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S N Raeva

Publications and source records attributed to S N Raeva.

At least 37 records · Page 2Linked to original sources
PubMedDate not supplied

Changes in the spike activity of neurons in the ventrolateral nucleus of the thalamus in humans during performance of a voluntary movement.

The responses of neurons in the ventrolateral nucleus (VL) of the thalamus were studied in humans during performance of voluntary motor tests; recordings were made with microelectrodes during stereotaxic operations in patients with Parkinson's disease. Two previously classified types of polyvalent neurons (A, B) were found to show different patterns of responses during the functional stages of carrying out a voluntary movement (preparation, initiation, performance). A and B neurons showed concordant changes in the dynamics of ongoing network activity in the form of linked (activation-inhibition) and synergic (activation) response patterns, correlating with the preparation-trigger and performance phases of movements. It is suggested that the simultaneous activity of both types of neuron, with their common functional nature, reflects integrative processes occurring in the ventrolateral nucleus and associated with programming and processing of general signal parameters but not with the performance of any particular movement. The anterior (Voa nucleus) and posterior (Vop) parts of the ventrolateral nucleus were found to have different roles in organizing voluntary movements, associated with differences in their cellular organization and mechanisms of transmitting motor signals. It is suggested that the concordant changes in the activities of the two types of neurons in these areas seen during the performance of voluntary movements gives the ventrolateral nucleus a key role in the motor control system in humans.

Electromyography↗
PubMedDate not supplied

Features of the spike activity of globus pallidus neurons and pallido-thalamic functional interactions during targeted verbally cued movements in humans.

This paper reports the results of an analysis of evoked spike activity in neurons of the human globus pallidus during performance of a targeted verbally cued movement, along with a comparison with the results of previous experiments on evoked spike activity of neurons in the reticular and ventrolateral thalamic nuclei in an identical test, recorded during stereotaxic surgery with a microelectrode technique in patients with Parkinson's disease. The following observations are reported for the first time: 1) The existence in the outer segment of the human pallidus of neurons with convergent properties, selectively responding with activation to significant "stimulatory" verbal command stimuli initiating the launch and performance of a targeted movement; 2) similarity in the dynamics of concordantly occurring responses of convergent neurons in the integrative centers of the striopallidothalamic circuit in functionally important phases of movement act performance. It is suggested that the similar concordantly developing dynamics of neuronal rearrangements during the performance of a targeted movement act within the structures of this circuit reflects functional interstructural and interneuronal interactions occurring in the striopallidothalamocortical system of the human brain, which is involved in organizing verbally cued targeted forms of activity.

Cues↗
PubMedDate not supplied

Spontaneous activity of individual neurons in the human ventrolateral thalamus during changes in the functional state of the brain.

Background spike activity of 235 cells of the integrative subcortical motor center, i.e., the ventrolateral nucleus of the thalamus, were analyzed in nonanesthetized human brains during stereotaxic surgery in patients with various forms of Parkinson's disease. Previous data on the existence of two major types of neurons with convergent properties in the ventrolateral nucleus were confirmed. These cell types are: 1) cells with irregular occasional activity, with a tendency for spikes to group into the frequency ranges 5 +/- 1 and 10-30 Hz (type A cells, 74%), and 2) cells with constant rhythmic (3-6 Hz) generation of short volleys of discharges, with an interval structure similar to that of low-threshold Ca(2+)-dependent volley activity (type B, 26%). This is the first report demonstrating that changes in the functional state of the brain (after repeated movement trials, in transient anesthesia) are accompanied by transiently occurring transformations of the initial irregular activity of A cells into a rhythmic, volley-like pattern whose interval structure was in some cases similar to the spike activity of B cells. Differences in the localizations of A and B neurons in the ventrolateral nucleus are described, along with differences in the correlation characteristics of their background spike activity with the pathological features of Parkinson's disease (tremor, rigidity). The nature of the two types of convergent neurons in the ventrolateral nucleus is discussed, and a basis is laid for the importance of the functional factor in understanding the transformation of their background spike activity, due to the properties of cell membranes and intercellular and interstructure interactions in conditions of the living nonanesthetized human brain.

Brain↗
PubMedDate not supplied

[Electromyography in patients with spastic torticollis].

The article describes the results of electromyographic examination of the muscles of the neck in 26 patients with spasmodic torticollis. Electromyography was performed before and after stereotaxic operative interventions on the nucleus of Cajal or in combination with the diencephalic structures. It is shown that electromyographic examination of patients, especially with the use of functional motor and oculomotor tests, widens essentially the possibilities of the diagnosis by facilitating the identification or specification of the predominantly involved group of muscles. The discovery of concurrent oculographic and electromyographic changes in the dominant muscles of the neck during oculomotor tests is evidence of the connection of the system of concurrent movements of the eyes and head with the motor systems participating in the pathology of torticollis. Analysis of the dynamics of electromyographic changes in patients with predominance of the tonic component in the early and late postoperative periods is indicative of gradual increase of positive changes in the motor sphere, which, evidently, is due to the dynamic reorganizations in the previously formed stable pathological system.

Action Potentials↗
PubMedDate not supplied

[Identification of nuclei of the pretectal area during stereotaxic surgery for spastic torticollis].

The neurons of mesencephalic nuclear structures were studied by microelectrode techniques for functional identification of the interstitial nucleus of Cajal during 18 stereotaxic operations on patients with torticollis. It is shown that the use of microneuronography for functional identification of structures of the pretectal region and mesencephalic structures bordering it is promising. The functional cellular complexes of these structures which respond selectively to voluntary movements of the eyes and head, rapid voluntary movements of the eyes, fixation and maintenance of the gaze, and combined movements of the eyes and head are characterized for the first time. In comparison with intracerebral radiological guiding points, the registration of these data makes possible intraoperative active search for functional neuronographically identified zones linked with the pathological mechanisms of torticollis and the performance of selective destruction with minimum volume of damage.

Adolescent↗