[Effect of deprivation of paradoxical sleep on retention of the "passive" avoidance response]. / Vliianie deprivatsii paradoksal'nogo sna na sokhranenie reaktsii "passivnogo" izbeganiia.

The effect of paradoxical sleep deprivation on the retention of passive avoidance was studied in rats. The analysis of the data obtained shows that paradoxical sleep deprivation produces impairment of the criterian of passive avoidance retention, latency prolongation of this reaction and augmentation of rat's motor activity in open field. It may be suggested that impairment of the criterion might be due to enhancement of motor activity, rather than to deprivation of paradoxical sleep per se.

[The role of synchronized electric activity in the development of epileptiform discharges]. / Znachenie sinkhronizirovannoi élektricheskoi aktivnosti v vozniknovenii épileptiformnykh razriadov.

The possibility of production of the epileptiform discharges throughout the sleep--wakefulness cycle was studied by means of thresholds for isolated EEG epileptiform discharges in cats. The experiments with artificially induced EEG synchronization (nembutal) indicate that the EEG synchronization does not facilitate the epileptiform discharges. However, this fact does not include the well--known standpoint concerning the preferential role of the EEG synchronization in provoking generalized seizures.

[Effect of paradoxical sleep deprivation on elaboration and differentiation of alimentary conditioned reflexes]. / Vliianie deprivatsii paradoksal'nogo sna na vyrabotku i differentsiatsiiu pishchevykh uslovnykh refleksov.

Paradoxical sleep deprivation of cats by means of awakening them without any significant emotional stress does not affect the acquisition of sound discrimination. Paradoxical sleep deprivation by Jouvet's method producing emotional stress impairs the acquisition of sound discrimination. However, it fails to affect the reproduction of preliminary elaborated sound discrimination.

Effect of experimentally induced generalized seizures on the wakefulness--sleep cycle.

The effect of experimentally induced generalized seizures on the relations between the various phases of sleep in the wakefulness--sleep cycle was studied in cats with chronically implanted electrodes. After generalized convulsions induced by electrical stimulation of the dorsal hippocampus, unlike those of amygdalar origin, clearly defined changes were observed in the structure of the wakefulness--sleep cycle. In the postseizure period, with increasing wakefulness sharp depression of paradoxical sleep takes place. However, in slow wave sleep only slight changes were observed. Instead of a rebound phenomenon, paradoxical sleep was sharply induced in cats after preliminary deprivation of paradoxical sleep as a result of generalized seizures induced by electrical stimulation of the neocortex. Nonspecific hyperactivation of the brain, in the form of epileptiform discharges, thus has a particularly marked effect on the structure of paradoxical sleep.

[Effect of experimentally induced generalized convulsions on the sleep-wakefulness cycle]. / Vliianie éksperimental'no vyzbannykh generalizovannykh sudorog na tsikl bodrstvovanie--son.

Electrical stimulation of the dorsal hippocampus appeared to have obvious effect on the ratio of phases of the wakefulness--sleep cycle: during the postconvulsive period when wakefulness is prolonged, paradoxical sleep is sharply decreased, while the slow wave sleep changes are insignificant. However, this effect is less pronounced after generalized seizures evoked by amygdaloid stimulation. Thus unspecific hyperactivation of the brain during experimentally induced generalized seizures exert an acute effect on the paradoxical sleep shortening its duration. This emphasized the functional significance of paradoxical sleep that might be a periodical increase of the brain activity during sleep.

Effects of electrical stimulation of the mesencephalon and diencephalon on the paradoxical phase of sleep.

During paradoxical sleep electrical stimulation of the mesencephalic reticular formation and emotiogenic structures in the mesencephalon and diencephalon produced depression or an increase in the theta rhythm of the hippocampal and entorhinal electrical activity. However, stimulation not involving behavioral arousal did not cause a transition from paradoxical phase into slow wave sleep. The cessation of stimulation restored the normal structure of the paradoxical phase. Stimulation of the reticular formation causing the depression of the hippocampal and entorhinal theta rhythm without behavioral arousal did not affect duration of the paradoxical phase, which was shortened, however, by electrical stimulation of the emotiogenic structures evoking an increase in the hippocampal and entorhinal theta rhythms. Stimulation of ventromedial hypothalamus or septum (during wakefulness inhibiting motivational behavior and emotional stress) caused transition from the paradoxical into slow wave sleep. This is probably caused by a decrease in emotiogenic stress, which during the paradoxical phase is usually on a high level.

Electrical activity of the hippocampus during delayed responses and hypothalamic stimulation in the cat.

Electrical activity of hippocampus was investigated in cats in the delayed response situation by comparing spectral analysis and integration of electrohippocampogram rhythms in different stages of delayed response performance. In addition, electrical stimulation of lateral and ventromedial hypothalamic nuclei was used to observe changes in the hippocampal theta rhythm, as well as the behavioral effect during the delayed response performance. It is concluded that changes in the hippocampal theta rhythm are related to the changes in the drive level: high drive results in increasing the theta rhythm, whereas drive reduction results in its suppression. The activating role of hypothalamus in the dynamic changes occurring in the limbic circuit and their function in solving the delayed response problem are widely discussed.

Effects of cingulate cortex lesions on emotional behavior and delayed responses in cats.

Bilateral thermocoagulation of the cingulate gyri produced an abolishment of fear reactions concomitantly with an exaggerated aggressiveness and a drastic impairment of delayed responses. The changes in emotionality subsided after several months but there was no recovery, even after prolonged post-operative training, of the dalayed responses with a 5 min delay. Only partial improvement of the responses with shorter delays (10 sec and 1 min) was observed. This memory deficit is discussed in terms of disruption of neuronal limbic circuits necessary for maintaining the impulse reverberation.