Neuroscience
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The preganglionic sympathetic neurons in the intermediolateral cell column of the thoracic and upper lumbar segments of the spinal cord which innervate the chromaffin cells in the adrenal medulla, sympathoadrenal preganglionic neurons, were identified by the method of retrograde axonal transport of the fluorescent dyes Fast Blue and True Blue. In rats, Fast Blue or True Blue was injected into the medulla of the left adrenal gland. After a survival period of 5 days, the animals were perfusion fixed, the thoracic and lumbar spinal cord sectioned and processed for the immunofluorescent localization of met-enkephalin, neurophysin, oxytocin, serotonin, somatostatin and substance P immunoreactivity. ⋯ Serotonin immunoreactivity was depleted in the intermediolateral cell column below the level of the transection for five to six segments, but sparse networks of immunoreactive fibers were observed in both the intermediolateral cell column and the ventral horn in more caudal segments. Met-enkephalin, serotonin, somatostatin and substance P immunoreactivity were decreased in both the contralateral and ipsilateral intermediolateral cell column below the level of a spinal cord hemisection, suggesting that both crossed and uncrossed descending pathways exist. Neurophysin and oxytocin immunoreactivity were depleted below the level of the hemisection in the ipsilateral intermediolateral cell column without noticeable decrease in the level of immunoreactivity in the contralateral intermediolateral cell column, suggesting that a decussation does not occur at the level of the spinal cord, but may exist above the level of the hemisection...
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Both systemic and intrathecal capsaicin release and deplete substance P from primary sensory afferents and induce prolonged chemical and thermal analgesia. Given the existence of efferents containing substance P together with a pain-inhibitory serotoninergic pathway, the present study investigated the effects of intraventricular capsaicin upon basal nociception, analgesic responsivity to opiates and substance P immunoreactivity. Following treatment with capsaicin at doses of 25, 50 and 100 micrograms or with vehicle, alterations in basal rodent flinch-jump thresholds as well as analgesic responses to 5 and 2.5 mg/kg of morphine were measured over a post-injection time course. ⋯ Substance P-like immunoreactivity in capsaicin-treated rats was not appreciably depleted compared with vehicle controls in the substantia gelatinosa of the spinal cord and V cranial nerve, the raphe magnus and periaqueductal gray, the medullary, pontine and mesencephalic reticular formation, the substantia nigra, the corpus striatum and the central nucleus of the amygdala. By contrast, substance P-like immunoreactivity appeared to increase in the medial nucleus of the amygdala. In the absence of depletion of substance P immunoreactivity by the intraventricular capsaicin, the observed alterations in opiate analgesic responses may possibly be due to alterations in other transmitters or peptide systems.
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The relation between figural and kimematic aspects of movement was studied in handwriting and drawing. It was found that, throughout the movement, the tangential velocity. V is proportional to the radius of curvature r of the trajectory: V= kr, or, equivalently, that the angular velocity is constant: dalpha(t)/dt = K. ⋯ This organisational principle holds even when movements are mechanically constrained or are executed under strict visuo-motor guidance. Moreover, the segmentation of a given trajectory is invariant with respect to the total duration of the movement. A tentative interpretation of the principle is proposed which results from the assumption that the actual movement is produced as a continuous approximation to an intended movement, and that the well known relationship between movement speed and extent in rectilinear trajectories (Fitts' law) also applies to such continuous approximation.
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Comparative Study
Efferent connections of dorsal and ventral agranular insular cortex in the hamster, Mesocricetus auratus.
The anterior portion of rodent agranular insular cortex consists of a ventral periallocortical region (AIv) and a dorsal proisocortical region (AId). Each of these two cortical areas has distinct efferent connections, but in certain brain areas their projection fields are partially or wholly overlapping. Bilateral projections to layers I, III and VI of medial frontal cortex originate in the dorsal agranular insular cortex and terminate in the prelimbic, anterior cingulate and medial precentral areas; those originating in ventral agranular insular cortex terminate in the medial orbital, infralimbic and prelimbic areas. ⋯ Brainstem areas receiving projections from the ventral and dorsal regions include the lateral hypothalamus, substantia nigra pars compacta, ventral tegmental area and dorsal raphe nucleus. In addition, the ventral region projects to the periaqueductal gray and the dorsal region projects to the parabrachial and ventral pontine nuclei. These efferent connections largely reciprocate the afferent connections of the ventral and dorsal agranular insular cortex, and provide further support for the concept that these regions are portions of an outer ring of limbic cortex which plays a critical role in the expression of motivated, species-typical behaviors.