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At least 19 recordsLinked to original sources
PubMed1983

An anatomical study of the effects of unilateral removal of sensorimotor cortex in infant monkeys on the subcortical projections of the contralateral sensorimotor cortex.

Following removal of the motor or sensorimotor cortex in infant monkeys the projections of the remaining motor or sensorimotor cortex have been studied after long-term survival to look for anomalous projections from these areas. The patterns of degeneration resulting from lesions of the remaining motor or sensorimotor cortex corresponded to those found in normal adult monkeys in the spinal cord, pontine nuclei, superior colliculus, parvocellular red nucleus, subthalamic nucleus and thalamus. Sparse degeneration was found in the magnocellular part of the contralateral red nucleus which has not been described in normal animals and there is also the possibility of an increase in the crossed corticostriate projection. Infant monkeys do not form anomalous projections comparable to those found in the rat following neonatal sensorimotor cortex lesions.

Animals↗
PubMed1999

Multiple synapse formation in the motor cortex opposite unilateral sensorimotor cortex lesions in adult rats.

Unilateral damage to the forelimb region of the sensorimotor cortex (FLsmc) in adult rats has previously been found to result in dendritic growth and synaptogenesis in layer V of the contralateral motor cortex. The neuronal growth appears to be mediated in part by lesion-induced changes in the use of the forelimbs. Whether these neuronal changes involve alterations in the structure and/or configuration of synaptic connections in layer V has not previously been investigated. The present study used stereological measures to characterize structural alterations in axonal processes and synaptic connections using electron micrographs generated in a previous study of the motor cortex contralateral to FLsmc lesions. Of primary interest were synapses formed by multiple synaptic boutons (MSBs), which have recently been found to be a major component of experience-related neocortical plasticity, and synapses with perforated postsynaptic densities (PSDs), which are putatively associated with enhanced synaptic efficacy. In comparison with sham-operated rats, there was an increase in the proportion and ratio of synapses to neurons formed by MSBs and in synapses with perforated PSDs at 30 days after the lesions. Furthermore, perforated synapses formed by MSBs were markedly increased at 18 and 30 days after the lesion in comparison with sham-operated rats. Preceding these synaptic structural changes (at 10 days postlesion), myelinated axons were reduced in volume fraction and volume per neuron in comparison with sham-operated rats but returned to normal levels at subsequent time points. These results are consistent with a lesion-induced degeneration and subsequent sprouting of axons. Together, these data indicate that a major restructuring of synaptic connectivity occurs in the cortex opposite FLsmc lesions in adult animals. This lesion-induced restructuring may be guided by ongoing changes in the use of the forelimbs.

Animals↗
PubMed1996

Synaptogenesis and dendritic growth in the cortex opposite unilateral sensorimotor cortex damage in adult rats: a quantitative electron microscopic examination.

Unilateral lesions of the forelimb area of the sensorimotor cortex in adult rats resulted in time-dependent increases in the number of synapses per neuron and the volume and membrane surface area of dendritic processes per neuron within layer V of the contralateral motor cortex in comparison to sham-operated rats. Based on previous findings of a behavioral relationship with increased dendritic arborization, these changes may be related to lesion-induced compensatory changes in the use of the non-impaired (ipsilateral to the lesion) forelimb.

Age Factors↗
PubMed2006

Behavioral recovery from unilateral photothrombotic infarcts of the forelimb sensorimotor cortex in rats: role of the contralateral cortex.

During sensorimotor recovery following stroke ipsi- and contralesional alterations in brain function have been characterized in patients as well as animal models of focal ischemia, but the contribution of these bilateral processes to the functional improvement is only poorly understood. Here we examined the role of the homotopic contralateral cortex for sensorimotor recovery after focal ischemic infarcts at different time periods after the insult. One group of animals received a unilateral single photothrombotic infarct in the forelimb sensorimotor cortex, while four additional groups received a second lesion in the contralateral homotopic cortex either immediately or 2 days, 7 days, or 10 days after the first infarct. The time course of functional recovery of the impaired forelimbs was assessed using different sensorimotor scores: forelimb-activity during exploratory behavior and frequency of forelimb-sliding in the glass cylinder as well as forelimb misplacement during grid walking. Focal infarcts in the forelimb sensorimotor cortex area significantly impaired the function of the contralateral forelimb in these different behavioral tests. The subsequent damage of the contralateral homotopic forelimb sensorimotor cortex only affected the forelimb opposite to the new lesion but did not reinstate the original deficit. The time course of sensorimotor recovery after bilateral sequential cortical infarcts did not significantly differ from animals with unilateral single lesions. These data indicate that following small ischemic cortical infarcts in the forelimb sensorimotor cortex the contralateral cortex homotopic to the lesion plays only a minor role for functional recovery.

Animals↗
PubMed1991

The emergence of architectonic field structure and areal borders in developing monkey sensorimotor cortex.

Adult monkey sensorimotor cortex consists of several structurally and functionally distinct areas. The developmental sequence through which the characteristic architectonic features and the borders of these areas become resolved was examined in a series of fetal, postnatal and adult monkeys by using Nissl staining, cytochrome oxidase and acetylcholinesterase histochemistry, and immunocytochemistry for GABA and the neuropeptides somatostatin, neuropeptide Y, substance P and cholecystokinin. At the youngest fetal age examined (E110), the pre- and postcentral gyri possess six clearly delineated cellular layers; populations of GABA- and neuropeptide-immunoreactive cells can be identified, but their somatic sensory cortex at E110 lacks areal cytoarchitectonic parcellation. Despite the apparent homogeneity in the cytoarchitecture of the somatic sensory cortex, incipient areal borders are revealed by staining for cytochrome oxidase and acetylcholinesterase activity, and by staining immunocytochemically for several neuropeptides. The motor cortex at E110 differs from that in adults by the presence of a prominent layer IV; a clear cytoarchitectonic border between areas 3a and 4 is detectable at E110, which is also revealed by chemoarchitectonic markers. With increasing age, the characteristic architectonic features gradually emerge and areal cytoarchitectonic borders appear, becoming adult-like by early postnatal ages. The gradual changes in cytoarchitecture are paralleled by redistributions of GABA- and neuropeptide-immunoreactive cells and fiber plexuses. The data demonstrate that the progressive refinement in cytoarchitectonic features and in the distributions of neurotransmitter- and peptide-containing cells occurs primarily during the latter third of gestation. The major changes are temporally coincident with the ingrowth of afferent axonal systems, suggesting that the establishment of connectivity may be capable of modulating finer details of structural or molecular phenotype, particularly intra-areal cytoarchitectonic features and neurotransmitter or peptide expression.

Acetylcholinesterase↗
PubMed2006

Relationship between intracerebral gamma oscillations and slow potentials in the human sensorimotor cortex.

Changes in sensorimotor rhythms (mu, beta and gamma) and movement-related cortical potentials (MRCPs) are both generated principally by the contralateral sensorimotor areas during the execution of self-paced movement. They appear to reflect movement control mechanisms, which remain partially unclear. With the aim of better understanding their sources and significance, we recorded MRCPs and sensorimotor rhythms during and after self-paced movement using intracerebral electrodes in eight epileptic subjects investigated by stereoelectroencephalography. The results showed that: (i) there is a strong spatial relationship between the late components of movement--the so-called motor potential (MP) and post-movement complex (PMc)--and gamma event-related synchronization (ERS) within the 40-60 Hz band, as the MP/PMc always occurred in contacts displaying gamma ERS (the primary sensorimotor areas), whereas mu and beta reactivities were more diffuse; and (ii) MPs and PMc are both generated by the primary motor and somatosensory areas, but with distinct sources. Hence, this could mean that kinesthesic sensory afferences project to neurons other than those firing during the pyramidal tract volley. The PMc and low gamma ERS represent two electrophysiological facets of kinesthesic feedback from the joints and muscles involved in the movement to the sensorimotor cortex. It could be suggested that gamma oscillations within the 40-60 Hz band could serve to synchronize the activities of the various neuronal populations involved in control of the ongoing movement.

Action Potentials↗
PubMed1995

Behavioural consequences of frontal cortex grafts and enriched environments after sensorimotor cortex lesions.

Past studies have experienced difficulty in achieving graft survival and behavioural recovery after sensorimotor cortex lesions. In the present work, adult female rats trained preoperatively to cross a narrow beam for food reward were maintained in standard group cages or an enriched environment, commencing one week after a unilateral lesion. One month post-lesion, half of these rats received multiple suspension grafts of (E20) fetal frontal cortex, placed adjacent to the lesion cavity, and 8 days later recovery of beam-walking skills was examined for a six-week period. The grafts survived in all cases with an appropriate lesion, a notable result given the one month lesion-graft delay, but graft volume was not influenced by postoperative environment. The substantial lesion-induced deficits evident just prior to differential housing showed a marked reduction by the start of post-graft testing, but relative to intact controls a persistent deficit in foot slip errors occurred in all lesion groups. Irrespective of graft status, postoperative enrichment prevented the occurrence of severe foot slips, especially early in retraining. The frontal grafts, however, enhanced beam-walking recovery by reducing the overall frequency of foot slips on early post-grafting sessions, an effect we suggest is related to graft-derived trophic influences, but this measure was not significantly improved by postoperative enrichment.

Animals↗
PubMed1987

Consequences of damage to the sensorimotor cortex in neonatal and adult cats. II. Maintenance of exuberant projections.

After chronic sensorimotor cortex ablations, sparing and greater recovery of function were seen in neonatally operated cats compared with adult operated cats. These results suggested that undamaged cortex in neonatal operates might display projections different from those of adult operates. Injections of horseradish peroxidase-wheat germ agglutinin (HRP-WGA) were made in ipsilateral parietal cortex adjacent to the sensorimotor cortex ablations or in the contralateral sensorimotor cortex. No changes in the projections of the parietal cortex were seen in operated cats or in the projections of the undamaged sensorimotor cortical projections of adult operates. In contrast, the intact sensorimotor cortex of neonatal operates exhibited crossed corticothalamic and corticorubral projections not present in normal or adult operated animals, whereas the corticospinal tract (CST) was unchanged by the ablations. Analysis of neurons within the ventroanterior-ventrolateral nuclear complex of the thalamus ipsilateral to the ablation showed that the surviving cells of neonatal operates were equal in number but were, on average, larger than those of normals and adult operates. Some neurons in neonatal operates were larger than any seen in adult operates and normals. Injections of HRP/WGA were also made into the sensorimotor cortex of normal newborn animals. Dense bilateral corticothalamic and corticorubral projections were present. The CST had extended to lumbar levels by the day of birth but projections to the grey matter were sparse. Thus, bilateral projections seen in neonatal operates probably represent retention of some exuberant projections present in normal neonatal animals. The CST which exhibited no exuberant projection was unchanged by the lesion. The crossed corticothalamic and corticorubral projections are likely to play a role in sparing and recovery of function particularly in sparing of contact placing.

Animals↗
PubMed1982

[Neuronal responses of the intact cortex and isolated strips of the sensorimotor cortex to systemic administration of thyroxine].

The pattern of neuronal responses to alterations in hormonal homeostasis was specified. A study was made of neuronal responses of intact and neuronally isolated strips of the sensorimotor cortex (ISC) to intravenous injection of thyroxine. The neuronal response of the ISC was found to differ substantially from the response of intact cortical neurons. Less percentage of the responding neurons was registered in the ISC. The responses were considerably shortened, while the neurons discharged at a lower frequency. The differences indicate that, as compared to subcortical structures, the cortical neurons are less susceptible to blood hormones. It is emphasized that subcortical structures, particularly the hypothalamus are of major importance for transmission of hormonal influences to the brain cortex.

Action Potentials↗
PubMed1998

Perirolandic cortex in infants: signal intensity on MR images as a landmark of the sensorimotor cortex.

PURPOSE: To correlate the perirolandic low signal intensity seen on T2-weighted magnetic resonance (MR) images in neonates and infants with the anatomically located sensorimotor cortex. MATERIALS AND METHODS: Axial T2-weighted MR images of 146 consecutive patients less than 6 months old were reviewed. The sensorimotor cortex was located by identifying the central sulcus. Two independent readers attempted to identify the central sulcus using two anatomic methods independently and in combination. The location of the central sulcus was compared with that of the perirolandic low signal intensity. RESULTS: Seventy-two normal hemispheres in 36 patients and 91 abnormal hemispheres in 47 patients showed clear perirolandic low signal intensity. The central sulcus was located anatomically in 70 and 72 normal hemispheres (97% and 100%, respectively) and 90 and 91 abnormal hemispheres (99% and 100%, respectively). In all normal hemispheres, the identified central sulcus correlated with the perirolandic low signal intensity. In contrast, an apparent mismatch was found in two hemispheres in a patient with Dandy-Walker syndrome. CONCLUSION: The perirolandic low signal intensity seen on T2-weighted MR images is located exactly in the anatomic sensorimotor cortex in normal brains, whereas a mismatch can occur in abnormal brains.

Bacterial Infections↗
PubMed1990

[The effect of the selective blocking of synaptic transmission in the parafascicular complex on the neuronal activity of the sensorimotor cortex].

Peculiarities of spike responses of the sensorimotor cortex neurons and conditional activity induced by blockade of noradrenergic and serotoninergic inputs of the PF complex (CM-PF) have been studied in chronic experiments on cats with a preliminarily conditioned placing reaction to an auditory stimulus--a click. It is shown that an increase in the background activity of neurons of the sensorimotor cortex was caused by microinjections of obsidan, an adrenergic blocker, while depression--by microinjections of lysergoamid, a serotonin blocker. The effect of both blockers on the neuronal reactions evoked by conditional auditory stimulus was the same (depression). Both conditional placing and unconditional one were removed by partial blockade of monoaminergic inputs for 30-60 min. A conclusion is made that the character of the influence of the monoaminergic system on the sensorimotor cortex is determined not only by direct, but also by indirect influences due to neurons of the CM-PF complex of thalamic nuclei.

Acoustic Stimulation↗
PubMed1991

Intraoperative localization of sensorimotor cortex by cortical somatosensory evoked potentials.

Intraoperative cortical somatosensory potentials were evoked to localize the sensorimotor cortex under general anesthesia by contralateral median nerve stimulation in 12 patients. Eight patients underwent an excision of the epileptogenic focus for intractable complex partial seizures and the other 4 patients underwent tumor surgery following successful localization of the sensorimotor cortex. The relationships between the somatosensory evoked potentials and the anatomy of the sensorimotor cortex allowed rapid and accurate localization of the sensorimotor hand area: (1) the P2 recorded from the postcentral gyrus had a positivity of 49.0 microV on the average with a mean latency of 26.9 msec; (2) the N1 and P2 consistently showed phase-reversal across the Rolandic fissure; and (3) maximum SEP amplitudes were recorded from the hand representation area of the sensorimotor cortex. The neurophysiological and neurosurgical results demonstrate the feasibility of recording cortical SEP's under general anesthesia and the improvement of safety in surgical excisions near the sensorimotor cortex.

Adolescent↗
PubMed1988

[Effect of alcoholic intoxication of female mice prior to pregnancy on the ultrastructure of neurons in the sensorimotor cortex of the progeny].

Sensorimotor cortex in the offspring of female rats alcoholized in the prepregnancy period revealed signs of delayed neuronal development and dystrophic changes in the neurons especially on the 14th day after birth. In 21-day-old animals the reparative changes increased, but normalization of neuronal ultrastructure was not observed. The dystrophic changes suggest that prenatal brain hypoxia plays an important role in the pathogenesis of alcohol-induced neuronal lesions in the offspring.

Animals↗
PubMed1994

Location of hand function in the sensorimotor cortex: MR and functional correlation.

PURPOSE: To determine the location of hand function in the sensorimotor cortex using MR and positron emission tomography imaging studies. METHODS: Anatomic and physiological methods were used for this study. Anatomic study was based on the MR analysis of 22 subjects. The length of the sensorimotor cortex was measured in the axial and sagittal planes. Physiologic study was based on the positron emission tomography studies of 4 subjects. Each of the studies was correlated with MR. RESULTS: We found that the superior genu of the central sulcus corresponds to hand function in the sensorimotor cortex. This level may prove useful for any clinical correlations or for surgery. CONCLUSIONS: From this study, the hand function area in the sensorimotor cortex is easily understood with its characteristic shape in axial MR scan. The comparison of MR and positron emission tomography data clearly show anatomic correlations. This may be applied to the functional mapping of the pathologic studies in the sensorimotor cortex regions.

Adult↗
PubMed1985

Projection of phrenic nerve afferents to the cat sensorimotor cortex.

The projection of phrenic nerve afferents to the sensorimotor cortex was studied in cats. The results of these experiments demonstrate that stimulation of phrenic nerve afferents elicits cortical evoked potentials (CEPs) in the sensorimotor cortex of cats. Cortical foci for CEPs classified as primary were found in areas 3b, 3a and 4 gamma. These foci were located medial to forelimb and lateral to hindlimb afferent representations in the sensorimotor cortex.

Afferent Pathways↗
PubMed1997

Somatosensory evoked potential identification of sensorimotor cortex in removal of intracranial neoplasms.

OBJECTIVE: To assess the ease and reliability of routine use of somatosensory evoked potentials (SSEPs) for identification of sensorimotor cortex in brain tumour removal and to document its influence on the performance and outcome of surgery. METHODS: SSEPs in response to contralateral median nerve stimulation were recorded from the cortical surface by means of a four lead electrode strip. Polarity reversal of short latency SSEP waves was used to identify the position of the central sulcus in 46 consecutive craniotomies for removal of metastases, gliomas, or meningiomas located in, near, or overlying sensorimotor cortex. RESULTS: SSEPs were successfully recorded in 43/46 cases (94%) with demonstration of polarity reversal in 42/43 (98%). SSEP localization led to modification of 14/42 (33%) procedures, most frequently because of either displacement or involvement of sensorimotor cortex by tumour. Six patients (14%) developed new neurological deficits but none of these was attributable to incorrect identification of sensorimotor cortex. CONCLUSIONS: SSEP polarity reversal is a simple, reliable, accurate, and inexpensive method of localizing sensorimotor cortex under general anaesthesia. Correct identification is possible when sensorimotor cortex is displaced or when surface anatomy is obscured by tumour. Routine use of this technique should be considered in all procedures for lesions located near the central sulcus.

Adult↗
PubMed1989

Functional organization of interzonal transcallosal connections in the sensorimotor cortex.

Transcallosal evoked potentials (EP) in cat sensorimotor cortex, arising in response to stimulation of the visual or auditory zone of an opposite hemisphere, were investigated. Interzonal transcallosal responses (TCR) were shown to be present along the entire surface of the sensorimotor cortex. Videomotor EPs were mainly in the form of responses with initial negativity. The latent periods of audiomotor EPs were longer than those of videomotor EPs. Negative-positive videomotor responses had greater amplitudes as compared to the amplitudes of synphasic or audiomotor EPs. Responses with initial positivity, on the contrary, had greater amplitudes during Field AI stimulation than they had during the stimulation of Field 19. Interzonal transcallosal responses in MI zone were characterized by interhemispheric asymmetry. In a per-pair comparison of the amplitudes of response components, individual asymmetry was revealed for videomotor EPs. Audiomotor responses in the majority of investigated animals were of greater magnitude in the left hemisphere. The left hemisphere dominance for audiomotor EPs was mainly observed in females, whereas in males the asymmetry revealed was individual. It is suggested that the peculiarities of the interhemispheric asymmetry of interzonal audio- and videomotor functional transcallosal connections are determined by specificity of the intrazonal asymmetry of transcallosal streams in projection and association cortical areas.

Animals↗