. stimulation silenced this discharge for some hundreds of milliseconds, probably by Golgi cell inhibition of a background mossy fibre input into granule cells. 7. All these various features were displayed by cells at depths from 180 to 500 μ; hence it was concluded that superficial stellate, basket and Golgi cells have similar properties, discrimination being possible only by depth, the respective depth ranges being superficial to 250μ, 250μ to 400μ, and deeper than 400μ.
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  • 71
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    Experimental brain research 1 (1966), S. 17-39 
    ISSN: 1432-1106
    Keywords: Parallel fibres ; Purkinje cells ; Cerebellum ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. When electrical stimuli were applied to the surface of a cerebellar folium by a local electrode (LOC), there was a propagated potential wave along the folium with a triphasic (positive-negative-positive) configuration. 2. Investigations by microelectrode recording established that this wave is produced by impulses propagating for at least 3 mm and at about 0.3 m/sec along a narrow superficial band or “beam” of parallel fibres. As expected from this interpretation, there was an absolutely refractory period of less than 1 msec and impulse annihilation by collision. 3. Complications occurred from the potential wave forms resulting from the excitation of mossy fibres by spreading of the applied LOC stimulus. These complications have been eliminated by chronically deafferenting the cerebellum. 4. When recording within the beam of excited parallel fibres there was a slow negative wave of about 20 msec duration, and deep and lateral thereto, there was a slow positive wave of approximately the same time course. 5. These potential fields were expressed in serial profile plots and in potential contour diagrams and shown to be explicable by the excitatory and inhibitory synaptic action on Purkinje cells: excitatory depolarizing synapses of parallel fibre impulses on the dendrites; and hyperpolarizing inhibitory synapses of stellate and basket cells respectively on the dendrites and somata. The active excitatory synapses would be strictly on the parallel fibre beam and the inhibitory concentrated deep and lateral thereto, which is in conformity with the axonal distributions of those basket and stellate cells that would be excited by the parallel fibre beam. 6. Complex problems were involved in interpretation of slow potentials produced by a second LOC stimulus at brief stimulus intervals and up to 50 msec: there was a potentiation of the slow negative wave, and often depression of the positive wave deep and lateral to the excited beam of parallel fibres. 7. Often the LOC stimulus evoked impulse discharge from the Purkinje cells, these discharges being inhibited by a preceding LOC stimulus.
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  • 72
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    Experimental brain research 1 (1966), S. 48-64 
    ISSN: 1432-1106
    Keywords: Spontaneous post-synaptic potentials (EPSPs, IPSPs) ; Motor cortex ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 1. Im motorischen Cortex von ausgewachsenen Katzen (mittlere Nembutalnarkose) wurden spontane postsynaptische Potentiale (PSP) mit intrazellulären Mikroelektroden untersucht. Die spontanen EPSP wurden mit ausgelösten EPSP nach schwachen Reizen in spezifischen (VL) und unspezifischen (CM) Thalamuskernen verglichen. 2. Spontane EPSP treten entweder einzeln oder gruppiert auf. spontane IPSP sind seltener und machen nur 3–10% aller spontanen PSP aus. Die kleinsten EPSP haben eine Amplitude von 150–200 μV, daneben kommen kleinere, flache Schwankungen des Membranpotentials vor. Die mittlere Amplitude von spontanen EPSP liegt bei 0.7 mV. Amplitudenhistogramme spontaner EPSP unterscheiden sich nicht wesentlich von solchen, die durch schwache CM- oder VL-Reize ausgelöst sind. 3. Die Anstiegssteilheit von spontanen EPSP liegt zwischen 2 und 15 msec. Es besteht keine konstante Beziehung zwischen Amplitude und Anstiegssteilheit. Der Potentialabfall ist annähernd exponentiell, die Zeitkonstante liegt zwischen 8 und 12 msec und ist damit etwas länger als die passive Neuronzeitkonstante (8.5±2.2 msec nach Creutzfeldt u. Mitarb., 1964b). Es bestehen keine konstanten Unterschiede der Zeitverläufe von spontanen, durch VL- oder CM-Reiz ausgelösten EPSP-Einheiten. 4. Die Intervallhistogramme von spontanen EPSP sind verschieden je nach dem, ob alle Intervalle oder nur Perioden mit sporadischer, nicht-gruppierter Aktivität ausgezählt werden. Nicht gruppierte EPSP haben längere mittlere Intervalle (70–80 msec). 5. Nach überschwelligen Thalamusreizserien ist sowohl die spontane als auch die reizinduzierte PSP-aktivität vermindert. Es kann jedoch nicht entschieden werden, inwieweit corticale und inwieweit thalamische Mechanismen für diese post-tetanische Depression verantwortlich sind. 6. Während reversibler Deafferentierung des Cortex durch K+-depolarisation afferenter Fasern und im chronisch isolierten Cortex finden sich keine spontanen PSP mehr, obwohl EPSP und IPSP am isolierten Cortex durch epicorticale Reize noch ausgelöst werden können. 7. Aus den Befunden wird geschlossen, daß die beobachteten PSP durch afferente und collaterale Faseraktivität ausgelöst sind. Für echte „Miniaturpotentiale” entsprechend Beobachtungen an Muskelendplatten findet sich kein Anhalt. Insofern repräsentiert das „synaptische Rauschen” corticaler Zellen die konvergierende Afferenz dieser Zellen und kann nicht als echtes „spontanes Rauschen” angesehen werden.
    Notes: Summary Spontaneous post-synaptic potentials (PSP's) of neurones of the motor cortex are analysed (intracellular recording, Nembutal anesthesia, cats). Distinct EPSP's either appear grouped or more sporadically distributed. Spontaneous EPSP's only represent about 3–10% of all spontaneous PSP's. The mean amplitude of EPSP's is about 0.7 mV. The smallest EPSP's have an amplitude of 150–200 μV, smaller slow fluctuations of the membrane potential (MP) are seen occasionally. Amplitude histograms of spontaneous EPSP's are similar to those of evoked EPSP units following weak thalamic stimulation. — The rising time of spontaneous EPSP's varies between 2 and 15 msec. and is not correlated with the peak amplitude. The decay is almost exponential, the time constant is between 8 and 12msec., thus being slightly higher than the neurone time constant of cortical pyramidal cells (8.5±2.2 msec. Creutzfeldt et al., 1964b). No consistant differences in time course and amplitude of “EPSP units” after VL and CM thalamic stimulation and of spontaneous EPSP's was found. Cortical and thalamic components of post-tetanic depression of spontaneous and evoked PSP activity cannot be distinguished. Interval histograms are different whether all EPSP's during sporadic and grouped activity or whether only sporadically appearing EPSP's are counted. Non-grouped EPSP's show longer mean intervals (between 70 and 80 msec.). — During reversible deafferentation with K+-depolarization of afferent fibers and in the chronically isolated cortex no spontaneous EPSP's or IPSP's are found eventhough membrane fluctuations of cells in the latter preparation may sometimes be difficult to distinguish from real EPSP's. In the chronically isolated cortex, EPSP's and IPSP's can still be elicited by epicortical stimulation. — From these findings it is concluded that the observed spontaneous PSP's represent “unit” EPSP's and IPSP's due to afferent and collateral fiber activity and that no true miniature potentials due to spontaneous liberation of transmitter substance can be recorded. Thus, the “synaptic noise” of cortical neurones represents convergent activity on these cells and consequently cannot be considered as true “spontaneous noise”.
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