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Showing papers on "Somatosensory system published in 1984"


Journal ArticleDOI
TL;DR: The results of this study indicate that neuronal activity in the putamen is predominantly related to the direction of limb movement rather than to the activity of particular muscles and that the basal ganglia may play a role in the specification of parameters of movement independent of theActivity of specific muscles.
Abstract: In order to clarify the functional organization of the putamen and the nature of sensory inputs to this structure we studied the relation of single cell activity to active movements and somatosensory stimulation in the awake primate. Neurons (N = 707) were categorized on the basis of their relation to active movements or responses to sensory stimulation of individual body parts. 38% of neurons studied were related to the arm, 9% to the leg, 11% to the mouth or face, and 3% to axial portions of the body. The remaining neurons exhibited non-specific activation which could not be confidently localized to an individual body part (12%) or did not respond during the examination (26%). The high proportion of arm neurons was due to the focus of this study on cells related to arm movements. A large proportion (41%; N = 270) of the “arm” neurons was responsive to somatosensory stimulation. For these neurons the most effective stimulus (82%) was passive joint rotation. Six (5%) of the arm neurons responded to cutaneous stimulation. The putamen was found to be somatotopically organized. Neurons related to different body parts (leg, arm, and face) were segregated, and each body part was represented over a long anteroposterior extent of the nucleus. Clusters of 2–5 neurons with similar relations to active movements or responsive to passive movements of a single joint were often encountered over a 100–500 μ distance. Clusters of neurons with sensory driving were organized by joints. Rather than a single elbow or shoulder area, multiple clusters of neurons related to each joint were widely distributed over a long anteroposterior extent of the nucleus and were adjacent to clusters of neurons related to other joints of the arm. These clusters of neurons with similar functional properties may correspond to the subunits of the striatum which have been revealed by anatomic and morphologic studies. We propose that these clusters of neurons with similar functional properties represent the basic functional units of the striatum in a manner analogous to the functional columns of the neocortex.

366 citations


Journal ArticleDOI
24 May 1984-Nature
TL;DR: It is found that the auditory receptive fields shifted with changes in eye position, allowing the auditory and visual maps to remain in register, as well as other data suggesting that the primate SC is organized in motor, not sensory, coordinates.
Abstract: The process by which sensory signals are transformed into commands for the control of movement is poorly understood. A potential site for such a transformation is the superior colliculus (SC), which receives auditory, visual and somatosensory inputs1–3 and contains neurones that discharge before saccadic eye movements4–6. Along the primary sensory pathways, signals coding the spatial location of auditory, visual and somatosensory targets are based on distinctly different coordinate systems, and it is not known whether each type of sensory input uses a separate motor pathway or if they are converted into a common coordinate system in order to share a single pre-motor circuit. Sensory neurones in the SC have spatially restricted receptive fields (RFs) and are organized into maps across the collicular surface7–9. Acute experiments have shown a rough correspondence between the spatial positions of RFs of neurones encountered along a single dorsal–ventral penetration of the colliculus, regardless of the modality of the effective stimulus10–14, suggesting that auditory, visual and somatosensory maps might be in register. However, in these conditions the head-centred auditory system and the retinotopic visual system are aligned because the eyes are in the primary orbital position15. Moreover, other data have suggested16–18 that the primate SC is organized in motor, not sensory, coordinates, although in the cat, eye position was found to have no effect on auditory receptive fields19. We therefore sought here to determine what happens to the registration of the auditory and visual maps in the alert, behaving animal. Monkeys, with heads fixed, were trained to make delayed saccadic eye movements to auditory or visual targets from one of three initial fixation points while the activity of single neurones was recorded extracellularly. We found that the auditory receptive fields shifted with changes in eye position, allowing the auditory and visual maps to remain in register.

351 citations


Journal ArticleDOI
TL;DR: A differential effect of BMI is suggested, suggesting that GABA controls receptive-field size in rapidly adapting regions, and indicates that neurons in rapid adapting regions differ pharmacologically from those in other submodality regions.
Abstract: Extracellular recordings of 209 neurons were obtained with carbon fiber-containing multibarrel micropipettes. The cells were isolated in the primary somatosensory cortex of cats anesthetized with barbiturate and classified according to the nature of their response to natural stimuli, the nature of the surrounding multiunit responses to the same stimuli, the response to thalamic stimulation, and their depth in the cortex. To study factors controlling the excitability of somatosensory neurons, their receptive fields were examined in the presence of iontophoretically administered gamma-aminobutyric acid (GABA), glutamate, and bicuculline methiodide (BMI). Even when the neurons were depolarized to perithreshold levels with glutamate, or when local inhibitory influences mediated by GABA were antagonized by BMI, the apparent specificity for one class of afferent input was maintained. Neurons responding to stimulation of either cutaneous or deep receptors maintained their modality specificity, and neurons in cutaneous rapidly adapting regions never took on slowly adapting properties. When ejected at currents that did not elicit action potentials, glutamate lowered the threshold for activation by cutaneous stimuli but did not enlarge the receptive field. With larger ejecting currents, the neurons developed an on-going discharge, but even at these higher doses, glutamate did not produce an increase in the receptive-field size. Some neurons in regions of cortex exhibiting slowly adapting multiunit responses were relatively insensitive to glutamate. These cells required four to five times more glutamate to evoke discharges than did most neurons. Other cells, previously unresponsive to somatic stimuli, could be shown to possess distinct cutaneous receptive fields when either glutamate or BMI was ejected in their vicinity. Iontophoretically administered BMI altered the firing pattern of somatosensory neurons, causing them to discharge in bursts of 3-15 impulses. BMI enlarged the receptive-field size of neurons in regions displaying rapidly adapting multiunit background discharges but not in those regions with slowly adapting multiunit discharges. This differential effect of BMI, suggesting that GABA controls receptive-field size in rapidly adapting regions, also indicates that neurons in rapidly adapting regions differ pharmacologically from those in other submodality regions. In all cortical regions, BMI blocked the poststimulus inhibitory period that normally followed thalamic stimulation.(ABSTRACT TRUNCATED AT 400 WORDS)

349 citations


Journal ArticleDOI
TL;DR: It was 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, which are discussed in relation to the possible function of the postarcuates region of the premotor cortex in the sensory guidance of movement.
Abstract: 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.

291 citations


Journal ArticleDOI
TL;DR: The results suggest that age-related changes in human sensory systems are not uniform, but rather are different in specific portions of these systems, different at particular epochs of the life span, and stronger in males than in females.

220 citations


Journal ArticleDOI
TL;DR: Results are consistent with the suggestion that SII, but not area 5, is a critical station in a tactile processing pathway that proceeds from the primary somatosensory cortex (SI) to the limbic structures of the temporal lobe through links in SII and the insular cortex.

212 citations


Journal ArticleDOI
TL;DR: The findings suggest that cortical representations of deafferented skin can become activated by substitute cutaneous inputs, and suggests these changes are due to functional modifications in normally existing connections.
Abstract: The hindpaw of the rat is normally innervated by the sciatic and saphenous nerves. In the present studies, the hindpaws of adult rats were partially deafferented by transection of the sciatic nerve for variable periods of time. The organization of the hindpaw representation in primary somatosensory (S-I) cortex was then studied with neurophysiological mapping techniques and compared to the organization seen in normal rats. The objective was to determine whether cutaneous responsiveness was recovered in the cortical area which lost normal cutaneous inputs from the sciatic nerve, and, if recovery occurred, to characterize the time course and spatial extent of this recovery. Normal rats were found to have a topographically organized representation of the hindpaw in S-I cortex. As determined by nerve recording and cortical mapping, approximately 85% of this representation is responsive to cutaneous inputs from the sciatic nerve, while the remaining 15% is responsive to inputs from the saphenous nerve. Following transection of the sciatic nerve, all hindpaw skin regions normally innervated by the sciatic nerve remained denervated. In cortex, the representation of cutaneous inputs from the saphenous nerve expanded into parts of the hindpaw region normally representing sciatic inputs and occupied an area about 3 times larger than the saphenous representation in normal rats. This expansion was initially observed 1 to 2 days after transection and was stably maintained with longer deafferentation times. However, even after chronic deafferentation of up to 5 months, this enlarged saphenous representation was still only half the size of the normal hindpaw representation in normal rats. These findings suggest that cortical representations of deafferented skin can become activated by substitute cutaneous inputs. The rapid time course for substitution suggests these changes are due to functional modifications in normally existing connections. With the deafferentation conditions used in the present study, input substitution was limited to only parts of the deprived cortex. A hypothesis is presented which suggests these changes are due to adjustments in the dominance of saphenous and sciatic inputs to specific regions of cortex.

196 citations


Journal ArticleDOI
TL;DR: Recordings from the representations of the glabrous digits in area 3b of the somatosensory cortex of owl and macaque monkeys revealed two types of neurons, Rapidly adapting (RA) and Slowly adapting (SA), which suggested the existence of separate clusters or bands of SA and RA neurons in the middle layers of cortex.
Abstract: Recordings from the representations of the glabrous digits in area 3b of the somatosensory cortex of owl and macaque monkeys revealed two types of neurons Rapidly adapting (RA) neurons responded o

194 citations


Journal ArticleDOI
TL;DR: Data suggest that CPIA is a system which primarily regulates animals' responsiveness to external stimuli, in part by influencing segmentally organized behaviors.

174 citations


Journal ArticleDOI
TL;DR: It is provided evidence that callosal projections within the primary somatosensory cortex of the rat are distributed in a detailed pattern which is complementary to the pattern of specific thalamocortical projections to this cortical region.

145 citations


Journal ArticleDOI
TL;DR: In neonatally sectioned animals the number of myelinated fibres surviving in the peripheral nerve proximal to the lesion was 11% compared with 100% survival after adult nerve section, and in animals sectioned as adults no evidence of plasticity could be detected in the trigeminal nuclei.
Abstract: The infraorbital nerve was cut in either neonatal (on day 0) or adult (day 60) rats and the peripheral regeneration prevented. After 60 days either anatomical or electrophysiological techniques were used to study the peripheral nerve, trigeminal nucleus and somatosensory cortex. In neonatally sectioned animals the number of myelinated fibres surviving, at 60 days, in the peripheral nerve proximal to the lesion was 11% compared with 100% survival after adult nerve section. This reduction in surviving nerve fibres in neonatally lesioned animals was associated with a significant reduction in cross-sectional area of all trigeminal nuclei (principalis, oralis, interpolaris and caudalis) of 18-29%. No significant change in area was present in animals sectioned as adults. Neonatally lesioned animals also showed a reduction of approximately 20% in the number of cells visible in cross-sections of all trigeminal nuclei. Animals sectioned as neonates showed marked plasticity at all nuclei in the trigeminal complex as well as in the cortex. Deafferented cells responded to new peripheral receptive fields so that the somatotopic organization of these cells was modified. Such cells are referred to throughout as 'reactivated' cells. However, in animals sectioned as adults no evidence of plasticity could be detected in the trigeminal nuclei. Only very limited reactivation was apparent in the cortex, so that the majority of deafferented cells remained unresponsive at both sites. A detailed comparison was made of twenty-three reactivated cells and twenty-five normal cells from nucleus principalis of animals with nerve section on day 0. The reactivated cells commonly showed larger, more complex receptive fields, longer latencies and lower following frequencies, although stimulus thresholds were similar. Thus reactivated cells showed more convergence and poorer synaptic security than normal cells. However, stimulation of the contralateral thalamus produced similar responses from both groups of cells, suggesting that not all inputs to reactivated cells were modified. The time course of the reactivation of cells in nucleus caudalis from animals lesioned on day 0 was followed over 30 days. No acute effect, for up to 24 h, was detected. However, somatotopic reorganization had started by day 7, proceeded rapidly between days 7 and 14, and was completed by day 21.

Journal ArticleDOI
TL;DR: Somatosensory compensation for vestibular deficiency was demonstrated by stepping in circles in the dark as mentioned in this paper, which provides a complex pattern of afferent sigmoid signals, which in combination represent actual movement.
Abstract: Somatosensory compensation for vestibular deficiency was demonstrated by stepping in circles in the dark. Stepping around in small circles provides a complex pattern of afferent somatosensory signals, which in combination represent the actual movement. Labyrinth-less patients, i.e. patients devoid of labyrinthine function, reported during real as well as during apparent stepping around (on a rotating platform without stimulation of the canals) a strong sensation of rotation, as did the healthy subjects; they had a stronger somatosensory nystagmus than the healthy controls. In controls, the somatosensory and vestibular aftersensations cancelled, while the vestibular slightly outweighed their somatosensory afternystagmus. Labyrinthless subjects had no vestibulo-culomotor integrator function.

Journal ArticleDOI
TL;DR: A method is described which utilizes the recording of somatosensory evoked responses and cortical stimulation to localize the sensorimotor area under general anesthesia and the neurological results are discussed, demonstrating multiple and spatially separate, sensory and motor representations of the body in the somatoensory and motor gyri.
Abstract: A method is described which utilizes the recording of somatosensory evoked responses and cortical stimulation to localize the sensorimotor area under general anesthesia. It has been used in 31 patients who had lesions located in or near the somatosensory or motor gyri. Twenty-six of these patients had a tumor, and the remaining five had a tuberculoma, cysticercoid cyst, thrombosed arteriovenous malformation, cystic infarct, and astrocytic proliferation, respectively. Case histories of selected patients are briefly reported to demonstrate how the method can be used to improve the safety of surgical excisions in the sensorimotor area. The neurological results are discussed in relation to recent physiological studies, demonstrating multiple and spatially separate, sensory and motor representations of the body in the somatosensory and motor gyri.

Journal ArticleDOI
TL;DR: The complex relationships between the type of SEP abnormalities and the location of cerebral lesions can best be explained by postulating the presence of multiple, at least partially independent, thalamocortical projections mediating regionally specific somatosensory inputs.

Journal ArticleDOI
01 Jan 1984
TL;DR: The data indicate that neonatal damage to the whiskers alters both the anatomical arrangement of the barrels and the physiologically determined somatotopic representation of the sensory periphery in a parallel and predictable fashion.
Abstract: This study was undertaken to determine the functional properties of neurons in the anatomically altered somatosensory cortex after neonatal whisker damage. In mice and rats neonatal lesions of the facial vibrissae change the anatomical organization of barrels in the contralateral SmI cortex. These changes depend on the pattern and severity of the peripheral damage and the developmental age of the animals. To understand some of the functional correlates of these anatomical changes, the middle row of vibrissae (row C) was damaged in mice on postnatal days 1, 3, and 5 and in rats on postnatal days 1 and 5. The receptive field properties of single cortical units were studied after the animals matured. In 24 mice and 15 rats a total of 1,370 units were characterized in microelectrode penetrations which passed through the somatosensory cortex either tangential or perpendicular to the pia. Units were localized anatomically with respect to both barrel and laminar boundaries, and the extent of the peripheral damag...

Journal ArticleDOI
TL;DR: The retrograde transport of horseradish peroxidase (HRP) was combined with extracellular microelectrode recording from single and multiple-neurones to study the anatomical and functional organization of the callosal connections of the hand sensory projection field in the parietal operculum of monkeys.

Journal ArticleDOI
TL;DR: The organization of somatosensory projections to the dysgranular areas of somatic sensory cortex was mapped in albino rats and receptive fields that activate layer IV granule cells in these Dysgranular zones were cutaneous and deep, roughly somatotopic, larger, and required stronger stimulation than the cutaneous light touch RFs of the adjacent granule cell zones.

Journal ArticleDOI
TL;DR: Cortical somatosensory evoked potentials to posterior tibial nerve stimulation were obtained in 29 normal controls varying in age and body height and showed marked interindividual variability and have very limited value in defining abnormality.

Journal ArticleDOI
TL;DR: Evidence of a sensory role of the cerebellum, mediating a modulation of effectiveness of afferent input at other parts of the brain, has been reported previously for certain sense modalities but has not been evaluated across several in a mammal.
Abstract: Evidence of a sensory role of the cerebellum, mediating a modulation of effectiveness of afferent input at other parts of the brain, has been reported previously for certain sense modalities but has not been evaluated across several in a mammal. After a conditioning train of stimuli applied to the cerebellar surface in unanesthetized rats, diffuse flashes, acoustic clicks, and shocks to the sciatic nerve evoked multiunit and field potential responses that were recorded at three levels: midbrain, thalamus, and cerebral cortex. At a best interval between end of conditioning train (cerebellar) and test (sensory) stimuli, all three levels show modulation of the evoked responses, each in a specific direction (enhancement or depression), with a characteristic time course. Visual responses in the tectum are enhanced; those in the cortex are depressed. Tectal responses that have been nearly abolished by increasing background illumination are partially restored by the conditioning cerebellar train. Auditory brainstem responses (short latency, less than 10 ms, far-field waves I to III, attributed to medullary levels) are depressed; wave IV from the inferior colliculus is relatively enhanced at short intervals and is depressed at longer intervals. Somatosensory responses in thalamus and cortex are depressed. Lobulae V, VI, and VII of the vermis are more effective sites of stimulation than other areas tested. Most of the modulations are ascribed to central sites; a few are ascribed to peripheral sites.

Journal ArticleDOI
TL;DR: A pathological slowing of conduction along the central sensory pathways in amyotrophic lateral sclerosis is suggested.
Abstract: Forty five patients with amyotrophic lateral sclerosis were investigated, by means of somatosensory evoked potentials, in order to detect the presence of subclinical sensory changes. Cervical SEPs from the median nerve and cortical SEPs from the median and tibial nerve were recorded, showing a delay of N13 and subsequent components; the latency of the first constant cortical potential was also increased in many patients. Only the SEPs from the tibial nerve showed a decrease of amplitude. These results suggest a pathological slowing of conduction along the central sensory pathways in amyotrophic lateral sclerosis.

BookDOI
01 Jan 1984
TL;DR: The Cerebellum as a Neuronal Machine, the Sensorimotor Integration in an Insect's Brain, and the Neurophysiological Basis for the Flashing Dialog in the Firefly Luciola lusitanica are reviewed.
Abstract: Curriculum Vitae and Bibliography of Sir John Eccles.- I. The Self and Its Brain.- Critical Remarks on the Knowledge of Lower and Higher Organisms, the So-Called Sensory Motor Systems.- Impasses and Fallacies of the Brain-Mind Discussion.- II. Reflex Activity of the Spinal Cord.- Non-invasive Analysis of the Spinal Cord Generators Activated by Somatosensory Input in Man: Near Field and Far Field Potentials.- Organization of Reflexes Evoked by Stimulation of Neck Receptors.- On Neuronal Pathways of Presynaptic Depolarization of Group I Muscle Afferents.- Spinal Integration of the Command for Respiratory Movements.- Segmental Control of Pain.- Central Effects by Ventral Root Nociceptive Afferents.- III. The Cerebellum as a Neuronal Machine.- Purkinje Cells of the Cerebellum: Localization and Function of Multiple Neuroactive Substances.- Integration of Mossy Fiber and Climbing Fiber Inputs to Purkinje Cells.- Cerebrocerebellar Interactions in Premovement Organization of Conditioned Hand Movements in the Monkey.- Cerebellar Plasticity and Motor Learning.- The Cerebellum and Adaptive Tuning of Movements.- Recent Aspects of the Function of the Inferior Olive.- IV. The Physiology of Nerve Cells.- What Central Inhibitory Pathways Tell Us About Mechanisms of Transmitter Release.- Reorganization of Neuronal Membrane Properties Following Axotomy.- Posttetanic Potentiation, Presynaptic Inhibition, and the Modulation of the Free Ca2+ Level in the Presynaptic Terminals.- Mechanosensibility of Joint Receptors with Fine Afferent Fibers.- V. The Physiology of Synapses.- The Form and Function of Synapses.- Norepinephrine and Acetylcholine Block a Calcium-Activated Potassium Hyperpolarization in Hippocampal Pyramidal Cells.- Evidence for Both Pre- and Postsynaptic Mechanisms During Long-Term Potentiation in Hippocampal Slices.- Long-Term Potentiation and Inhibition in CA3 Neurons.- Synaptic Plasticity in the Red Nucleus.- VI. The Understanding of the Brain.- Neocortical Neuron Circuit Models Reconsidered in the Light of the New Techniques.- The Sensorimotor Integration in Area 3a of the Cat.- Neuronal Organization of Cat Motor Cortex.- The Supplementary Motor Area in the Light of Recent Investigations.- Sensorimotor Integration in an Insect's Brain: The Neurophysiological Basis for the Flashing Dialog in the Firefly Luciola lusitanica (Charp.).- VII. The Neurophysiological Basis of Mind.- Anomalous Contours: A Tool in Studying the Neurophysiology of Vision.- Attention, Readiness for Action, and the Stages of Voluntary Decision - Some Electrophysiological Correlates in Man.- Electrophysiological Cues of the Language-Dominant Hemisphere in Man: Slow Brain Potentials During Language Processing and Writing.

Journal ArticleDOI
TL;DR: It is suggested that the motor function of the somatosensory cortex becomes predominant and compensates for dysfunction of the motor cortex when it is temporarily impaired.
Abstract: The motor cortex was temporarily impaired by local cooling during repeated execution of visually initiated hand movements in monkeys. The effects of cooling were examined by recording premovement cortical field potentials in the forelimb motor and somatosensory cortices and by measuring reaction time and force exerted by the movement. The cortex was cooled by perfusing cold water (about 1° C) through a metal chamber placed on the cortical epidural surface. Cooling of the forelimb motor area lowered temperature of the cortex under the chamber to 20–29° C within 4–5 min. Recording electrodes for cortical field potentials were implanted chronically on the surface and at 2.5–3.0 mm depth of various cortical areas including that being cooled. Spread of cooling to surrounding cortical areas was prevented by placing chambers perfused with warm water (38–39° C) on the areas. Cooling of the forelimb motor area greatly reduced its premovement cortical field potentials, followed by prolonged reaction times of weakened contralateral wrist muscles. Simultaneous recording from the primary somatosensory cortex revealed an enhancement of its premovement field potentials. All changes were completely reversible by rewarming of the motor cortex. Concomitant cooling of the motor and somatosensory cortices entirely paralysed the contralateral wrist muscles. These results suggest that the motor function of the somatosensory cortex becomes predominant and compensates for dysfunction of the motor cortex when it is temporarily impaired.

Journal ArticleDOI
TL;DR: The present study demonstrated that substantial direct somatosensory cortical influences on the superior colliculus (SC) originate from three areas: a) SIV, b) para-SIV (the cortex adjacent to SIV but deeper in the anterior ectosylvian sulcus (AES) and for which no topography has yet been described), and c) the rostral suprasylvIAN sulcus.
Abstract: Using electrophysiological techniques, the present study demonstrated that substantial direct somatosensory cortical influences on the superior colliculus (SC) originate from three areas: a) SIV, b) para-SIV (the cortex adjacent to SIV but deeper in the anterior ectosylvian sulcus (AES) and for which no topography has yet been described), and c) the rostral suprasylvian sulcus. Influences also appeared to originate from SI and SII, but these may have been indirect. Detailed examination of the AES revealed that these corticotectal projections are topographically organized, and stimulation of a given cortical locus was observed to affect only those cells in the SC whose receptive fields overlapped those of cells at the stimulation site. A similar receptive-field register was found between the suprasylvian sulcus and the SC. Within this topographic pattern, considerable convergence was evident and an individual SC cell could be influenced from a surprisingly large cortical area. This was particularly evident within the representation of the forelimb. Thus, an SC cell with a receptive field covering the forelimb and paw could receive convergent input from many cortical cells with receptive fields covering all or restricted portions of this body region. Considerable corticotectal divergence also was observed within this general topographic scheme. For example, a given corticotectal site representing the digits sent projections to many different SC cells that included the digits within their receptive fields. These data are more consistent with a block-to-block than a point-to-point corticotectal projection. Somatosensory corticotectal projections excited only those SC cells that could also be activated by peripheral somatosensory stimuli. Similarly, the caudal AES, which contains auditory cells, excited only those SC cells activated also by peripheral auditory stimuli. Yet convergent influences from both auditory and somatosensory regions of the AES were observed in the SC cells that could be activated by both auditory and somatosensory stimuli. These data indicate that the AES is a major source of excitatory input to cells of the deep laminae of the SC. Since it is these deep laminae cells that project to premotor regions of the brain stem and the spinal cord, it is reasonable to suppose that the AES has a significant impact on the output signals of the SC that initiate the orientation responses to peripheral sensory stimulation.

Journal ArticleDOI
TL;DR: The present study suggests the compensatory motor function of the somatosensory cortex for the dysfunction of the motor cortex in early weeks after cerebellar hemispherectomy.
Abstract: Electrical activities of the motor and somatosensory cortices preceding visually-initiated hand movements were recorded with electrodes chronically implanted on the surface and at 2.5–3.0 mm depth in the cortex of monkeys, and changes in field potentials in these cortices after cerebellar hemispherectomy were observed for many weeks. As previously reported, a unilateral cerebellar hemispherectomy including the lateral and interpositus nuclei eliminates the cerebellar-mediated superficial thalamo-cortical (T-C) responses recorded in the forelimb motor cortex contralateral to the hemispherectomy. These T-C responses normally precede the hand movement, and the operation results in the delay of movement initiation. The electrodes in the forelimb area of the contralateral primary somatosensory cortex showed an enhancement of superficial T-C responses of the somatosensory cortex for 30–40 days after the operation. The enhanced potentials preceded the delayed movement as do the cerebellar-mediated superficial T-C responses of the motor cortex in normal situations. Local cooling of the somatosensory cortex following the cerebellar hemispherectomy disturbed the reaction time movement for a few weeks after the operation. This effect was rarely encountered in normal monkeys. The present study suggests the compensatory motor function of the somatosensory cortex for the dysfunction of the motor cortex in early weeks after cerebellar hemispherectomy.

Journal Article
TL;DR: Physiological evidence, including some recent microneurographic data obtained in man, that suggests the existence of a sympathetic influence on somatosensory input is reviewed and abnormal sympathetic-afferent connections might occur following nerve injury.
Abstract: Physiological evidence, including some recent microneurographic data obtained in man, that suggests the existence of a sympathetic influence on somatosensory input is reviewed Following nerve injury abnormal sympathetic-afferent connections might occur Hypothetically, such abnormalities could be of significance in clinical states involving nerve injuries where sensory and trophic dysfunctions are also prominent characteristics

Journal ArticleDOI
TL;DR: These findings support the view that responses of many somatosensory cortical neurons are modulated by central as well as peripheral influences and are dependent upon the context in which the stimulus occurs.

Journal ArticleDOI
TL;DR: In the catfish, different sensory modalities are represented by discrete, only partly overlapping areas of the cerebellum, with findings of modality segregation and features of interest for comparative neurology.

Journal ArticleDOI
TL;DR: Constant latencies at different spinal levels and comparison with the latency of the ascending volley indicate that the complex was not derived from the spinal cord but from more rostral structures, and therefore only transit time, rather than velocity, could be measured.

Journal ArticleDOI
TL;DR: In urethane‐anesthetized rats a 0.36‐mm metallic cannula for infusion was positioned in the somatosensory component of the thalamic reticualar nucleus, where movement of the vibrissae evoked neuronal discharge, and excitation of neurons in sTR inhibits those in VB, but the effect appears to be highly coordinated somatotopically.
Abstract: In urethane-anesthetized rats a 0.36-mm metallic cannula for infusion was positioned in the somatosensory component of the thalamic reticular nucleus (sTR), where movement of the vibrissae evoked neuronal discharge. Infusion there of 0.125-0.5 microliter of a 50 mM solution of glutamate over a 1-min period suppressed both spontaneous and evoked discharge of neurons in the ventrobasal complex (VB), but only for those which also responded to vibrissal stimulation. VB neurons activated by somatosensory stimuli at other locations were unaffected. Thus, excitation of neurons in sTR inhibits those in VB, but the effect appears to be highly coordinated somatotopically.

Journal ArticleDOI
TL;DR: A profound change in the responses of intralaminar neurons in arthritic rats, as compared with those observed in normal animals is revealed.