SEROTONERGIC MODULATION OF SOMATOSENSORY ACTIVITY AT THE LEVEL OF THE THALAMUS OF THE RAT (VB COMPLEX, POSTERIOR, IMMUNOCYTOCHEMISTRY).
Item
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Title
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SEROTONERGIC MODULATION OF SOMATOSENSORY ACTIVITY AT THE LEVEL OF THE THALAMUS OF THE RAT (VB COMPLEX, POSTERIOR, IMMUNOCYTOCHEMISTRY).
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Identifier
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AAI8515614
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identifier
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8515614
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Creator
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CROPPER, ELIZABETH CAROL.
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Contributor
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Joseph S. Eisenman
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Date
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1985
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, General
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Abstract
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The purpose of this project was to determine whether there is evidence for serotonergic modulation of somatosensory activity at the level of the thalamus of the rat, and, if so, if there is a difference in modulatory effects exerted on nonnociceptive and nociceptive activity.;Serotonin immunocytochemistry, and extracellular recording techniques, were used to map the distribution of serotonin immunoreactive fibers, in somatosensory regions of the thalamus, and physiologically characterize regions, with different densities of innervation. The ventrobasal (VB) complex, the primary relay for somatotopically organized nonnociceptive information, contained few immunoreactive fibers. Posterior regions of the thalamus, where nonsomatotopically organized responses to nociceptive stimulation were more commonly recorded than responses to nonnociceptive stimulation, contained a moderate number of immunoreactive fibers.;Microiontophoretic techniques were also used to apply serotonin to units responding to nociceptive and nonnociceptive stimulation, in the VB complex, and in posterior regions of the thalamus. Continuous ratemeter plots of unit activity, averaged over 1 sec intervals, were used to monitor serotonergic effects on neuronal firing frequency. The spontaneous activity of 10/10 nonnociceptive, and 13/13 nociceptive, and the evoked activity of 16/16 nociceptive, and 6/7 nonnociceptive units was inhibited. Also using microiontophoretic techniques, the time course of responses to nonnociceptive stimulation was examined, and the effects of serotonin on different response components determined. Iontophoretic application of serotonin inhibited the phasic response components of 10/11 units tested, and the tonic response component of 5/5 units tested. Percent decreases in phasic response components were less than percent decreases in tonic components, when the effect of iontophoretic application of serotonin on components of the same response were determined.;These experiments indicate that there are serotonergic fibers in thalamic nuclei, particularly in posterior thalamic regions associated with transmission of nociceptive activity, and that serotonin can exert an inhibitory effect on somatosensory transmission.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Biomedical Sciences
