SEARCH · PubMed Health

Results for “Sensorimotor Cortex”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 91 records · Page 5Linked to original sources

PubMed2002

Functional magnetic resonance imaging of the human sensorimotor cortex using a novel vibrotactile stimulator.

The purpose of this study was to investigate the fMRI response of the sensorimotor cortex to a vibration paradigm produced by a novel vibrotactile stimulator. Fifteen contiguous slices covering the sensorimotor cortex parallel to the anterior (AC) and posterior commissure (PC) line were obtained with echoplanar magnetic resonance imaging at 1.5T. Cortical activity in ten healthy subjects (20-45 years) was investigated during vibration (50 Hz) of the palm of the right hand and compared to a finger-to-thumb tapping paradigm. For the vibration paradigm a mechanically driven vibration head was mounted on the palm of the right hand. The new vibration device produces vibration frequencies (1-130 Hz) and displacement amplitudes (0.5-4 mm) suitable to elicit the tonic vibratory reflex. The fMRI measurement during vibratory stimulation revealed activation in the pre- and postcentral gyrus in all subjects. These activations were comparable to the finger-to-thumb tapping paradigm. The advantages of the new MR compatible vibration device include effective transmission of the stimulus and controlled vibration frequencies and intensities. These preliminary fMRI results indicate that vibration can be an alternative paradigm for the evaluation of sensory and motor functions in patients unable to perform active motor paradigms.

Adult↗

PubMed1999

Mechanisms of recovery of dexterity following unilateral lesion of the sensorimotor cortex in adult monkeys.

The mechanisms of recovery of manual dexterity after unilateral lesion of the sensorimotor cortex in adult primates remain a matter of debate. It has been proposed that the cortical zone adjacent to the lesion may take over part of the function of the damaged cortex. To investigate further this possibility, two adult (4-5 years old) macaque monkeys were trained to perform a natural precision-grip task to assess hand dexterity. Intracortical microstimulations (ICMS) were used to map the hand area in M1 on both hemispheres. Ibotenic acid was then injected intracortically to damage the representation in M1 of the preferred hand. Subsequent histological analysis indicated that the hand representation in M1 was indeed lesioned, but, due to a spread of ibotenic acid, the lesion encroached a significant extent of the hand representation in the primary somatosensory cortex. A few minutes after infusion of ibotenic acid, there was a complete loss of dexterity of the preferred hand, which lasted for 1-2 months. Later, a progressive functional recovery of the affected hand took place over a 3- to 4-month period, reaching a stable level corresponding to 30% of the pre-lesion behavioral score. ICMS remapping, conducted nine months after the lesion, revealed that stimulation of the intact or lesioned M1 did not induce any visible movement of the recovered hand. The M1 hand representation on the intact hemisphere was similar to that observed before the lesion. Transient inactivation of the M1 hand/arm areas or of the dorsal and ventral premotor cortical areas (PM) on both hemispheres was undertaken by using microinjections of the GABA-agonist muscimol. Inactivations of M1 had no effect. Inhibition of PM in the damaged hemisphere suppressed the recovered manual dexterity of the affected hand. These results suggest that PM plays a significant role in the incomplete functional recovery of hand dexterity following unilateral damage of the sensorimotor cortex in adult monkeys.

Animals↗

PubMed1989

Pre-movement parietal lobe input to human sensorimotor cortex.

Movement-related cortical potentials (MRPs) were recorded in an auditory dichotic selective attention experiment in patients with focal lesions centered in either posterior superior temporal gyrus (temporal) or in lateral parietal cortex (parietal). Controls and temporal patients generated comparable pre-movement negative shifts (NSs) and motor potentials (MPs), onsetting about 400 ms prior to movement and maximal in amplitude over scalp sites contralateral to button press. Unilateral parietal cortex lesions markedly reduced the NSs but preserved the MP component of the MRP. The results indicate that human parietal association cortex exerts modulatory input to sensorimotor cortex, beginning at least 400 ms prior to movement. The differential effect on the NSs and MPs by parietal lesions suggests that these MRP components may have independent intracranial generators.

Acoustic Stimulation↗

PubMed2006

Intracerebral study of gamma oscillations in the human sensorimotor cortex.

Since few years, gamma oscillations have given rise to an increasing interest. They have been successively described as being involved in cognitive function and various sensory systems. However, their role remains the subject of much debate. Gamma rhythms are difficult to study in scalp recordings due to low amplitudes and because the skull filters out high-frequency signals. Hence, their study makes necessary intracerebral recordings. Here, we report our intracerebral data issuing from study of gamma oscillations in the human sensorimotor cortex during the preparation and execution of voluntary movements. These studies have been performed in epileptic patients explored by stereoelectroencephalography (SEEG). Whereas mu and beta rhythms reactivity was diffused, the gamma rhythm reactivity to the movement was very focused and was observed predominantly in the primary sensorimotor areas that were involved in the movement, as assessed by the electrical cortical stimulations. Gamma oscillations seemed to be related to the movement execution rather than to the movement preparation. We have compared the temporo-spatial relationships between movement-related cortical potentials (MRCPs) and sensorimotor rhythms. We show that (i) the late components of MRCPs (motor potential--MP and post-movement complex--PMc) and the gamma event-related synchronization (ERS) within the 40-60-Hz band always occurred in the same contacts (located in the primary sensorimotor areas) and (ii) the PMc peaked during the gamma ERS, whereas the MP began before it. The PMc, so-called 'Reafferent Potential', is supposed to reflect the somesthetic reafferentation of the sensorimotor cortex. Hence, it seems that the PMc and the gamma ERS represent two electrophysiological facets of the reafferentation of the cortex during the movement. We suggest that gamma oscillations within the 40-60-Hz band serve to facilitate kinesthesic afferences from the muscles and joints involved in the movement to the primary sensorimotor cortex, which would be necessary for controlling the ongoing movement.

Adolescent↗

PubMedDate not supplied

[Effect of strychnine on the neuronal reactivity of the sensorimotor cortex and the temporary connection in rabbits].

On awake nonimmobilized rabbits, evoked activity was studied of the sensorimotor cortex neurons in response to stimulation of the pyramidal tract, medial lemniscus and reticular nucleus of the midbrain tegmentum by stimuli of different frequencies, and driving reaction of cortical neurons to stimulation of these brain structures by series of stimuli of increasing frequency. Conditioned reflexes were also studied, established on the basis of combination of direct stimulation of the sensorimotor cortex and electrocutaneous stimulation. Application of the cortex of low concentration of strychnine solutions (less than 1%) heightened neurons reactivity and provides for the formation of temporary connection. Application of strychnine solutions of higher concentration (greater than 1%) led to opposite effects. Interconnection of electrical and behavioural effects is discussed.

Animals↗

PubMed2004

Structure of dependent relationships between neurons in the sensorimotor cortex of the left and right hemispheres in rabbits in immobilization catatonia.

Dependence in the activity of sensorimotor cortex neurons recorded simultaneously in the left and right hemispheres was detected in rabbits in baseline conditions, during the state of immobilization ("animal hypnosis"), and recovery of animals from this state. In baseline conditions, the total percentage of dependent relationships between close-lying (within 50 microm) neurons in the left hemisphere was significantly smaller than in the right hemisphere and did not change either in the state of immobilization or on recovery from it. The total percentage of dependent relationships between close-lying neurons in the right hemisphere decreased significantly during immobilization and returned to baseline levels on recovery from this state. The percentage of dependent relationships between distant (500 microm) neurons in immobilization, conversely, showed no change in the cortex of the right hemisphere, though it changed significantly in the cortex of the left hemisphere, returning to baseline values when the rabbits recovered from this state. Further analysis showed that this cortical interhemisphere asymmetry was based on the asymmetrical activity of individual neurons and small neuronal populations. Thus, changes in the structure of dependent relationships between neurons in microareas of the cortex of the left and macroareas of the cortex of the right hemisphere could be in different directions, while changes in microareas of the right hemisphere and macroareas of the left hemisphere were synergistic. Thus, asymmetry was detected at different levels of neuronal combinations (neuron pairs, micro- and macrogroups of neurons), which suggests mosaicism in neuron structure, which ultimately leads to overall functional asymmetry in "animal hypnosis." Some changes in the structure of dependent relationships between sensorimotor cortex neurons arising in "animal hypnosis" persisted or even became more marked after recovery of animals from this state.

Action Potentials↗

PubMed2005

Ultrastructure of the sensorimotor cortex of pubertal offspring of alcoholic male rats.

The ultrastructure of neurons, astrocytes, and capillaries in the sensorimotor cortex of three-month-old offspring of alcoholic male rats (8 g/kg of 50% alcohol solution daily for four weeks) was studied. Apart from signs of delayed maturation of nerve and glial cell processes, some cortical areas showed destructive changes affecting a proportion of neurons along with elements of compensatory-adaptive processes in some nerve cells. Membrane and myelin-like intranuclear inclusions and changes in the Golgi complex were characteristic features of the damage to populations of cortical neurons. Swelling of astrocytes, deformation of capillaries and changes in their ultrastructure, with accumulation of atypical inclusions in pericapillary astrocyte processes, degraded reciprocal exchange processes between blood and neurons. The possible role of the ischemic-hypoxic factor in delayed changes in the ultrastructure of the sensorimotor cortex in the offspring of alcoholic males is discussed.

Alcoholism↗

PubMed1999

Intramembranous structure of synaptic membranes with special reference to spinules in the rat sensorimotor cortex.

The intramembranous structure of the synaptic contact zone at presynaptic and postsynaptic membranes in the rat sensorimotor cortex was examined by means of the freeze-etching technique. In axospinous synapses, the synaptic contact zone is characterized by perforated and nonperforated aggregates of intramembranous particles at the extracellular half or E-face of the postsynaptic membrane. On some perforated synaptic contact zones, both synaptic membranes are marked by so called spinules. These invaginations of the postsynaptic membrane and the parallel presynaptic membrane into the axon terminal are situated at the particle free zones among the postsynaptic E-face intramembranous particle aggregates or in close proximity to it. Intramembranous characteristics of the spinules at both freeze-etched faces of presynaptic and postsynaptic membranes and their density of perforated axospinous synapses were analysed. The results are discussed in terms of plasticity at the synaptic contact zone of the axospinous synapses of the sensorimotor cortex in the rat.

Animals↗

PubMed1996

Structure of the synaptic junctions in the rat sensorimotor cortex. Freeze-etching study of axodendritic synapses.

The intramembranous structure of axodendritic synapses in the rat sensorimotor cortex was studied by means of freeze-etched replicas and thin sections. In thin sections, symmetric synaptic junctions were located on dendritic shafts. Examination of freeze-etched preparations supported the notion that the postsynaptic dendritic shaft membrane exhibited the same structure as the surrounding non-junctional membrane on both fracture faces. In thin sections, asymmetric perforated and non-perforated synapses were found on dendritic spines and dendritic shafts. In freeze-etched replicas, the postsynaptic membrane of the dendritic spine and some of the dendritic shaft synapses were characterized by perforated and non-perforated aggregates of intramembranous particles at the extracellular half (E-face). These aggregates are accepted as a freeze-etch equivalent of perforated and non-perforated asymmetric synapses seen in thin sections. The intramembranous characteristics of axodendritic synapses in the rat sensorimotor cortex are discussed in terms of synaptic contact zone plasticity.

Animals↗

PubMed1995

Dependence of sensorimotor cortex neuron activity on noradrenergic and serotoninergic transmission in unspecific thalamic nuclei.

Background and evoked impulse activity of sensorimotor cortex neurons and conditioned reflex of trained cats were changed by blockers of noradrenaline and serotonin receptors applied through chemitrodes to thalamic complex of the centrum medianum and nucleus parafascicularis neurons. Application of obzidan, an antagonist of beta-adrenoreceptor to the complex of the centrum medianum and nucleus parafascicularis induced an initial increase and following decrease of the motor activity of cats. After obzidan application conditioned reflex remained unchanged at the initial, excitatory phase and started to decrease later. Lisergamide applied to the complex of the centrum medianum and nucleus parafuscicularis produced an initial decrease of movement activity and then drowsiness of the animals. Responses to conditioned stimuli were gradually decreased. The background impulse activity of the sensorimotor cortex neurons increased after obzidan application and decreased rapidly after lisergamide injection into the complex of the centrum medianum and nucleus parafascicularis. The responses of cortical neurons to conditioned stimuli were reduced, sometimes completely eliminated in both cases. Background and evoked impulse activity greatly increased by application of 5-hydroxytryptamine after preliminary lisergamide-induced depression of the impulse activity. It was concluded that under natural conditions the noradrenergic system exerts indirect inhibitor effects on the neocortex neurons through the centrum medianum and nucleus parafascicularis thalamic complex, whereas the serotoninergic system acting via the same complex increases the background and evoked impulse activity of the sensorimotor cortical neurons.

Adrenergic Agents↗

PubMedDate not supplied

[The influence of BT-melanin on the recovery of conditioned instrumental reflexes in rats surviving after ablation of the sensorimotor cortex].

It has been shown the reinforcement of the corticofugal plasticity in adult rats after unilateral ablation of sensorimotor cortex accompanied by intramuscular injections of low concentrations of BT-melanin. In result the process of compensatory recovery in rats central nervous system is accelerated, confirmable by the rapid recovery of previously elaborated instrumental conditioned reflex in comparison with the control animals. It is assumed that the compensation of the motor deficit arised after the sensorimotor cortex ablation is ensured by the ability of two main motor systems of the brain (corticospinal and corticorubrospinal) to duplicate each other. This phenomenon of functional switching of descending influences has also been revealed in control group rats, not injected with BT-melanin. However the difference in time periods of operantly conditioned reflex recovery, for experimental and control groups, argues the apparent acceleration of this process, induced by the effects of BT-melanin. The obtained data considers the possibility of applied use of low concentrations of BT-melanin.

Animals↗

PubMed2002

Respiratory effects of sensorimotor cortex and their mechanisms in rats.

Acute experiments on anesthetized rats showed differential effect of various areas of the sensorimotor cortex on activity of the respiratory center. It is hypothesized that GABAergic structures of the solitary tract nucleus play an important role in the mechanisms of respiratory effects of the sensorimotor cortex.

Animals↗

PubMed1996

Presurgical identification of the primary sensorimotor cortex by functional magnetic resonance imaging.

The ability of functional magnetic resonance (MR) imaging to detect a selective sensorimotor cortex activation in healthy subjects and the feasibility of motor activation in patients with lesions around the central sulcus were investigated. Twenty-five healthy volunteers performed 100 motor activation trials, using a variety of motor tasks, which were monitored by several image analysis methods. The functional images were obtained using a 1.5-tesla standard MR imaging system magnet with blood oxygenation level-dependent contrast. Four patients were assessed using functional MR imaging and invasive cortical mapping. Rolandic cortex activation was observed in 98% of the trials performed on healthy subjects in which no head motion occurred. Nevertheless, the cortical response was not selective in a task-rest analysis due to concurrent activation of neighboring regions. Across-task comparison analyses were useful in cancelling nonrelevant activity in most cases (86%). In the patient group, the region identified as the sensorimotor cortex by invasive means corresponded accurately to the area that was activated in functional MR imaging. Present data support the feasibility of detecting selective activation of the rolandic cortex, even in the clinical setting, leading the authors to suggest the usefulness of this widely available technique in surgical planning.

Adult↗

PubMed2000

Enhanced behavioral recovery from sensorimotor cortex lesions after pyramidotomy in adult rats.

Unilateral transection of the bulbar pyramid, performed before the ablation of the ipsilateral sensorimotor cortex, has been shown to facilitate the recovery of operantly conditioned reflexes and compensatory processes in rats. Such enhanced behavioral recovery was absent when only the sensorimotor cortex was ablated. This phenomenon is explained by the switching of motor activity under the control of the cortico-rubrospinal system. Switching of the descending influences is accomplished through the following loop: cortico-rubral projection-red nucleus-inferior olive-cerebellum-thalamus-cerebral cortex. This suggests that a preliminary lesion of the peripheral part of the system, represented by a descending spinal projection, facilitates the recovery processes to develop during the subsequent destruction of its central part.

Animals↗

PubMed2002

Impulse activity of individual sensorimotor cortex neurons in rabbits after microiontophoretic administration of antibodies against acid fibroblast growth factor.

We studied the sensitivity of sensorimotor cortex neurons in rabbits to microiontophoretic administration of antibodies against acid fibroblast growth factor (anti-aFGF). Spontaneous activity and reaction of neurons to electrical stimulation of 'feeding centers' in the lateral hypothalamic area (LHA) were recorded. We analyzed impulse activity of 52 neurons in the sensorimotor cortex. It was shown that 14 neurons (25%) reacted to microiontophoresis of anti-aFGF (excitation and inhibition in 9 and 5 neurons, respectively). Microiontophoretic administration of anti-aFGF did not change the reaction (excitation or inhibition) of 27 neurons to electrical stimulation of LHA. Initially, 14 neurons did not response to LHA stimulation. After microiontophoretic administration of anti-aFGF, 6 of 14 neurons displayed pronounced reactions to electrical stimulation of LHA (excitation and inhibition in 2 and 4 neurons, respectively). These data suggest that aFGF plays an important physiological role in feeding motivations.

Journal Article↗

PubMed1995

Structure of the synaptic junctions in the rat sensorimotor cortex: freeze-etching study of neuronal gap junctions.

The membrane structure of neuronal gap junctions in the rat sensorimotor cortex was examined using freeze-etched replicas. The gap junction coupling was found between large, probably non-pyramidal neurons and dendrites, and was mostly associated with membrane specializations indicative of the contact zone of an asymmetric synapse or a puncta adhaerentia. The validity of freeze-etching method of identification and analysis of neuronal gap junctions as a feature of the synaptic organization in the rat sensorimotor cortex is discussed.

Animals↗

PubMedDate not supplied

The role of the cholinergic system of the sensorimotor cortex of the rat brain in controlling different types of movement.

The role of the cholinergic system of the sensorimotor cortex of the Wistar rat brain in controlling various types of movements was assessed by studying the effects of microinjections of carbachol and scopolamine into the representation area of the forelimb on the performance of two types of fore-limb food-procuring movements--with and without pressure on an obstacle--as well as on the animals' locomotion. These studies showed that administration of the cholinergic agonist carbachol (0.03-3 microg) leads to slowing of both types of procuring movements and acceleration of locomotor activity in an open field. Injections of the cholinergic antagonist scopolamine (0.3-3 microg) into the same area accelerated procuring movements, while the animals' locomotor activity remained unaltered. These data indicate that the cholinergic system of the sensorimotor cortex has different regulatory influences on movement activity (locomotion) and the performance of learned movements requiring forelimb muscle tone to be maintained for different periods of time (the usual rapid movements used for extracting food from a narrow horizontal tube versus slow movements with additional tactile and tonic components).

Animals↗

PubMed1999

Motor dysfunction and sensorimotor cortex activation changes in schizophrenia: A study with functional magnetic resonance imaging.

Recent studies demonstrate a diminished activation of the sensorimotor cortex and supplementary motor area (SMA) in schizophrenia which may be involved in the pathogenesis of neurological soft signs (NSS). Yet, the question whether a retarded motor performance may account for these changes remained to be clarified. Twelve DSM-III-R schizophrenics and 12 healthy controls were included. All subjects were right-handed. Nine patients received clozapine, two conventional neuroleptics, and one was drug-free. Functional magnetic resonance imaging (fMRI) was obtained in a resting condition and during pronation/supination at three speed levels (low, medium, and high) with motor performance recorded simultaneously using a pronation/supination device. While measures of motor retardation (i.e., repetition rate and amplitude of the movements) did not differ between patients and controls, the variability of performance was significantly (P < 0.05) increased in the patients' group. In addition, patients with schizophrenia showed a significantly (P < 0.05) decreased activation of the sensorimotor cortices. Similar, although nonsignificant (P = 0.09) activation changes were observed in the SMA. Activation differences were more pronounced at a slow speed and in the drug-free patient. These results confirm a diminished sensorimotor cortex and SMA activation and indicate that variability of performance rather than retarded performance per se may correspond to these changes.

Adult↗