PubMed Health⌕ Search

Biomedical subjects

N D Lortkipanidze

Publications and source records attributed to N D Lortkipanidze.

6 recordsLinked to original sources
PubMed1988

[Neurophysiological analysis of the effects of selective deprivation of paradoxical sleep].

Neurophysiological analysis of the effects of selective and total paradoxical sleep deprivation (PSD) involving the replacement of paradoxical sleep (PS) phases by equivalent (as to duration) episodes of wakefulness is carried out. In contrast to the "classical" method of momentary awakening of the animal, a new method does not lead to: (1) the accumulation of PS need associated with more frequent PS onsets during deprivation; (2) PS rebound in a postdeprivation period; (3) dissociation of PS components, i.e. their occasional occurrence in other phases of the sleep-wakefulness cycle due to the phenomenon of self-deprivation; (4) increase in the rate of pontogeniculo-occipital (PGO) spikes, eye movements and heart rate during PS phases in the postdeprivation period. The application of selective and total PSD techniques caused no noticeable changes in the functional state and integrative activity of the brain, the latter warranting its successful use for treatment of some psychoneurological disturbances in clinics. The assumption has been advanced about the similarity of the neurochemical changes forming the need both for wakefulness and PS.

Animals↗
PubMed1984

Some aspects of conditioned reflex activity during sleep.

Acquisition, retrieval and extinction of instrumental alimentary reflexes during various types of sleep was studied in cats with metallic electrodes chronically implanted in different brain structures. The possible acquisition and extinction of a defensive conditioned reflex with the onset of paradoxical sleep (PS) serving as a conditioned signal and painful electrical stimulation of the skin as unconditioned was investigated. Results suggest that: (i) in the presence of a high food motivation the conditioned signals delivered during sleep cause the retrieval of previously acquired instrumental alimentary reflexes, and in PS the brain is capable of discriminating conditioned signals more accurately than during slow wave sleep, (ii) after a conditioned reaction to one of two conditioned signals is extinguished through non- reinforcement, the second signal remains effective, causing an instrumental alimentary reflex, (iii) the extinction of instrumental alimentary reflexes effected during sleep is not retained after the animal's awakening, whereas the extinction of a defensive conditioned reflex is retained, (iv) PS may serve as an endogenous conditioned signal during the acquisition of a defensive conditioned reflex. Thus motivational processes developing during PS are effective endogenous stimuli eliciting past experience dreams.

Animals↗
PubMedDate not supplied

[Self-deprivation of paradoxical sleep in cats].

The phenomenon of paradoxical sleep (PS) self-deprivation has been detected and described. The self-deprivation is acquired just as a classical conditioned reflex during enforced PS deprivation both by water tank procedure and by the animal's awakenings in response to sensory stimuli or direct electric stimulation of activating structures of the midbrain and diencephalon, following the transition of slow-wave sleep to PS. In this situation the transition of the brain from one physiological state to another is a conditioned signal, and sensory stimulation or brain stimulation, resulting in arousal reaction, serves as an unconditioned stimulus. It is suggested that the detection and analysis of PS self-deprivation are of a great importance, on the one hand, for correct understanding of the functional significance of this physiological brain state, and, on the other hand, for accurate analysis and assessment of the dissociative processes, observed during PS deprivation and postdeprivation period.

Animals↗
PubMedDate not supplied

[Interdependence of learning and paradoxical sleep in the cat].

The effect of learning sessions on the structure of the sleep-wakefulness cycle, as well as the effect of paradoxical sleep (PS) deprivation (PSD) following learning sessions, on the acquisition and extinction of instrumental alimentary reflexes to two feeders with sound discrimination, were studied on cats. The analysis of the data obtained led to following conclusions: The above learning sessions have no marked effect on the structure of the sleep-wakefulness cycle in the post-learning period, i.e. the percentage ratio of its phases is not altered by the increase of one of them. When PSD by non-emotional awakening is used, the number of PS onsets is not affected by learning sessions. This indicates that learning does not produce any considerable effect on the formation of PS need. PSD by non-emotional awakening following learning sessions does not retard the acquisition and extinction of the instrumental alimentary reflexes. The above data are interpreted as indicating that PS has no specific significance in memory trace consolidation during formation of long-term memory.

Animals↗