Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Sensorimotor Cortex”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 775 records · Page 43Linked to original sources
PubMed1998

Multiple subpial transection in patients with extratemporal epilepsy.

Multiple subpial transection (MST) was developed to permit the treatment of partial epilepsies that reside in or encroach on eloquent cortex (language and sensorimotor cortex). It was conceived after the discoveries of the columnar organization of neocortex and that expression and spread of seizures utilize the transverse fiber network. Although the technique is simple in principle, it takes a skilled and practiced hand to avoid damage to the neocortical columns and vascular supply. The efficacy in controlling seizures with MST in extratemporal epilepsy is similar to that of resective surgery. Activities of daily living are not adversely impacted by MST. MST is a viable alternative to resection in extratemporal epilepsy.

Activities of Daily Living↗
PubMed2006

Switching of sensorimotor transformations: antisaccades and parietal cortex.

The sensorimotor processing necessary in complex realistic situations goes beyond straight-forward application of a given sensorimotor transformation. Contextual information may make it necessary to switch to another sensorimotor transformation. We studied the issue of switching by using the mixed memory prosaccade/antisaccade task. Neurons of the lateral intra-parietal area (LIP) might be involved in computing the sensorimotor transformations for both prosaccades and antisaccades. LIP neurons may also be involved in switching to the antisaccade sensorimotor transformation, when an antisaccade is requested. Some neurons in LIP show a paradoxical pattern of activity-motor in space but visual in time. Funahashi, Chafee and Goldman-Rakic reported in 1993 a complimentary pattern of activity in prefrontal cortex-visual in space but motor in time. These odd observations are explained by the hypothesis that (1) the parietal cortex contains a sensorimotor transformation module, and prefrontal cortex a context categorization module, and (2) following target onset, information flows from early visual system to parietal cortex and on to prefrontal cortex; then, a second wave of activation, contingent on a switching signal, arrives back at parietal cortex. The duration of this loop is less than 100 ms. Thus, the paradoxical activities are intermediate representations derived in the cognitive processing involved in switching sensorimotor transformations.

Animals↗
PubMed1991

Cortical somatosensory evoked potentials. II. Effects of excision of somatosensory or motor cortex in humans and monkeys.

1. To clarify the generators of human short-latency somatosensory evoked potentials (SEPs) thought to arise in sensorimotor cortex, we studied the effects on SEPs of surgical excision of somatosensory or motor cortex in humans and monkeys. 2. Normal median nerve SEPs (P20-N30, N20-P30, and P25-N35) were recorded from the cortical surface of a patient (G13) undergoing a cortical excision for relief of focal seizures. All SEPs were abolished both acutely and chronically after excision of the hand area of somatosensory cortex. Similarly, excision of the hand area of somatosensory cortex abolished corresponding SEPs (P10-N20, N10-P20, and P12-N25) in monkeys. Excision of the crown of monkey somatosensory cortex abolished P12-N25 while leaving P10-N20 and N10-P20 relatively unaffected. 3. After excision of the hand area of motor cortex, all SEPs were present when recorded from the cortical surface of a patient (W1) undergoing a cortical excision for relief of focal seizures. Similarly, all SEPs were present in monkeys after excision of the hand area of motor cortex. 4. Although all SEPs were present after excision of motor cortex in monkeys, variable changes were observed in SEPs after the excisions. However, these changes were not larger than the changes observed after excision of parietal cortex posterior to somatosensory cortex. We concluded that the changes were not specific to motor cortex excision. 5. These results support two major conclusions. 1) Median nerve SEPs recorded from sensorimotor cortex are produced by generators in two adjacent regions of somatosensory cortex: a tangentially oriented generator in area 3b, which produces P20-N30 (human) and P10-N20 (monkey) [recorded anterior to the central sulcus (CS)] and N20-P30 (human) and N10-P20 (monkey) posterior to the CS; and a radially oriented generator in area 1, which produces P25-N35 (human) and P12-N25 (monkey) recorded from the postcentral gyrus near the CS. 2) Motor cortex makes little or no contribution to these potentials.

Adolescent↗
PubMed1992

[Connections of the posterior region of the thalamus in rats].

Using retrograde and anterograde tracing methods we have studied in the posterior region of the thalamus of the rat the distribution of: (1) the terminal fields of the main afferents arising from somatosensory centers (dorsal column nuclei, interpolar trigeminal subnucleus, somatosensory cortex), motor centers (red nucleus, motor cortex) and multimodal structures (deep layers of the superior colliculus, zona incerta, cingular cortex) and of (2) the neurons giving rise to the main efferents towards the sensorimotor cortex, the red nucleus, the deep layers of the superior colliculus and the zone incerta. The overlap of the retrograde and anterograde labeling reveals a relatively homogeneous region. Considering however the cortical connections, three different subdivisions can be distinguished: a caudal pole completely devoid of cortical connections, a medial subdivision receiving cortical afferents from the sensorimotor and cingulate cortices and a rostral pole reciprocally connected with the sensorimotor cortex. Therefore the rostral pole would be the only part of this region which should be included in the thalamus.

Afferent Pathways↗
PubMed2005

Modulation of motor cortex excitability by sustained peripheral stimulation: the interaction between the motor cortex and the cerebellum.

The excitability of cortical neurons in the motor cortex is determined by their membrane potential and by the level of intracortical inhibition. The excitability of the motor cortex as a whole is a function of single cell excitability, synaptic strength, and the balance between excitatory cells and inhibitory cells. It is now established that a sustained period of somatosensory stimulation increases the excitability of motor cortex areas controlling muscles in those body parts that received the stimulation prior to excitability testing. So far, it has been supposed that the sensorimotor cortex was the anatomical substrate of these excitability changes, which could represent an early change in cortical network function before structural plasticity occurs. Recent experimental studies highlight that the cerebellum, especially the interpositus nucleus, plays a key role in the adaptation of the motor cortex to repeated trains of stimulation. Interpositus neurons, which receive inputs from both sensorimotor cortex and the spinal cord, are involved in somesthetic reflex behaviors and assist the cerebral cortex in transforming sensory signals to motor-oriented commands by acting via the cerebello-thalamo-cortical projections. Moreover, climbing fibers originating in the inferior olivary complex and innervating the nucleus interpositus mediate highly integrated sensorimotor information derived from spinal modules. It appears that the interpositus nucleus is a main subcortical modulator of the excitability changes occurring in the motor cortex, which may be a substrate of early plasticity effective in motor learning and recovery from lesion.

Afferent Pathways↗
PubMed1987

[Localization of sources of thalamic inputs into the sensomotor area of the cerebral cortex of the rabbit using the technic of retrograde axonal transport of horseradish peroxidase].

A horseradish peroxidase study has shown that the rabbit sensorimotor cortex received afferent fibres from the neurons, located in specific, nonspecific and associative thalamic nuclei. The location, form and size of the somata of relay cells were analyzed in these nuclei. The total number of cells of the origin of thalamo-sensorimotor-cortical fibres was calculated and the coordinates of the loci with maximal density were determined. Among the relay cells the most abundant ones appeared to be multipolar neurons (12-20 micron in size) and stellate cells (10-15 micron). Among the specific nuclei most of afferent fibres originated from n. ventralis lateralis, n. ventralis anterior and n. anterior ventralis; a comparable number of fibres originated from n. medialis dorsalis and n. paracentralis that had much more labelled cells than other associative and nonspecific nuclei, respectively. It is supposed that the afferentation from many thalamic nuclei is essential for the sensorimotor cortex to participate in thalamocortical interactions.

Afferent Pathways↗
PubMed1989

Role of the parietal cortex for sensorimotor transformation. Evidence from clinical observations.

Somatosensory and motor functions of both hands were examined in 10 patients with unilateral parietal cortex lesions as revealed by computerized tomography. Tests of elementary somatosensory functions comprised surface sensibility, vibration, and position sense. For evaluation of complex somatosensory functions, the recognition of surface textures and object forms was tested. Motor performance was examined by measuring force and position control as well as manipulative and explorative motor behaviour. All patients showed varying degrees of sensory disturbance. Although the patients had no or minor paresis, they all had motor deficits concerning force control, fine movements, and manipulation with the hand contralateral to the lesion. Patients with more posteriorly located parietal lesions revealed predominantly severe disturbances of complex sensibility, precision grip, manipulation, and explorative finger movements. The characteristic and consistent feature of the disturbed motor behaviour was the loss of the purposive nature of the motor acts which were no longer adequate for the tasks (tactile apraxia). Paresis or ataxia could not account for this deficits.

Afferent Pathways↗
PubMed1983

In vivo release from cerebral cortex of [14C]glutamate synthesized from [U-14C]glutamine.

Awake, unrestrained, and behaviourally normal animals with superfusion cannulae implanted over the sensorimotor cortex were used in a study of the capacity of infused [U-14C]glutamine for labelling glutamate and other amino acids released by depolarising stimuli. A spontaneous background release of [14C]glutamate was detected. This was increased by tityustoxin (1 microM). The specific radioactivity of glutamate increased eightfold during the evoked-release period. [14C]Aspartate was also detected and showed increased release, but not increased specific labelling, in response to depolarisation. Evoked gamma-aminobutyric acid (GABA) release occurred but only small amounts of [14C]GABA were detected. Glutamine showed increased rates of uptake to the sensorimotor cortex during stimulation periods, suggesting an accelerated breakdown via glutaminase.

Animals↗
PubMed2002

Retrograde repression of growth-associated protein-43 mRNA expression in rat cortical neurons.

Corticospinal neurons support rapid growth of axons toward spinal cord targets in the perinatal period. Initial axon growth is accompanied by elevated expression of growth-associated protein-43 (GAP-43), which then declines in postnatal development. To investigate whether expression of GAP-43 mRNA is regulated by retrograde signals, we injected colchicine into the corticospinal tract to block retrograde axonal transport during a time when GAP-43 is normally declining in corticospinal neurons. Colchicine caused a prolongation of high GAP-43 mRNA expression in neurons located in layer V (but not other layers) of sensorimotor cortex. We next used osmotic minipumps to infuse soluble adult spinal cord extract into the sensorimotor cortex. This resulted in a premature downregulation of GAP-43 mRNA in identified corticospinal neurons. GAP-43 repressive activity was found in extracts of the spinal cord tissue as young as postnatal day 8. The effect of spinal cord extract in vivo was not mimicked by adult cerebellar or muscle extracts. Cultures of postnatal cortical neurons also underwent downregulation of GAP-43 mRNA when treated with spinal cord extract. Activation of cAMP signaling also repressed GAP-43 mRNA in cortical cultures, and the repressive effect of spinal cord extract was diminished by an adenyl cyclase inhibitor. Thus, GAP-43 mRNA may be downregulated late in development by a target-derived retrograde repressive factor, and this effect may be mediated by cAMP second messenger signaling.

Animals↗
PubMedDate not supplied

[The neuronal organization of a focus of conditioned excitation in the cat sensory-motor cortex].

The activity of single units in the focus of conditioned excitation was studied during defensive conditioning to direct electrical stimulation of the cat sensorimotor cortex. Reorganizations of spike activity set in during the period of reflex elaboration, were manifest in the increased number of excited neurones and those which respond both to the conditioned and unconditioned stimuli. In the course of elaboration, the inhibitory phase of unit responses to direct electrical stimulation of the sensorimotor cortex was reduced, while the frequency of background unit spike activity was enhanced. Acute extinction of the reflex restored the initial duration of the inhibitory phase and reduced the frequency of the background activity.

Animals↗
PubMed2005

Brain activation of lower extremity movement in chronically impaired stroke survivors.

Lower extremity paresis poses significant disability to chronic stroke survivors. Unlike for the upper extremity, cortical adaptations in networks controlling the paretic leg have not been characterized after stroke. Here, the hypotheses are that brain activation associated with unilateral knee movement in chronic stroke survivors is abnormal, depends on lesion location, and is related to walking ability. Functional magnetic resonance imaging of unilateral knee movement was obtained in 31 patients 26.9 months (mean, IQ range: 11.3-68.1) after stroke and in 10 age-matched healthy controls. Strokes were stratified according to lesion location. Locomotor disability (30 ft walking speed) did not differ between patient groups (9 cortical, 12 subcortical, 10 brainstem lesions). Significant differences in brain activation as measured by voxel counts in 10 regions of interest were found between controls and patients with brainstem (P = 0.006) and cortical strokes (P = 0.002), and between subcortical and cortical patients (P = 0.026). Statistical parametric mapping of data per group revealed similar activation patterns in subcortical patients and controls with recruitment of contralateral primary motor cortex (M1), supplementary motor area (SMA), and bilateral somatosensory area 2 (S2). Cortical recruitment was reduced in brainstem and cortical stroke. Better walking was associated with lesser contralateral sensorimotor cortex activation in brainstem, but stronger recruitment of ipsilateral sensorimotor and bilateral somatosensory cortices in subcortical and cortical patients, respectively. A post hoc comparison of brainstem patients with and without mirror movements (50%) revealed lesser recruitment of ipsilateral cerebellum in the latter. Subcortical patients with mirror movements (58%) showed lesser bilateral sensorimotor cortex activation. No cortical patient had mirror movements. The data reveal adaptations in networks controlling unilateral paretic knee movement in chronic stroke survivors. These adaptations depend on lesion location and seem to have functional relevance for locomotion.

Aged↗
PubMed2006

Plasticity of the motor cortex in Parkinson's disease patients on and off therapy.

We used the paired associative stimulation (PAS) technique to investigate associative plasticity of the sensorimotor cortex in 16 Parkinson's disease (PD) patients off and on therapy and in 10 age-matched controls. After PAS, motor evoked potential (MEP) amplitudes increased more and the cortical silent period showed a reduced prolongation in patients off therapy than in controls. These changes lasted for at least 30 minutes. In addition, MEP amplitudes increased in a less focal manner in patients off therapy than in controls. After patients received dopaminergic therapy, these abnormalities normalized. The abnormal responsiveness of sensorimotor cortex neurons to PAS in PD patients off therapy probably reflects disordered plasticity within the motor cortex.

Adult↗
PubMed1999

Quantitation of regional cerebral blood flow increases during motor activation: A multislice, steady-state, arterial spin tagging study.

Steady-state arterial spin tagging approaches were used to construct multislice images of relative cerebral blood flow changes during finger-tapping tasks. Statistically significant increases in cerebral blood flow were observed in primary sensorimotor cortex in all seven subjects. The mean volume of the activated region in the contralateral primary sensorimotor cortex was 0.9 cm(3), and the mean increase in cerebral blood flow in the activated area was 54% +/- 11%. Although the extended spatial coverage is advantageous for activation studies, the intrinsic sensitivity of the multislice approach is smaller than the intrinsic sensitivity of the single-slice, arterial spin tagging approach. Magn Reson Med 42:404-407, 1999. Published 1999 Wiley-Liss, Inc.

Cerebral Arteries↗
PubMed1999

Activity-dependent development of cortical axon terminations in the spinal cord and brain stem.

Corticospinal (CS) axon terminations in several species are widespread early in development but are subsequently refined into a spatially more restricted distribution. We studied the role of neural activity in sensorimotor cortex in shaping postnatal development of CS terminations in cats. We continuously infused muscimol unilaterally into sensorimotor cortex to silence neurons during the postnatal CS refinement period (weeks 3-7). Using anterograde transport of WGA-HRP, we examined the laterality of terminations from the muscimol-infused (i.e., silenced) and active sides in the spinal cord, as well as in the cuneate nucleus and red nucleus. We found that CS terminations from the muscimol-infused cortex were very sparse and limited to the contralateral side, while those from the active cortex maintained an immature bilateral topography. Controls (saline infusion, noninfusion) had dense, predominantly contralateral, CS terminations. There was a substantial decrease in the spinal gray matter area occupied by terminations from the side receiving the blockade and a concomitant increase in the area occupied by ipsilateral terminations from the active cortex. Optical density measurements of HRP reaction product from the active cortex in muscimol-infused animals showed substantial increases over controls in the ratio of ipsilateral to contralateral CS terminations for all laminae examined (IV-V, VI, VII). Our findings suggest that ipsilateral dorsal horn terminations reflect new axon growth during the refinement period because they are not present there earlier in development. Those in the ventral horn are present earlier in development and thus could reflect maintenance of transient terminations. Increased ipsilateral terminations from active cortex were due to recrossing of CS axons in lamina X and not to an increase in labeled CS axons in the ipsilateral white matter. Examination of brain stem terminations suggested that, between postnatal weeks 3 and 7, development of corticocuneate terminations also is activity-dependent but that development of corticorubral terminations is not. Activity-dependent CS development is a plausible mechanism by which early motor experiences could shape the anatomical and functional organization of the motor systems during a critical postnatal period.

Aging↗
PubMed2006

Cotransplant of neural stem cells and NT-3 gene modified Schwann cells promote the recovery of transected spinal cord injury.

STUDY DESIGN: An animal model of transected spinal cord injury (SCI) was used to test the hypothesis that cografted neural stem cells (NSCs) and NT-3-SCs promote morphologic and functional recoveries of injured spinal cord. OBJECTIVE: To explore whether cotransplant of NSCs and NT-3-SCs could promote the injured spinal cord repair. SETTING: Zhongshan Medical College, Sun Yat-sen University, PR China. METHODS: Female Sprague-Dawley (SD) rats weighing on 200-220 g were used to prepare SCI models. The spinal cord was transected between T(9) and T(10), then NSCs, SCs+NSCs, LacZ-SCs+NSCs, or NT-3-SCs+NSCs were grafted into the transected site. RESULTS: (1) Part of NSCs could differentiate to neuron-like cells in the transected site and the percentage of differentiation was NT-3-SCs+NSCs group>SCs+NSCs group>NSCs group. (2) In the grafted groups, there were 5-HT, CGRP, and SP positive nerve fibres within the transected site. Some fluorogold (FG)-labeled cells were found in the spinal cord rostral to the transected site, the red nuclei and the inner pyramidal layer of sensorimotor cortex. (3) The cells grafted could enhance the injured neurons survival in inner pyramidal layer of sensorimotor cortex, red nuclei of midbrain, and Clark's nuclei of spinal cord's L1 segment, could decrease the latency and increase the amplitude of cortical somatosensory evoked potential (CSEP) and cortical motor evoked potential (CMEP), and could promote partly structural and functional recovery of the SCI rats. CONCLUSION: These results demonstrate that cografted NT-3-SCs and NSCs is a potential therapy for SCI. SPONSORSHIP: This research was supported by Chinese National Key Project for Basic Research (G1999054009), Chinese National Natural Science Foundation (30270700) and Social Developmental Foundation of Guangdong Province (2003C33808) to YS Zeng; Natural Science Foundation of Guangdong Province (04300468) and Medical Science Research Grant of Guangdong Province (A2004081) to JS Guo.

Animals↗
PubMed2001

Combined functional magnetic resonance imaging and transcranial magnetic stimulation evidence of ipsilateral motor pathway with congenital brain disorder: a case report.

We present the case of 28-year-old man with schizencephaly who had mild left hemiparesis with mirror movement. Brain mapping using functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) for both hand muscles was done to evaluate his neurologic state. Motor evoked potential (MEP) from both abductor pollicis brevis (APB) muscles was obtained simultaneously. fMRI showed that the left primary sensorimotor cortex became active when the right fingers performed the flexion-extension exercise. The left primary sensorimotor cortex, left prefrontal area, and both supplementary motor areas were activated with flexion-extension exercise of the left hand. Brain mapping for both APB muscles using TMS showed that no MEP was evoked in the right hemisphere, but a APB total of 5 sites were evoked in the left hemisphere simultaneously. The optimal scalp site for both APB muscles was present at the same site. The MEPs of both muscles which were evoked by stimulation of the optimal scalp site, showed similar latencies, amplitudes, and figures of potential. The similarities in both MEPs and the same optimal scalp site support the assumption that MEPs of both APB muscles are produced by the corticospinal tract originating from the same motor cortex. Our results showed that the ipsilateral motor pathway extended from the unaffected left hemisphere to both hand muscles. This finding may reflect functional reorganization of motor area in a patient with congenital brain disorder.

Adult↗
PubMed1976

Electrophysiological investigations on the projections from the cerebral cortex to the vermal posterior lobe of the cerebellum.

The following cerebrocortical areas have been electrically stimulated in cats under Nembutal anaesthesia: forelimb and hindlimb areas of the primary sensorimotor cortex, primary and secondary acoustic areas and visual area. Stimulation of these regions evokes in the vermal portion of lobuli VI and VII of the cerebellum potentials at a short latency (2.8-3.5 ms) and at a longer latency (12-22 ms), which have been identified as due to mossy and climbing fibre inputs respectively. Each point of the cerebellar cortex receives usually projections by some and never by all the stimulated cerebrocortical areas. The different cortical regions don't project predominantly to separate parts of the cerebellar cortex, but they project in an apparently random manner with a patchy arrangement. In the anterior lobe we have confirmed the known somatotopy from the primary sensorimotor cortex and we have found no projections from the other cerebrocortical areas.

Animals↗
PubMed2006

Classification of fMRI independent components using IC-fingerprints and support vector machine classifiers.

We present a general method for the classification of independent components (ICs) extracted from functional MRI (fMRI) data sets. The method consists of two steps. In the first step, each fMRI-IC is associated with an IC-fingerprint, i.e., a representation of the component in a multidimensional space of parameters. These parameters are post hoc estimates of global properties of the ICs and are largely independent of a specific experimental design and stimulus timing. In the second step a machine learning algorithm automatically separates the IC-fingerprints into six general classes after preliminary training performed on a small subset of expert-labeled components. We illustrate this approach in a multisubject fMRI study employing visual structure-from-motion stimuli encoding faces and control random shapes. We show that: (1) IC-fingerprints are a valuable tool for the inspection, characterization and selection of fMRI-ICs and (2) automatic classifications of fMRI-ICs in new subjects present a high correspondence with those obtained by expert visual inspection of the components. Importantly, our classification procedure highlights several neurophysiologically interesting processes. The most intriguing of which is reflected, with high intra- and inter-subject reproducibility, in one IC exhibiting a transiently task-related activation in the 'face' region of the primary sensorimotor cortex. This suggests that in addition to or as part of the mirror system, somatotopic regions of the sensorimotor cortex are involved in disambiguating the perception of a moving body part. Finally, we show that the same classification algorithm can be successfully applied, without re-training, to fMRI collected using acquisition parameters, stimulation modality and timing considerably different from those used for training.

Algorithms↗