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  • 1
    Electronic Resource
    Electronic Resource
    REGIONAL BRAIN ACTIVATION IN HUMANS DURING RESPIRATORY AND BLOOD PRESSURE CHALLENGES (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 25 (1998), S. 0 
    Details
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. The aim of the present study was to determine the brain sites mediating aspects of respiratory and cardiovascular control in adult humans using non-invasive functional magnetic resonance (/MRI) procedures, thereby avoiding the spatial and temporal sampling limitations associated with classic neural assessment techniques.2. We examined activity changes across the entire brain following application of respiratory loads and upon induction of blood pressure and heart rate alterations. Magnetic resonance signals were visualized with a 1.5Tesla scanner in healthy volunteers (22-52 years of age) using procedures that optimally assess changes in brain tissue microcirculation. Images were collected during a Valsalva manoeuvre, inspiratory loading, hypercapnia, cold pressor challenges to the hand and forehead and during intervening baseline states.3. Image values from experimental conditions were compared with corresponding baseline values on a pixel-by-pixel basis to identify brain regions in which the experimental conditions produced physiological activation.4. Ventilatory and pressor challenges elicited significant changes in regional image signal intensity in areas within the orbital cortex, amygdala, hypothalamus and hippocampus. Cerebellar, medullary and pontine areas were also recruited. However, while particular brain regions were only activated during specific stimuli, other regional signal changes occurred with multiple experimental manipulations.5. The findings indicate that respiratory and cardiac challenges elicit discrete activity changes over multiple brain sites. Activated regions include structures not often related to respiratory or cardiovascular regulation, such as the cerebellum; a prominent role for limbic forebrain structures in mediating the response is also suggested. The f MRI visualization procedures may greatly assist in the determination of neural structures that mediate respiratory and cardiovascular control in humans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1681.1998.tb02240.x
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  • 2
    Electronic Resource
    Electronic Resource
    A subpopulation of rats show social and sleep–waking changes typical of chronic neuropathic pain following peripheral nerve injury (2003)
    Oxford, UK : Blackwell Science, Ltd
    European journal of neuroscience 17 (2003), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Neuropathic conditions for which treatment is sought, the so-called chronic pain syndrome, are characterized usually by complex behavioural disturbances as well as pain. In this study we evaluated whether social behavioural and sleep disruptions occurred after nerve injury. Before and after chronic constriction of the sciatic nerve, resident–intruder and sleep–wake cycles, as well as mechanical and thermal allodynia/hyperalgesia, were quantified. Sciatic nerve injury in all animals reduced withdrawal thresholds to tactile and thermal (cold) stimuli. Resident–intruder and sleep–waking behaviours were altered in some but not all animals. One group (30%, ‘persistent change’) had enduring reductions in dominant behaviour to an intruder and decreased slow-wave sleep and increased wakefulness during both light and dark cycles. Another group (25%, ‘recovery’) had a transient reduction in dominant behaviours and decreased slow-wave sleep and increased wakefulness during only the light cycle. In a third group (45%, ‘no effect’) resident–intruder and sleep–waking behaviours remained normal. Our finding that the degree of ‘pain’ as inferred from the allodynia/hyperalgesia was identical in all animals suggests that the alterations to resident–intruder and sleep–wake cycles were independent of the level of sensory disturbance. An absence of correlation between intensity of sensory disturbances and measures of disability (loss of sleep, familial/social problems) is also characteristic of human neuropathic pain. These data indicate that: (i) in a subpopulation of animals sciatic injury results in two of the major complex behavioural changes which are characteristic of neuropathic pain in humans; (ii) testing only for allodynia and hyperalgesia is not sufficient to detect this subpopulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.2003.02627.x
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  • 3
    Electronic Resource
    Electronic Resource
    Somatic and visceral afferents to the ‘vasodepressor region’ of the caudal midline medulla in the rat (2003)
    Oxford, UK : Blackwell Science, Ltd
    European journal of neuroscience 17 (2003), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Previous research has found that the integrity of a restricted region of the caudal midline medulla (including caudal portions of nucleus raphé obscurus and nucleus raphé pallidus) was critical for vasodepression (hypotension, bradycardia, decreased cardiac contractility) evoked either by haemorrhage or deep pain. In this anatomical tracing study we found that the vasodepressor part of the caudal midline medulla (CMM) receives inputs arising from spinal cord, spinal trigeminal nucleus (SpV) and nucleus of the solitary tract (NTS). Specifically: (i) a spinal–CMM projection arises from neurons of the deep dorsal horn, medial ventral horn and lamina X at all spinal segmental levels, with approximately 60% of the projection originating from the upper cervical spinal cord (C1–C4); (ii) a SpV–CMM projection arises primarily from neurons at the transition between subnucleus caudalis and subnucleus interpolaris; (iii) a NTS–CMM projection arises primarily from neurons in ventrolateral and medial subnuclei. In combination, the specific spinal, SpV and NTS regions which project to the CMM receive the complete range of somatic and visceral afferents known to trigger vasodepression. The role(s) of each specific projection is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.2003.02535.x
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  • 4
    Electronic Resource
    Electronic Resource
    Haemorrhage-evoked decompensation and recompensation mediated by distinct projections from rostral and caudal midline medulla in the rat (2004)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 20 (2004), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The haemodynamic response to blood loss consists of three phases: (i) an initial compensatory phase during which resting arterial pressure is maintained; (ii) a decompensatory phase characterized by a sudden, life-threatening hypotension and bradycardia; and (iii) if blood loss ceases, a recompensatory phase during which arterial pressure returns to normal. Previous research indicates that topographically distinct, rostral and caudal parts of the caudal midline medulla (CMM) contain neurons that differentially regulate the timing and magnitude of each of the three phases. Specifically, decompensation depends critically on the integrity of the rostral CMM; whereas compensation and recompensation depend upon the integrity of the caudal CMM. This study aimed to determine, using retrograde and anterograde tracing techniques, if the rostral and caudal CMM gave rise to different sets of projections to the major cardiovascular region of the ventrolateral medulla (VLM) and spinal cord. It was found that rostral and caudal CMM each have projections of varying density to the region containing bulbospinal (presympathetic) motor neurons in the rostral VLM and preganglionic sympathetic motor neurons in the intermediolateral cell column of the spinal cord. Via these projections vasomotor tone and hence arterial pressure can be regulated. More strikingly: (i) consistent with a role in mediating bradycardia during decompensation, the rostral CMM projects uniquely to VLM regions containing vagal cardiac motor neurons; and (ii) consistent with its role in mediating recompensation, the caudal CMM projects uniquely onto tyrosine hydroxylase-containing, caudal VLM (A1) neurons whose activity mediates vasopressin release, on which recompensation depends.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.2004.03660.x
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  • 5
    Electronic Resource
    Electronic Resource
    Facilitation of Aggressive Behaviour in Rat by Direct Cholinergic Stimulation of the Hypothalamus (1969)
    [s.l.] : Nature Publishing Group
    Nature 224 (1969), S. 1035-1036 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] I have examined the effects of direct adrenergic and cholinergic stimulation of the lateral hypothalamus on predatory aggression in the rat. A recent finding that most male hooded rats kill frogs but not mice (unpublished work of myself and K. E. Mover) permitted a test for both the facilitation ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/2241035a0
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  • 6
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    Changes in Sensory and Motor Systems during Centrally Elicited Attack (1971)
    Baltimore, Md. : Periodicals Archive Online (PAO)
    Behavioral science. 16:1 (1971:Jan.) 1 
    Details
    ISSN: 0005-7940
    Topics: Psychology
    Notes: THE BIOLOGY OF MENTAL HEALTH AND DISEASE - A SYMPOSIUM
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:5019-1971-016-01-000001
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  • 7
    Electronic Resource
    Electronic Resource
    Quiescence and hyporeactivity evoked by activation of cell bodies in the ventrolateral midbrain periaqueductal gray of the rat (1994)
    Springer
    Experimental brain research 99 (1994), S. 75-83 
    Details
    ISSN: 1432-1106
    Keywords: Periaqueductal gray ; Stress ; Defense Passive coping behavior ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Much evidence suggests that the midbrain periaqueductal gray region (PAG) plays a pivotal role in mediating an animal's responses to threatening, stressful, or painful stimuli. Active defensive reactions, hypertension, tachycardia and tachypnea are coordinated by a longitudinally oriented column of cells, found lateral to the midbrain aqueduct, in the caudal two-thirds of the PAG. In contrast, microinjections of excitatory amino acid (EAA) made in the ventrolateral region of the PAG in anesthetized or isolated animals evoke hypotension, bradycardia, and behavioral arrest. The aim of the present study was to examine further the effects of activation of neurons in the ventrolateral PAG. By injecting into this region low doses (40 pmol) of kainic acid (KA), a long-acting EAA, it was possible to observe a freely moving rat's behavior in a social situation (i.e., paired with a weight-matched, untreated partner). Such injected rats become quiescent, i.e., there was a cessation of all ongoing spontaneous activity. These rats were also hyporeactive: the investigative approaches of the partner failed to evoke orientation, startle reactions, or vocalization. Electroencephalographic measurements indicated that the effects of injections of KA in the ventrolateral PAG were not secondary to seizure activity. In addition to the quiescence and hyporeactivity reported here, and the hypotension and bradycardia reported previously, the ventrolateral PAG is a part of the brain from which analgesia has been readily evoked by electrical stimulation, or microinjections of either EAA or morphine. As a reaction to “deep” or “inescapable” pain, chronic injury, or defeat, animals often reduce their somatomotor activity, become more solitary, and are generally much less responsive to their environment. These data, and those from other recent studies, suggest that neurons in the ventrolateral PAG may play an important role in integrating such a passive behavioral response of which quiescence and hyporeactivity are the major components.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241413
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  • 8
    Electronic Resource
    Electronic Resource
    Longitudinal neuronal organization of defensive reactions in the midbrain periaqueductal gray region of the rat (1992)
    Springer
    Experimental brain research 90 (1992), S. 307-318 
    Details
    ISSN: 1432-1106
    Keywords: Periaqueductal gray matter ; Defensive behavior ; Excitatory amino acids ; Freezing ; Hypertensive reaction ; Ultrasonic vocalization ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In a previous study we investigated the intraspecific defensive reactions evoked by excitation of neurons in the intermediate third of the midbrain periaqueductal gray matter (PAG) of the rat. Experiments revealed that activation of neurons in this region of the PAG mediated: (i) backward defensive behavior, characterized by upright postures and backward movements, and (ii) reactive immobility (“freezing”), in which the rat remained immobile, but reacted with backward defensive behavior to investigative, non-aggressive contact initiated by the partner. In the present study, we aimed to extend our understanding of PAG mediation of defensive behavior by observing: (i) in a non-aggressive social interaction test, the behavioral effects of microinjections of low doses of kainic acid (40 pmol in 200 nl) made in the caudal third of the PAG; and (ii) the behavioral and cardiovascular effects of microinjections of d, l-homocysteic acid (5–10 nmol in 50–100 nl) made in the PAG of the unanesthetized decerebrate rat. Kainic acid injections into the area lateral to the midbrain aqueduct in the caudal third of the PAG evoked: (i) forward avoidance behavior, characterized by forward locomotion and occasional hop/jumps; (ii) reactive immobility (“freezing”), in which the rat remained immobile, but reacted with forward avoidance behavior to investigative, non-aggressive contact initiated by the partner; and (iii) 22–28 kHz ultrasonic vocalizations. These injections also evoked a dramatic increase in defensive responsiveness to tactile stimuli on the half of the body contralateral, but not ipsilateral, to the site of injection. Electroencephalographic measurements indicated that none of these effects were secondary to seizure activity. In the decerebrate rat, d, l-homocysteic acid injections in the caudal third of the PAG evoked forward running movements along with increased blood pressure and heart rate, the strongest effects being evoked from the region lateral to the midbrain aqueduct. More rostrally, sites in the intermediate PAG evoked backward “defensive” movements, which were also associated with increased blood pressure and heart rate. These data, along with those from our previous study in the rat indicate that: (i) defensive reactions are integrated within a longitudinal neuronal column which spans the caudal two thirds of the lateral PAG; (ii) the lateral PAG “defensive behavior” column contains two distinct populations of neurons, one within the intermediate lateral PAG which integrates defensive behavior characterized by facing towards and backing away from a “threatening” stimulus, and a second in the caudal lateral PAG which integrates defensive behavior characterized by forward avoidance behavior; and (iii) neurons within the lateral PAG couple strong cardiovascular changes with each distinctive defensive behavior pattern. The emerging view from this and recent studies of this midbrain region in other species, suggests that similar rostrocaudal differences within a longitudinally oriented lateral PAG neuronal column represent a fundamental principle underlying the PAG organization of defensive behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227243
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  • 9
    Electronic Resource
    Electronic Resource
    Finding the failure mechanism in Sudden Infant Death Syndrome (1998)
    [s.l.] : Nature Publishing Group
    Nature medicine 4 (1998), S. 157-158 
    Details
    ISSN: 1546-170X
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] THE SUDDEN INFANT Death Syndrome (SIDS)—the death of an infant that remains unexplained after an autopsy and death scene investigation—is a principal cause of death among infants less than a year old in developed countries. SIDS is temporally related to periods of sleep and its ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nm0298-157
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