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 1,585 records · Page 88Linked to original sources
PubMed2003

Intraoperative functional MRI as a new approach to monitor deep brain stimulation in Parkinson's disease.

This article deals with technical aspects of intraoperative functional magnetic resonance imaging (fMRI) for monitoring the effect of deep brain stimulation (DBS) in a patient with Parkinson's disease. Under motor activation, therapeutic high-frequency stimulation of the subthalamic nucleus was accompanied by an activation decrease in the contralateral primary sensorimotor cortex and the ipsilateral cerebellum. Furthermore, an activation increase in the contralateral basal ganglia and insula region were detected. These findings demonstrate that fMRI constitutes a promising clinical application for investigating brain activity changes induced by DBS.

Aged↗
PubMed2002

Dendritic architecture of corticothalamic neurons in a rat model of microgyria.

MATERIALS AND METHODS: Freezing lesions of the sensorimotor cortex resembling focal human microgyria were carried out in newborn rats on first postnatal day (P1). The fine architecture of dendritic trees of corticothalamic neurons was studied in microgyric animals on P90. RESULTS AND DISCUSSION: Compared with controls, layer 5 corticothalamic neurons located in the cortex surrounding the experimental lesion display longer basal dendrites. This finding is discussed with reference to earlier results on dendrites of layer 3 associative neurons, which, in contrast to those of corticothalamic neurons, appear to be markedly simplified.

Animals↗
PubMed2003

Neurological associations of absent P60 component of the posterior tibial nerve somatosensory evoked potential.

The cortically generated P60 component of the posterior tibial nerve somatosensory evoked potential (PTSEP) is occasionally found to be absent in neurological patients,while the preceding P40 is preserved ("Absent P60" pattern). A retrospective analysis of 24 such cases showed them to represent a different clinical population from that represented by 24 age- and sex-matched but otherwise unselected patients with entirely normal PTSEPs. The most frequent diagnoses of the patients with normal PTSEPs (conversion disorder and definite or suspected multiple sclerosis) were significantly less prevalent in the patients with the Absent P60 pattern, while miscellaneous other diseases affecting the peripheral and/or central sensory pathways were more frequent. In comparison with a second matched patient group with abnormal P40 in addition to P60, the patients with the Absent P60 pattern had a significantly lower incidence of "large fibre" sensory deficits (impaired vibration and/or joint-position sense). The incidence of "small fibre" deficits (impaired pain and/or temperature sensation) was similar in both groups with PTSEP changes. In conjunction with previously published findings in normal subjects, the data suggest that the P60 is a late response of the primary sensorimotor cortex due to activation of large diameter myelinated sensory fibres, but which is also tonically influenced by small fibre input. The Absent P60 pattern may be recognized as a distinct PTSEP abnormality, although its occurrence in some normal individuals should be noted.

Adult↗
PubMed2005

Sensorimotor integration in patients with parkinsonian type multisystem atrophy.

Sensorimotor integration is an essential feature of the central nervous system that contributes to the accurate performance of motor tasks. Some patients with multiple system atrophy with parkinsonian features (MSAp) exhibit clinical signs compatible with an abnormal central nervous system excitability to somatosensory inputs, such as action myoclonus or enhanced cutaneo-muscular reflexes. To investigate further the site where such dysfunction in sensorimotor integration takes place, we examined the inhibitory effects of a cutaneous afferent volley at two different levels of the motor system in 10 MSAp patients and in 10 age-matched healthy volunteers. Electrical digital nerve stimuli were given as the conditioning stimulus for the motor evoked potentials (MEP) elicited by transcranial magnetic stimulation in hand muscles, and for the blink reflex responses obtained in the orbicularis oculi muscles by supraorbital nerve stimulation. Intervals for the conditioning were 20 to 50 ms for the MEP and 90 to 110 ms for the blink reflex. The MEP was significantly inhibited in test trials in healthy volunteers, reaching a mean of 32% of the baseline values at the ISI of 35 ms. Significant inhibition occurred also in the blink reflex, in which the R2 response was a mean of 12% of baseline values at the ISI of 100 ms. The inhibitory effects were abnormally reduced in 8 patients on the MEP, and in 7 patients on the blink reflex. There were significant group differences between patients and control subjects in the size of the conditioned MEP and blink reflex. These results suggest that sensorimotor integration is abnormal in patients with MSAp in at least two central nervous system sites: the sensorimotor cortex, and the brainstem reticular formation.

Aged↗
PubMed1997

[18F]-fluorodeoxyglucose-positron emission tomography findings in protein infants with severe periventricular leukomalacia and hypsarrhythmia.

UNLABELLED: Two preterm infants with extensive periventricular leukomalacia (PVL) were examined by [18F]-fluorodeoxyglucose-positron emission tomography (FDG-PET) at the corrected ages of 18 and 34 days. They showed similar clinical courses including oculoclonic seizure, hypsarrhythmia and severe mental retardation, in addition, to spastic quadriplegia. FDG-PET study of these two infants with severe PVL disclosed poorly developed metabolic activity in the primary sensorimotor cortex, while the MRI images displayed only periventricular white matter lesions. CONCLUSIONS: Positron emission tomography may disclose cortical involvement in infants with severe periventricular leukomalacia.

Blood Glucose↗
PubMed1999

Demonstration of cerebral plasticity by intra-operative neurophysiological monitoring: report of an uncommon case.

It has been postulated long ago that "eloquent" areas shift their location in patients with arteriovenous malformations (AVM). Obviously the "motor region" in not located in the precentral gyrus in a patient with an AVM in the "motor region". We report on the case of a 15-year old boy with an AVM in the left sensorimotor cortex, in whom intra-operative mapping showed an inexcitability of the precentral gyrus, while stimulation of the cortex anterior to the primary motor cortex elicited motor responses. This indicates that motor function was translocated from the primary to the supplementary motor cortex. Surgery was performed under general anaesthesia. Neurophysiological monitoring was performed throughout surgery. The central sulcus was identified by phase reversal of the somatosensory evoked potentials. The motor cortex was mapped by direct high-frequency (500 Hz) monopolar anodal stimulation. In the patient herein reported, stimulation of the "anatomically" defined primary motor cortex induced no motor response, as expected. Motor response was elicited only by stimulation of the cortex anterior to the precentral gyrus. There was no postoperative deterioration of motor function. These observations indicate that the precentral gyrus was functionally "useless". The motor region was relocated into more rostral areas in the supplementary motor cortex. This translocation of function in the presence of an AVM indicates cerebral plasticity.

Adolescent↗
PubMed2002

Magnetoencephalography in presurgical epilepsy evaluation.

The introduction of whole-head magnetoencephalography (MEG) systems facilitating simultaneous recording from the entire brain surface has led to a major breakthrough of MEG in presurgical epilepsy evaluation. Localizations of the interictal spike zone with MEG showed excellent agreement with invasive electrical recordings, were useful to clarify the spatial relationship of the irritative spike zone to structural lesions, and could attribute epileptic activity to lobar subcompartments both in temporal lobe and extratemporal epilepsy. MEG was especially useful for the study of patients with non-lesional neocortical epilepsy and of patients with large lesions, where it provided unique information on the epileptogenic zone. It could reliably localize sensorimotor cortex prior to surgical procedures adjacent to central fissure. MEG language mapping yielded concordant results with the Wada test and cortical stimulation studies. MEG localizations of epileptic activity and essential brain regions were successfully integrated into frameless stereotaxy systems providing accurate functional information intraoperatively. Because MEG and EEG yield both complementary and confirmatory information, combined MEG-EEG recordings in conjunction with advanced source modeling techniques will further improve the noninvasive evaluation of epilepsy patients and constantly reduce the need for invasive procedures.

Brain↗
PubMed2006

Cortical modulation of dorsal column nuclei: a computational study.

We present a computational study aimed at exploring the sensorimotor cortex modulation of the behaviour of dorsal column nuclei, specifically the impact of synaptic parameters, during both sleep and waking conditions. On the basis of the circuit proposed by Canedo et al. (2000), we have developed realistic computational models that have been tested with simultaneous electrocorticographic as well as intracellular cuneate recordings performed in anaesthetized cats. The results show that, (1) under sleep conditions, the model can block the transmission of afferent sensory information and, (2) operations expected during wakefulness, such as filtering and facilitation, can be performed if synaptic parameters are appropriately tuned.

Animals↗
PubMed2006

A special case of learning disorder in isolant rats as a model of disintegration.

The combination of two factors - isolation and ontogenesis (starting from 21 days) and subsequent training of rats to a cyclical habit - could in some animals (30%) lead to the formation of unusual behavioral strategies consisting of maintenance of the cyclical habit without reinforcement with food. This dissociation from the vital motivation is regarded as an analog of the disintegration phenomenon, a key step in psychoneurotic disorders. The most common type of disturbance in isolated animals was suppression of searching activity, with extreme learning difficulty, though a training process including a two-month break led to a significant increase in motor-searching activity in this situation. These behavioral abnormalities were accompanied by morphological changes in the sensorimotor cortex of the brain, with a relative thinning of layer 5 and selective decreases in the density of satellite glial cells and deviations from the normal correlational relationships between behavioral and neuroglial measures.

Animals↗
PubMed2005

Injection of glutamate into the pedunculopontine tegmental nuclei of anesthetized rat causes respiratory dysrhythmia and alters EEG and EMG power.

The pedunculopontine tegmental nucleus (PPT) has been shown to have important functions relevant to the regulation of behavioral states and various motor control systems, including breathing control. Our previous work has shown that the activation of neurons within the PPT, a structure that is typically active during rapid eye movement (REM) sleep, can produce respiratory disturbances in freely moving and anesthetized rats. The aim of this study was to test the hypothesis that respiratory modulation by the PPT in anesthetized rats can be evoked in the absence of other signs of an REM-sleep-like state. We characterized electroencephalogram (EEG) and electromyogram (EMG) changes during respiratory disturbances induced by glutamatergic stimulation of the PPT in spontaneously breathing, adult male Sprague-Dawley rats anesthetized with a ketamine/xylazine combination or with nembutal. Respiratory movements were monitored by a piezoelectric strain gauge. Two-barrel glass pipettes were used to pressure inject glutamate, to probe for respiratory effective sites within the PPT, and to inject oil red dye at the end of the experiments for histological verification of the injection sites. The EEGs were recorded from the sensorimotor cortex, hippocampus, and from the pons contralateral from the injection site. The EMGs were recorded from the genioglossus muscle. The initial response to glutamate injection into the respiratory modulating region of the PPT was always a respiratory pattern disturbance. Subsequent activation of EMG and EEG often occurred in ketamine/xylazine-anesthetized rats, but REM-sleep-like patterns were not observed. Respiratory pattern and EMG power changes in nembutal-anesthetized rats were similar, but EEG activation was never observed. Thus, we conclude that respiratory suppression produced by the local activation of PPT neurons may not necessarily be accompanied by an REM-sleep-like cortical state in this anesthetized model.

Anesthesia↗
PubMed2006

Modulation of respiratory pattern and upper airway muscle activity by the pedunculopontine tegmentum: role of NMDA receptors.

The pedunculopontine tegmental nucleus (PPT) is postulated to have important functions relevant to the regulation of rapid eye movement (REM) sleep and arousal, and various motor control systems including respiration. We have recently shown that pharmacologic activation of a neuronal subpopulation within the PPT, induced by micropipette injection of glutamate in nanoliter volumes, can produce respiratory rhythm disturbances and changes in genioglossus muscle activity in anesthetized rats. The aim of this study was to determine whether the respiratory pattern disturbance and increased genioglossus muscle tone induced by glutamate injection within the PPT are mediated by activation of N-methyl-D-aspartate (NMDA) receptors within the PPT. Experiments were performed in eight adult male spontaneously breathing Sprague-Dawley rats anesthetized using nembutal. Respiratory movements were monitored by piezoelectric strain gauge. Three-barrel glass pipettes were used to pressure inject glutamate (as a probe for respiratory modulating sites), ketamine (an NMDA channel blocker), and oil-red dye (to aid in histological verification of the injection sites) within the PPT. Electroencephalograms were recorded from the sensorimotor cortex, the hippocampus, and the pons, contralateral to the injection site. Electromyograms (EMGs) were recorded from the genioglossus muscle. The typical response to glutamate injection within the PPT respiratory-modulating region was immediate apnea followed by tachypnea and increased genioglossal tonic activity. The noncompetitive NMDA receptor channel-antagonist ketamine, injected at the same site and in the same volume as glutamate (5 nl), blocked respiratory dysrhythmia and genioglossal EMG responses to subsequent glutamate injections. For the first time, the present results suggest that respiratory rhythm and upper airway muscle tone are controlled by the activation of pedunculopontine tegmental nucleus NMDA receptors.

Animals↗
PubMed1975

Retrograde cortical aand axonal changes following lesions of the pyramidal tract.

Following lesions of the pyramidal tract in hamsters, retrograde changes were studied in the sensorimotor cortex and in the pyramidal tract axons proximal to the lesion, at survival times ranging from 2 weeks to 14 months. Severe cell shrinkage occurred in layer 5 pyramidal neurons as early as 2 weeks, but there was no cell loss among these neurons even with long survival times. Use of the Fink-Heimer method for degenerating axons revealed that the pyramidal tract proximal to the lesion had undergone a retrograde axon degeneration which, in some respects, resembled anterograde degeneration. The retrograde axon degeneration began at the lesion site and advanced slowly rostralwards with time involving increasingly greater numbers of fibers. However, even at the longest survival times the degeneration fell off markedly at pontine levels. The results indicate that this process represents a true retrograde fiber degeneration (as opposed to an indirect Wallerian degeneration) which appears to reach a point of equilibrium such that a partially shrunken pyramidal cell is maintaining a partially degenerated axon.

Animals↗
PubMed1976

EEG development in normal and undernourished rats.

The development of EEG was studied in normal and undernourished white and black hooded rats, aged 9-30 days. Undernutrition of the young was accomplished by underfeeding the mothers with restricted amounts of a standard laboratory food from the 7th day after conception until the 21st day after birth. Bipolar EEG recordings were made from the sensorimotor cortex and from the visual cortex in rats with chronically implanted electrodes. The EEG was recorded, stored on magnetic tape and analyzed for amplitude distributions and frequency spectra. During the recording 3 behavioural states (defined on the basis of behavioural criteria) were distinguished.

Animals↗
PubMed1976

Release of amino acids from the maturing cobalt-induced epileptic focus.

A study was made of the release of excitatory, inhibitory and other amino acids from epileptic foci induced in the sensorimotor cortex of rats by cobalt implantation. A new in vivo superfusion method was employed which gives free movement to the animals and allows study over periods of days and weeks. Most amino acids showed maximum release rates during the first 2 or 3 days after surgery. Glutamate showed maximum release rates during days 3-6 when epileptic limb jerks were at a maximum. This pattern was not seen for other physiologically active amino acids.

Amino Acids↗
PubMed1976

Comparison between red nucleus and precentral neurons during learned movements in the monkey.

Monkeys were trained to depress a hold key for a period of 2 sec. After this hold period, either a red or a green cue lamp appeared in random sequence. The red lamp required the monkey to move his hand from the hold key to a target button within 1 sec of the cue presentation. The green lamp required continued depression of the hold key for 1 sec following presentation of the cue. Correct performance was reinforced with fruit juice. In comparing poststimulus and peri-response latencies of 48 red nucleus (RN) and 46 percentral gyrus (PG) units related to the arm movement triggered by the red lamp, the onset of activity in most RN units occurred after the onset of activity in most PG neurons. For 48 RN neurons, the peak of the distribution of onset times was shifted 120 msec later than for 46 neurons. This delay between PG and RN is even greater than the delay between PG and postcentral gyrus. It is known that RN receives powerful inputs both from the sensorimotor cortex and from cerebellum--and it seems possible that the activity in RN was dependent on the combined action of these two inputs, with sensory feedback from movement (relayed via postcentral gyrus and/or cerebellum) being one input, and a central program from cerebellum and/or precentral gyrus being the other input.

Action Potentials↗
PubMed1977

Protein pattern alterations in hippocampal and cortical cells as a function of training in rats.

The study reports changes in the protein pattern and incorporation of L-[U-14C]-leucine in brain cells of the hippocampus and sensorimotor cortex of rats. The following subcellular fractions were analyzed by SDS-acrylamide gel electrophoresis: plasma membranes, synaptosomal membranes and synaptic mitochondria. Recurring reversal training gave an increased synthesis of synaptosomal membrane proteins with mol. wt. 35,000-45,000 and 60,000 and 100,000 in trained animals compared to active controls. Lesser changes were observed in plasma membrane and synaptic mitochondria fractions. Of the brain areas studied, the hippocampal synaptosomal fraction showed an initial, temporary response, and the cortical cell fractions responded subsequently. Judged from the time sequence of the protein response, it seems that recurrent reversal training induces a change in synaptic protein towards higher molecular weights, suggesting that these changes reflect a modification of the distribution of synaptic protein.

Animals↗
PubMed1979

Activity of postcentral cortical neurons of the monkey during conditioned movements of a deafferented limb.

Unit recordings were performed in the sensorimotor cortex of awake monkeys during performance of learned movements of the contralateral arm. The movements were triggered by a sound stimulus. The neuronal discharge in association with movement was observed before and after deafferentation (C2--T5) of the operant limb. Whereas neurons recorded in the motor cortex (area 4) and in the parietal association cortex (area 5) still modified their activity in relation to movement performed by the deafferented arm, the neurons recorded in the primary sensory cortex (areas3, 1 and 2) showed no activity change in relation to movement after deafferentation. This finding strongly suggests that modification of discharge of postcentral neurons seen during ballistic arm movement is mainly the result of input from the moving limb (peripheral feedback) and not the result of input from other structures of the central nervous system (internal feedback).

Afferent Pathways↗
PubMed1980

The action of gamma-vinyl-GABA and gamma-acetylenic-GABA on the resting and stimulated release of GABA in vivo.

The effects of gamma-vinyl-GABA (4-amino-hex-5-enoic acid, RMI 71754) and gamma-acetylenic-GABA (4-amino-hex-5-ynoic acid, RMI 71645), the selective and irreversible inhibitors of GABA-transaminase (E.C. 2.6.1.19), on the resting and stimulated release of GABA and other amino acids from sensorimotor cortex of rats was studied using a superfusion technique. Administration of a single dose of gamma-vinyl-GABA (1500 mg/kg i.p.) caused the appearance of GABA in superfusate. This reached a maximal peak size after 50 min and remained high for 3 h. gamma-Vinyl-GABA was also released and reached a maximum value after 20 min and decreased to low levels during 3 h. There was no direct parallelism between the time courses of release of GABA and gamma-vinyl-GABA. Also, the amount of GABA released was much larger when the drug was administered by i.p. injection than when applied directly to the cortex surface through the cannula at 100 microM. In the presence of gamma-vinyl-GABA, stimulation of the brachial plexus contralateral to the superfusion cannula increased GABA and glutamate release, but was without effect on gamma-vinyl-GABA itself or any other amino acid. In the presence of gamma-acetylenic-GABA the contralateral stimulation increased significantly only the rate of release of glutamate and the combined peaks of GABA and gamma-acetylenic-GABA. These changes were not observed to follow stimulation of the ipsilateral plexus. Stimulation of either plexus had no detectable action on the rates of release of GABA from the visual cortex. The changes in rates of release of GABA and glutamate due to stimuli were reversible, returning to control levels after cessation of the stimulation.

4-Aminobutyrate Transaminase↗