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Biomedical subjects

S P Narikashvili

Publications and source records attributed to S P Narikashvili.

At least 19 recordsLinked to original sources
PubMed1986

[Relation between sleep and processes of retention and mental activity].

The structure of nocturnal sleep was studied in two groups of subjects: the group I subjects had been given 60 unfamiliar English words to learn, whereas Group II subjects had been playing games of chess. The paradoxical sleep (PS) latency in the 1 st cycle, the type of falling into the PS, and intensity of rapid eye movements were recorded. No reliable difference was found in the sleep structure of both test groups. No correlation either was observed between the sleep characteristics and the quality of memorizing the verbal material.

Adult↗
PubMed1981

[Neuronal activity of cat thalamus reticular and relay nuclei].

The interaction between the unit activity of the thalamic reticular and relay nuclei was investigated on cats immobilized with tubarine. It was shown that unit activity of the relay nuclei can be significantly modulated by stimulation of the n. reticul. By simultaneous recording (with two microelectrodes) of the activity of thalamic reticular neurons the relay unit activity can be suppressed; during peripheral and cortical stimulations the alternation of excitation-inhibition of the thalamic reticular and relay units can be observed; excitation of thalamic reticular units can be associated with excitation of the relay nuclei units. Such types of interaction may also exist during simultaneous recording (by two microelectrodes) of the activity of the relay units and putative interneurons. Sometimes IPSPs with short latency (1 ms) were evoked in the thalamic relay nuclei during thalamic reticular stimulation. The existence of direct monosynaptic inhibition of the relay unit activity by the thalamic reticular units as well as inhibition by the activation of the putative interneurons of the specific thalamic nuclei is suggested.

Animals↗
PubMed1977

[Interaction between spindles evoked by electric stimulation of different regions of the cerebral cortex].

In unanesthetized immobilized cats, under repeated administration of small doses of nembutal (2-3 mg/kg), connections between the projection and the parietal associatition cortical areas was studied as well as the interaction between spindles elicited by stimulation of these areas. Stimulation of the primary sensory areas (auditory or somatosensory) was shown to be able to elicit spindles not only in the stimulated area but in the association cortex too. This latter spindle, being kind of induced from the sensory areas, interacts with the spindles elicited by the direct electrical stimulation on the association cortex.

Anesthesia, General↗
PubMed1975

[Findings and reflections on the reverberation of thalamocortical impulses].

Chang's experiments showing the rhythmic afterdischarge in slightly nembutalized cats which he considered as a manifestation of the activity of thalamocortical reverberating circuits, prompted us to study the origin of the afterdischarge in the auditory cortex arising in response to single sound clicks on unanesthetized immobilized and nembutalized cats. The rhythmic afterdischarge was found to be most pronounced at light anesthesia with a tendency of background activity to synchronization, which may be evidenced by rare bursts of spindles. During the prolonged spontaneous desynchronization as well as during stimulation of mesencephalic reticular formation no rhythmic afterdischarge and no spontaneous bursts of spindles arose. With a deepening of anesthesia slow afterdischarge undergoes precisely the same changes as spontaneous spindle bursts (the duration tends to increase for a while with a subsequent decrease, the frequency and then the amplitude of waves decrease and eventually they disappear altogether). These and other findings suggest that rhythmic afterdischarge of the auditory cortex arising to sound clicks seems to be similar to the evoked spindle in response to peripheral and central stimulations. It was reported in many previous and recent papers. The fact, that following the cooling or ablation of the auditory cortex the rhythmic afterdischarge to sound clicks as well as spontaneous spindle bursts keep arising in the medial geniculate body without changing their patterns, militates also against the possibility of thalamocortical reverberation.

Animals↗