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  • 1
    ISSN: 1432-1106
    Keywords: Fluorescent retrograde labeling ; Cerebellar nuclei ; Antidromic stimulation ; Branching neurons ; Double labeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In cat the existence of collaterals from deep cerebellar neurons, which project to mesencephalon and thalamus has been investigated anatomically by means of the multiple retrograde fluorescent tracer technique as well as electrophysiologically by means of conventional antidromic techniques. Both sets of data indicate that several neurons in the medial nucleus, which project to mesencephalon and thalamus, also distribute collaterals to medulla oblongata and spinal cord. These branching neurons were principally located in the caudal and intermediate portions of the medial nucleus. The electrophysiological data in addition indicate that the branching point of the neurons in the medial nucleus is located relatively close to the cell soma. The anatomical findings show a further group of branching neurons in the lateral nucleus at the border with the interpositus nuclei. The majority of these latter neurons distribute collaterals to medulla oblongata but some distribute collaterals to spinal cord. However, it could not be decided as yet whether the collaterals to the medulla oblongata terminate either in medullary medial reticular formation or in inferior olive or in both.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1106
    Keywords: Arm movements ; Arcuate sulcus ; Visuo-motor system ; Cortex ; Monkey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neuron activity was recorded in monkey cerebral cortex during a visually guided reaching task. Cells located in the banks of the arcuate sulcus at its curvature changed their activity during the period in which the monkey saw a food reward in a certain position, but before it moved to retrieve the reward. A role of these neurons in visual guidance of arm and hand movements is postulated.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1106
    Keywords: Callosum ; Cortex ; Fluorescent retrograde tracing ; Electrophysiology ; Corticospinal branching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In rat the presence of axon collaterals from corticospinal neurons to the contralateral hemisphere has been investigated by means of anatomical and electrophysiological techniques. Anatomical Experiments. Several combinations of fluorescent retrograde tracers were used. In eight rats injections of Evans Blue, “True Blue”, “Fast Blue” or DAPI-Primuline were made in areas 10, 6, and 4 and in the most medial part of the S1 granular cortex of one hemisphere, 1.5 mm below cortical surface. These injections were combined with injections of “Fast Blue”, DAPI-Primuline, “Granular Blue”, “Nuclear Yellow”, or Bisbenzimide in the ipsilateral corticospinal tract in the C2 segment. Survival times of the animals varied according to the tracers used. In the non-injected hemisphere the retrogradely labeled corticospinal neurons were present in layer V of especially areas 10, 6, 4 and the medial portion of the S1 granular cortex. However, the retrogradely labeled callosal neurons in these areas were present in all layers except layer I. The labeled callosal and corticospinal neurons in layer V were intermingled and frequently situated very close to one another. However, with none of the tracer combinations were double labeled neurons observed. Electrophysiological Experiments. In six rats, layer V neurons of hindlimb-sensorimotor cortex were tested for antidromic responses to stimulation of contralateral corticospinal tract (CST) and corpus callosum (CC). Eighty-five CST neurons were identified, none of which responded antidromically to CC shocks. Eighty-two layer V neurons were identified which responded antidromically to CC shocks, but none of them responded antidromically to CST shocks. CC shocks elicited strong synaptic responses in CST neurons and vice versa. Depth measures indicated extensive intermingling of CST and CC neurons. From both sets of findings it was concluded that, in rat, CST neurons do not give rise to callosal collaterals.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1106
    Keywords: Cortex ; Monkey ; Postarcuate area ; Premotor area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A study has been made of the corticocortical efferent and afferent connections of the posterior bank of the arcuate sulcus in the macaque monkey. The distribution of efferent projections to the primary motor cortex (MI) was studied by injecting three different fluorescent retrograde tracers into separate regions of MI. The resultant labeling showed a discrete and topographically organized projection: neurons lying below the inferior limb of the arcuate sulcus project into the MI face area, while neurons located in the posterior bank of the inferior limb of the arcuate sulcus and in the arcuate spur region project into the MI hand area. These findings were confirmed electrophysiologically by demonstrating that postarcuate neurons could only be activated antidromically by stimulation within restricted regions of MI. HRP injections within postarcuate cortex indicated that afferents to this region arise from a number of cortical areas. However, the largest numbers of labeled neurons were found in the posterior parietal cortex (area 7b; PF) and in the secondary somatosensory region (SII). Neurons in both 7b (PF) and SII could be antidromically activated by postarcuate stimulation. It was further shown that stimulation of area 7b (PF) gives rise to short-latency synaptic responses in postarcuate neurons, including some neurons with identified projections to MI. The results are discussed in relation to the possible function of the postarcuate region of the premotor cortex in the sensory guidance of movement.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1106
    Keywords: Meynert cells ; Monkey visual cortex ; Superior colliculus ; Axon collateralization ; Double labelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Layer VI of macaque striate cortex contains a number of large solitary neurones called Meynert cells. It has been shown earlier that these Meynert cells project to the posterior bank of the superior temporal sulcus (area V5), but it has also been shown that they project to the superior colliculus. In retrograde fluorescent double-labelling experiments, it was found that Meynert cells represent a class of neurones which distribute divergent axon collaterals to the posterior bank of the superior temporal sulcus and to the superior colliculus, i.e. to a distant cortical and a subcortical structure. This feature appears to be unique among projecting neurones in monkey visual cortex.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 68 (1987), S. 565-578 
    ISSN: 1432-1106
    Keywords: Retrograde fluorescent double labeling ; Branching neurons ; Descending propriospinal neurons ; Ascending propriospinal neurons ; Ascending supraspinal neurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Branching neurons giving rise to ascending and descending collaterals were studied in the cervical spinal cord of the rat. After unilateral injection of two retrograde fluorescent tracers, i.e. DY.2HCl at T2 or more caudal levels and TB at C1 or more rostral levels, many DY-TB double-labeled neurons were found in C3 to C8. These neurons were located bilaterally throughout the spinal grey matter, as well as in the lateral spinal nucleus (LSN). However, no double-labeled neurons could be detected in the laminae I and II on either side. The double-labeled neurons must represent branching neurons giving rise to a collateral ascending to the rostral injection-site or above, and another collateral descending to the caudal injection-site or below. The descending collaterals were found to extend to various spinal levels, including the lumbosacral cord. However, most of them terminated at shorter distances from their parent cell bodies; thus 20% of the C3–C8 neurons projecting to C1 or above had a descending collateral reaching T2, 8% had a collateral reaching T9, and 3% a collateral reaching L2/L3. The ascending collaterals of the majority of the branching neurons passed into the most caudal part of the medulla oblongata, and about half of these collaterals reached the level of the rostral part of the inferior olive. In regard to the neurons located in the segments C5–C8, about 13% of those projecting to T2 or below distribute an ascending collateral restricted to C2–C4, while 29% of those had an ascending collateral to C1 or above.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1106
    Keywords: Fluorescent retrograde tracers ; Diamidino Yellow·2HCl ; Retrograde double labeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Earlier studies showed that Nuclear Yellow (NY), True Blue (TB) and Fast Blue (FB) are transported retrogradely through axons to their parent cell bodies. NY produces a yellow fluorescent labeling of the neuronal nucleus at 360 nm excitation wavelength, while TB and FB produce a blue fluorescence of the cytoplasm at this same wavelength. Therefore, NY may be combined with TB or FB in double-labeling experiments demonstrating the existence of axon collaterals. However, retrograde neuronal labeling with TB or FB requires a relatively long survival time, while NY requires a short survival time since NY migrates rapidly out of the retrogradely labeled neurons. This complicates double-labeling experiments since TB and FB must be injected first and NY later, a short time before the animal is sacrificed. We report a new yellow fluorescent tracer which labels mainly the nucleus and migrates much more slowly out of the retrogradely labeled neurons than NY. This new tracer can be used instead of NY in combination with TB or FB in double-labeling experiments and unlike NY can be injected at the same time as TB or FB. The new tracer is a diamidino compound (no. 28826) which is commercially Distributed by Dr. Illing KG, Warthweg 14-18, Postfach 1150, D-6114 Groß-Umstadt, FRG available. It will be referred to as Diamidino Yellow Dihydrochloride (DY·2HCl). According to the present study DY·2HCl is transported over long distances in rat and cat, and produces a yellow fluorescence of the neuronal nucleus at 360 nm excitation wavelength, resembling that obtained with NY. When combined with TB or FB, DY·2HCl is as effective as NY in double labeling of neurons by way of divergent axon collaterals.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 54 (1984), S. 107-120 
    ISSN: 1432-1106
    Keywords: Corticospinal collaterals ; Sensorimotor cortex ; Corticobulbar pathways ; Fluorescent tracers ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The fluorescent retrograde double-labeling technique has been used to determine whether corticospinal neurons in the cat sensorimotor cortex distribute collaterals to the lower brain stem reticular formation. In this study the fluorescent tracers Nuclear Yellow and Diamidino Yellow 2HCl were used in combination with Fast Blue. One tracer was injected unilaterally in the spinal cord and the other was injected ipsilaterally in the bulbar medial reticular formation. The distribution of the retrogradely labeled neurons was studied in the contralateral hemisphere. In the sensorimotor cortex a large population of neurons was found which were labeled from the spinal cord and were double-labeled from the brain stem. These branching neurons were concentrated in the rostromedial part of area 4 and the adjoining lateral part of area 6. In this region the percentages of corticospinal neurons which were double-labeled from the brain stem ranged from 5% laterally to 30% medially. In two cats it was demonstrated by means of the anterograde transport of HRP that the corticobulbar fibers from this region which must include the corticospinal collaterals are distributed to the reticular formation of the lower brain stem. In view of the fact that the double-labeled neurons are concentrated in the anterior part of the motor cortex, those branching neurons are in all likelihood involved in the control of neck, back and shoulder movements. This control is probably exerted by way of two routes i.e. by way of the direct corticospinal connections to spinal interneurons, and by way of the indirect cortico-reticulospinal connections established by the cortical fibers to the bulbar reticular formation. The present findings suggest that this dual control may be exerted by one and the same cell.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1106
    Keywords: Corticopontine collaterals ; Corticotectal neurons ; Cortex ; Cat ; Fluorescent tracers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The fluorescent double-labeling technique has been used to determine whether the corticopontine and the corticotectal fibers in the cat are derived from two different sets of neurons or whether they are derived from branching neurons which distribute collaterals to the pontine grey and the colliculi. After unilateral DY.2HCl injections in the pontine grey and FB injections in the ipsilateral colliculi, large numbers of FB-DY.2HCl double-labeled neurons were present in the cortex of the ipsilateral hemisphere. However, the labeled neurons in its rostral part may have represented pyramidal tract neurons which were labeled retrogradely because their fibers descended through the DY.2HCl injection area. Therefore, also DY.2HCl injections were made in the pyramid (i.e. caudal to the pons) and the cortical pyramidal tract area, containing the retrograde DY.2HCl-labeled neurons, was delineated. In the rest of the experiments only the DY.2HCl-labeled neurons in the caudal two thirds of the hemisphere (outside the pyramidal tract area) were taken into account because only these neurons could, with confidence, be regarded as corticopontine neurons. In some anterograde HRP transport experiments the trajectories of the corticotectal and the corticopontine fibers were visualized. On the basis of the findings the DY.2HCl injections in the pontine grey were placed such that they could not involve any of the corticotectal fibers passing from the cerebral peduncle to the colliculi. Thus artifactual doublelabeling of cortical neurons was avoided. However, also under these circumstances many double-labeled neurons were present in the caudal two thirds of the hemisphere. This led to the conclusion that in the cat a large proportion of the corticopontine neurons in the caudal two thirds of the hemisphere represent branching neurons which also distribute collaterals to the colliculi. The parietal (anterior part of the lateral gyrus, middle and posterior suprasylvian gyri) and the cingulate areas together contained three quarters of all labeled corticopontine neurons outside the pyramidal tract area. In the parietal areas roughly 25% of them were double-labeled and in the cingulate area 14%. However, in the visual areas 18 and 19 a much larger percentage (30–60%) was doublelabeled. In a recent study from our laboratory it was found that in the cat the pyramidal tract fibers distribute an abundance of collaterals to the pontine grey. Therefore, a large proportion of all corticopontine connections in this species appear to be established by branching neurons which also distribute fibers to other cell groups in the brain stem and the spinal cord.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 46 (1982), S. 339-356 
    ISSN: 1432-1106
    Keywords: Cerebellar nuclei ; Axon collaterals ; Cerebellar efferents ; Double labeling ; Fluorescent tracers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The existence of divergent axon collaterals of neurons in the deep cerebellar nuclei has been investigated in rat by means of the fluorescent retrograde double labeling technique. The results have led to the following conclusions. A. Many of the neurons in the lateral, the interpositus as well as the caudal half of the medial nucleus project to the diencephalon. Some of these neurons distribute divergent axon collaterals to the superior colliculus, but few neurons project only to the latter structure. B. Some of the deep cerebellar neurons located laterally, i.e. in the dorsomedial part of the lateral nucleus, as well as some others located medially, i. e. in the medial part of the interpositus nucleus and the adjoining part of the medial nucleus, distribute divergent axon collaterals to the diencephalon and the spinal cord. C. Deep cerebellar neurons located laterally: in the cell group of the dorsolateral hump (Dlh) and in the adjoining lateral part of the interpositus nucleus, as well as some others located medially, i.e. in the dorsolateral part of the medial nucleus (Mdlp), distribute divergent axon collaterals to the diencephalon and to the medulla oblongata, probably primarily its medial reticular formation. However, only few of the neurons, which distribute descending collaterals to the spinal cord or the medulla oblongata, distribute ascending collaterals to the superior colliculus. D. After injections in the medulla oblongata a population of small sized single labeled neurons was encountered especially in the lateral and interpositus nuclei. On the basis of other findings in rat they were assumed to represent cerebello-olivary neurons.
    Type of Medium: Electronic Resource
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