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 1,171 records · Page 65Linked to original sources
PubMedDate not supplied

[Change in the impulse reactions of sensomotor cortex neurons to combined stimulation of thalamic relay nuclei].

In acute experiments on unanaesthetized cats immobilized with d-tubocurarine, a study was made of the impulse responses of the sensorimotor cortex neurones to stimulation of the thalamic relay nuclei (VPL and VL). Distinct changes of the responses were found as a result of multiple paired stimulations of these thalamic structures. The nature of the changes proved to be different for the responses to the first (VPL) and second (VL) thalamic stimulation: the paired stimulations facilitated the responses to VPL stimulation and suppressed those to the VL stimulation.

Animals↗
PubMed2003

Benign epilepsy with centro-temporal spikes: spike triggered fMRI shows somato-sensory cortex activity.

OBJECTIVE: We performed spike triggered functional MRI (fMRI) in a 12 year old girl with Benign Epilepsy with Centro-temporal Spikes (BECTS) and left-sided spikes. Our aim was to demonstrate the cerebral origin of her interictal spikes. METHODS: EEG was recorded within the 3 Tesla MRI. Whole brain fMRI images were acquired, beginning 2-3 seconds after spikes. Baseline fMRI images were acquired when there were no spikes for 20 seconds. Image sets were compared with the Student's t-test. RESULTS: Ten spike and 20 baseline brain volumes were analysed. Focal activiation was seen in the inferior left sensorimotor cortex near the face area. The anterior cingulate was more active during baseline than spikes. CONCLUSIONS: Left sided epileptiform activity in this patient with BECTS is associated with fMRI activation in the left face region of the somatosensory cortex, which would be consistent with the facial sensorimotor involvement in BECT seizures. The presence of BOLD signal change in other regions raises the possibility that the scalp recorded field of this patient with BECTs may reflect electrical change in more than one brain region.

Adolescent↗
PubMed2002

Human cortical electroencephalography (EEG) rhythms during the observation of simple aimless movements: a high-resolution EEG study.

In the present high-resolution electroencephalographic (EEG) study, we computed event-related desynchronization and synchronization (ERD/ERS) of alpha (about 10 Hz) and beta (about 20 Hz) rhythms in association with the execution (with visual feedback) and observation of brisk unilateral right and left aimless finger movements. A first scope was to test the topographical "functional equivalence" of cortical rhythmicity related to movement execution and observation, which would represent an ideal cortical observation/execution matching system. A second scope was to evaluate the hypothesis of a left or right hemisphere prevalence of the cortical rhythmicity related to the movement observation compared to the movement execution. EEG (128 electrodes) was recorded in 10 healthy right-handed volunteers. Surface Laplacian estimation spatially enhanced EEG data over a MRI-constraint head model. Under both conditions, ERD peaked during the movement execution or observation and was replaced by a ERS "rebound" or "recovery," which peaked during the postevent period. Topographical results are in favor of a "functional equivalence" (i.e., similar ERD/ERS values in magnitude and timing) of alpha and beta rhythmicity in central scalp regions overlying premotor/primary sensorimotor cortex. On the contrary, the functional equivalence of alpha rhythmicity was negligible (i.e., different ERD/ERS values in magnitude and timing) in parietal-occipital scalp regions overlying posterior parietal and parieto-occipital cortex, which could be the neural substrate to distinguish among the own motor intensions and others' aimless movements (i.e., visuomotor transformation integrated with sensorimotor, postural, and kinematics representations). Finally, the pattern of hemispherical cortical rhythmicity did not support a "simple concentration" of movement observation functions in the left or right hemisphere.

Adult↗
PubMed1977

[Mechanisms of participation of the sensomotor cortex in controlling movements].

Neuromorphological, neurophysiological and biomechanical studies in cats revealed cortical structural neuronal modules and functional units of different grades of complexity. Single systemic principle was determined for the sensorimotor cortex activity: structurally organized neuronal modules, having distributed outputs, can be involved in different functional units for purposeful movements. Specific lemniscal signals concerning the movements are the factor which filters inflow of teleceptive information to the neuronal modules and determines exact torographical relations of cortical motor outputs.

Animals↗
PubMed1986

[Postsynaptic reactions of neurons of the sensomotor cortex of the cat during evoked and self-sustained rhythmic activity of the "peak-wave" type].

Intracellular correlates of evoked rhythmic cortical "spike-and-wave" potentials produced in sensorimotor cortex during 3/s stimulation of the thalamic relay nucleus (VPL) and of self-sustained "spike-and-wave" afterdischarges following 8-14/s stimulation of the same nucleus were studied in acute experiments on cats immobilized by myorelaxants. Intracellular recordings of pyramidal tract neurons revealed that different components of evoked "spike-and-wave" potentials, i. e. the spike-like negative wave and the long lasting negative wave, are postsynaptic in origin: the first is due to EPSPs with spike discharges, and the latter--to IPSPs of cortical neurons. Components of "spike-and-wave" afterdischarge mostly reflect the paroxysmal depolarizing shifts of the membrane potential of cortical neurons. After cessation of sustained "spike-and-wave" activity the long-lasting hyperpolarization accompanied by inhibition of spike discharges and subsequent recovery was observed in cortical neurons. It is presumed that the negative wave of the evoked "spike-and-wave" potential as well as slow negative potentials of direct cortical and primary responses reflect IPSPs of deeper parts of pyramidal tract neurons, while the waves of the sustained "spike-and-wave" afterdischarges are due to paroxysmal depolarizing shifts in cortical neurons.

Animals↗
PubMedDate not supplied

[Neuronal spike activity in the sensomotor region of the cerebral cortex upon direct stimulation of emotionally "positive" and "negative" zones of the hypothalamus].

The effect of electrical stimulation of emotionally positive and negative hypothalamic areas on the unit activity of the sensorimotor cortex in rats was studied in order to elucidate physiological mechanisms of emotions as an important factor organizing purposeful animal behaviour. It was found that such an effect is primarily of inhibitory nature and that it does not carry specific information on biological sign of emotion. It is suggested that the formation of adequate behavioural reactions in different emotional states occurs at earlier stages.

Animals↗
PubMed2005

Expectancy of pain is influenced by motor preparation: a high-resolution EEG study of cortical alpha rhythms.

This high-resolution electroencephalographic (EEG) study on alpha event-related desynchronization (ERD) evaluated whether anticipatory activity precedes a sensorimotor interaction induced by concomitant painful stimuli and sensorimotor demand. An omitted-stimulus paradigm induced the expectancy of the painful stimulation at the left hand. In the experimental condition, the painful stimulation was associated with a visual go/no-go task triggering right-hand movements. Two control conditions manipulated the painful sensorimotor interaction variable. Compared with the control conditions, the expectancy of the painful sensorimotor interaction increased the high-band alpha EEG oscillations over the right primary sensorimotor cortex contralateral to the nociceptive stimuli and, to a lesser extent, over the centroparietal midline. These findings suggest that concomitant painful stimuli and simple sensorimotor go/no-go demands affect anticipatory activity as revealed by alpha ERD.

Adult↗
PubMed1991

Secondary generalization in kainic acid-induced focal seizures in unanesthetized cats.

Seizure propagation was studied with different seizure models induced by a kainic acid (KA) microinjection in nonanesthetized cats. These seizures were characterized with a focal onset of seizures followed by secondarily generalized seizures. The mesencephalic reticular formation (MRF) played an important role when an epileptogenic focus was located in a unilateral amygdala, hippocampus, thalamus or visual cortex. When the focus was located in a unilateral lateral geniculate body, a fast, synchronous and bidirectional propagation was observed in the sensorimotor cortex (SMC) and MRF. Brain stem seizure (generalized tonic seizure) was elicited by the KA injection into MRF. The EEG of generalized seizure was characterized by the propagations of seizure activities of MRF immediately to the bilateral SMC and thalamus. The results suggested that MRF participated actively in the generalization of the KA-induced seizures.

Animals↗
PubMed2003

Functional magnetic resonance imaging in a low-field intraoperative scanner.

BACKGROUND: Functional magnetic resonance imaging (fMRI) has been used for preoperative planning and intraoperative surgical navigation. However, most experience to date has been with preoperative images acquired on high-field echoplanar MRI units. We explored the feasibility of acquiring fMRI of the motor cortex with a dedicated low-field intraoperative MRI (iMRI). METHODS: Five healthy volunteers were scanned with the 0.12-tesla PoleStar N-10 iMRI (Odin Medical Technologies, Israel). A finger-tapping motor paradigm was performed with sequential scans, acquired alternately at rest and during activity. In addition, scans were obtained during breath holding alternating with normal breathing. The same paradigms were repeated using a 3-tesla MRI (Siemens Corp., Allandale, N.J., USA). Statistical analysis was performed offline using cross-correlation and cluster techniques. Data were resampled using the 'jackknife' process. The location, number of activated voxels and degrees of statistical significance between the two scanners were compared. RESULTS: With both the 0.12- and 3-tesla imagers, motor cortex activation was seen in all subjects to a significance of p < 0.02 or greater. No clustered pixels were seen outside the sensorimotor cortex. The resampled correlation coefficients were normally distributed, with a mean of 0.56 for both the 0.12- and 3-tesla scanners (standard deviations 0.11 and 0.08, respectively). The breath holding paradigm confirmed that the expected diffuse activation was seen on 0.12- and 3-tesla scans. CONCLUSIONS: Accurate fMRI with a low-field iMRI is feasible. Such data could be acquired immediately before or even during surgery. This would increase the utility of iMRI and allow for updated intraoperative functional imaging, free of the limitations of brain shift.

Adult↗
PubMed1983

Effects of cortical ablations on the turning response evoked by stimulation of the pulvinar-lateralis posterior nucleus complex in the cat.

The role played by the cerebral cortex on turning responses elicited by electrical stimulation of P-LP was studied in 9 chronic cats. In three animals the sensorimotor cortex was bilaterally ablated and the threshold values for inducing a turning response were determined. None of the cats showed abnormal threshold values. In six cats the cerebral cortical area known to have reciprocal anatomical connections with P-LP was unilaterally removed. Seven days after surgery, 50% of the electrodes gave no responses; 25% evoked responses with high thresholds and 25% with normal thresholds. One month after surgery the percentages were: 14, 18 and 68 respectively. Histological findings show important fiber and neuronal degeneration in P-LP. It is postulated that this area of the cerebral cortex plays, a facilitatory role on the P-LP ability to induce turning response and that the recovery of this ability can be explained by the development of P-LP denervation supersensitivity.

Animals↗
PubMed1999

Concordance between functional magnetic resonance imaging and intraoperative language mapping.

Although the correspondence between functional-magnetic resonance imaging (fMRI) representations of the sensorimotor cortex and intraoperative electrophysiology (including somatosensory evoked potential, SSEP, recordings and direct cortical stimulation) has been reported, a similar correspondence between fMRI and intraoperative localization of the language-sensitive cortex is not as well established. The aim of the present study was to evaluate the concordance between fMRI and intraoperative electrophysiology with respect to the localization of the language-sensitive and sensorimotor cortices. We present the results of 21 patients who underwent language and sensorimotor mapping by fMRI and intraoperative electrophysiology including SSEP recordings (n = 21), direct cortical stimulation of motor cortex (n = 15) and direct cortical stimulation of Broca's and Wernicke's area (n = 5). When responses were obtained with both methods, localization of function concurred in all cases. These observations suggest that fMRI represents a reliable preoperative tool for the identification of language-sensitive areas.

Adolescent↗
PubMedDate not supplied

[Conditioned reactions elaborated on the basis of reinforcement by hypothalamic stimulation].

The possibility of elaboration of conditioned emotional reactions on the basis of the stimulation of the hypothalamus, was studied in cats. Reinforcement of a sound (500 c/s) by electrical stimulation of the hypothalamus, which produced reactions of undirected rage, of fear with avoidance, of food search, led to the formation of a conditioned passive defensive reaction, analogous to that based on pain reinforcement. Elaboration of conditioned emotional reactions were blocked by switching off of the sensorimotor cortex by cold. A conclusion is made that during stimulation of the hypothalamus, the state of fear serves as the reinforcing factor and that the sensorimotor neocortical areas participate in the estimation of biological significance of the conditioned signal.

Animals↗
PubMed2006

Phasic increases in cortical beta activity are associated with alterations in sensory processing in the human.

Oscillatory activity in the beta (beta)-frequency band (13-35 Hz) can be recorded over the sensorimotor cortex in humans. It is coherent with electromyographic activity (EMG) during tonic contraction, but whether the cortical beta-oscillations are primarily motor or sensorimotor in function remains unclear. We tested the hypothesis that cortical beta-activity is associated with an up-regulation of sensory inputs that may be relevant to the organization of the motor response. We recorded cortical somatosensory potentials (SEPs) elicited by electrical stimuli to the median nerve at the wrist triggered by increases of electroencephalographic (EEG) beta-activity in the contralateral fronto-central EEG and compared these to SEPs presented at random intervals. The involvement of motor cortex in the triggering EEG activity was confirmed by a simultaneous elevation of cortico-spinal synchrony in the beta-band. The negative cortical evoked potential peaking at 20 ms and the positive evoked potential peaking at 30 ms after median nerve shocks were increased in size when elicited after phasic increases in beta-activity. The functional coupling of sensory and motor cortices in the beta-band was confirmed in recordings of electrocorticographic activity in two patients with chronic pain syndromes, suggesting a means by which beta-activity may simultaneously influence cortical sensory processing, motor output and promote sensory-motor interaction.

Adult↗
PubMed2004

The role of the primary somatosensory cortex in an auditorily paced finger tapping task.

It has been suggested that a simple auditorily paced finger tapping task is associated with three tap-related neuromagnetic sources in the primary sensorimotor cortex contralateral to the tapping hand. Since a first source peaking at approximately 100 ms before tap-onset most likely represents activation of the primary motor cortex (M1) due to the motor command, a second source localized in the primary somatosensory cortex (S1) peaking around tap-onset could be due to kinesthetic feedback of the finger movement. A third source peaking at approximately 100 ms after tap-onset is also localized in the primary somatosensory cortex but inferior to the first S1 source (S1 inferior). The functional meaning of this source is still under debate. On the one hand it has been argued that S1 inferior represents the neuromagnetic correlate of tactile-kinesthetic feedback due to finger-taps and movements. On the other hand the functional meaning of this source could go beyond the sole processing of somatosensory feedback monitoring the temporal distance between tap and pacer (click) to keep the subject in time with the external event. This hypothesis is based on the observation that (1). S1 inferior seems to be coupled equally well to tap and click and (2). that this source might be triggered by the last event (i.e. tap or click). In the present study we re-examined this hypothesis by using a 122-channel whole-head neuromagnetometer. Eight healthy subjects synchronized their right index finger taps to an auditory pacing signal presented with a constant interstimulus interval of 800 ms. To test the hypothesis that the last event triggers S1 inferior we compared neuromagnetic activity following the tap as the first and the last event. In the auditorily paced finger tapping task usually the tap leads over the click (negative asynchrony). Therefore, the tap usually occurs as the first event. Since it has been shown that delivering additional feedback at the time of tap-onset results in a reduced negative asynchrony, in a second run auditory feedback was presented at tap-onset to enhance the number of positive asynchronies (i.e. the tap is the last event). Since no latency differences of S1 inferior associated with positive and negative asynchronies were found, results from the present study do not support the assumption that S1 inferior is triggered by the last event. Moreover, the amplitude of S1 inferior is significantly reduced following positive asynchronies as compared to negative asynchronies. Additionally, tap duration (i.e. the time between tap-onset and tap-offset) is significantly reduced while subjects produce positive asynchronies. Therefore, the amplitude of S1 inferior seems to be modulated by movement kinematics. This observation agrees well with the idea that activation of S1 is solely associated with the processing of somatosensory information. To conclude, our data contradict the hypothesis of an evaluation process localized in the primary somatosensory cortex and substantiate the idea that S1 inferior exclusively represents the processing of somatosensory feedback information.

Acoustic Stimulation↗
PubMed1991

Polarizing currents increase noradrenaline-elicited accumulation of cyclic AMP in rat cerebral cortex.

Cyclic AMP accumulation elicited by noradrenaline was determined in cerebral cortical slices of rats 24 h after an application of weak anodal direct current (anodal polarization) to the surface of the sensorimotor cortex. Noradrenaline-elicited accumulation of cyclic AMP was altered regionally by the anodal polarization in relation to the duration and intensity of the polarizing current. The cyclic AMP accumulation elicited by noradrenaline was highest in the left anterior cortical region including the polarized point under polarization conditions of 0.3 microA for 1.5 h and 3.0 microA for 30 min. Under these two polarization conditions, the cyclic AMP accumulation elicited by noradrenaline was higher than that in the non-polarized control in the same cortical region. Furthermore, the beta-adrenergic antagonist propranolol almost completely reduced the elicited accumulation of cyclic AMP by noradrenaline to the control level. These results suggest that anodal polarization enhances activity of noradrenaline-sensitive cyclic AMP generating systems through beta-adrenergic mechanisms as a function of both duration and intensity in the cerebral cortex and that one polarization event has a long-lasting aftereffect on noradrenaline-sensitive cyclic AMP generating systems in the cerebral cortex.

Animals↗
PubMed2006

Anticonvulsant effects of melatonin on penicillin-induced epileptiform activity in rats.

In the present study, we investigated the effects of melatonin on penicillin-induced epileptiform activity in female Wistar rats. The left cerebral cortex was exposed by craniotomy under urethane anesthesia for the induction of epilepsy by intracortical microinjection of penicillin (200 IU) into the left sensorimotor cortex. The epileptiform activity was analyzed by electrocorticogram (ECoG). Ten minutes before the penicillin injection, 20, 40 or 80 microg of melatonin was administered intracerebroventricularly and ECoG was monitored for 1 h. Forty or 80 microg of melatonin significantly increased the latency to epileptiform activity. Furthermore, melatonin significantly decreased the frequency of spike and spike-wave activity, whereas the amplitude of spikes remained unchanged. In conclusion, data obtained from the present study suggest that melatonin suppresses penicillin-induced epileptiform activity, and it may be an endogenous anticonvulsant.

Action Potentials↗
PubMedDate not supplied

Behavioral and neuroplastic changes in the blind: evidence for functionally relevant cross-modal interactions.

The study of blind individuals provides insight into the brain re-organization and behavioral compensations that occur following sensory deprivation. While behavioral studies have yielded conflicting results in terms of performance levels within the remaining senses, deafferentation of visual cortical areas through peripheral blindness results in clear neuroplastic changes. Most striking is the activation of occipital cortex in response to auditory and tactile stimulation. Indeed, parts of the "unimodal" visual cortex are recruited by other sensory modalities to process sensory information in a functionally relevant manner. In addition, a larger area of the sensorimotor cortex is devoted to the representation of the reading finger in blind Braille readers. The "visual" function of the deafferented occipital cortex is also altered, where transcranial magnetic stimulation-induced phosphenes can be elicited in only 20% of blind subjects. The neural mechanisms underlying these changes remain elusive but recent data showing rapid cross-modal plasticity in blindfolded, sighted subjects argue against the establishment of new connections to explain cross-modal interactions in the blind. Rather, latent pathways that participate in multisensory percepts in sighted subjects might be unmasked and may be potentiated in the event of complete loss of visual input. These issues have important implications for the development of visual prosthesis aimed at restoring some degree of vision in the blind.

Adaptation, Psychological↗
PubMed2002

Synchronous neuronal activity is a signal for axonal sprouting after cortical lesions in the adult.

The ability of the adult brain to form new connections in areas denervated by a lesion (axonal sprouting) is more widespread than previously thought, but mechanisms remain unknown. We have previously demonstrated an unexpected, robust axonal sprouting of contralateral corticostriatal neurons into the denervated striatum after ischemic cortical lesions. We now take advantage of marked differences in the degree of axonal sprouting from contralateral homotypic cortex after two types of cortical lesions to define the role of neuronal activity in this response. Thermal-ischemic lesions (TCL) of sensorimotor cortex, which induce axonal sprouting, produced two sequential patterns of low-frequency, synchronized neuronal activity that are not seen after similarly sized aspiration lesions, which do not induce axonal sprouting. An early rhythm of synchronous neuronal activity occurred in perilesion cortex on day 1 after lesion, with a frequency range of 0.2-2 Hz. A later pattern of activity occurred on days 2 and 3 after lesion, with a frequency range of 0.1-0.4 Hz. This second rhythm synchronized neuronal activity across widespread areas, including the cortical areas that contain the cell bodies of the sprouting axons. TTX was used to block this patterned neuronal activity and determine whether axonal sprouting was prevented. Chronic TTX infusion into the lesion site blocked the synchronous neuronal activity after TCL as well as axonal sprouting. Thus, both after different types of lesions and in the blockade experiments axonal sprouting was strongly correlated with synchronous neuronal activity, suggesting a role for this activity in anatomical reorganization after brain lesion in the adult.

Animals↗