[The role of the medial preoptic area in the organization of paradoxical sleep]. / Rol' medial'noi preopticheskoi oblasti gipotalamusa v organizatsii paradoksal'noi fazy sna.

Influence of electrical stimulation of the medial preoptic area of cats on characteristics of paradoxical sleep and activity of medial preoptic neurons were studied in the course of sleep-waking cycle. Low-frequency stimulation of this structure in the state of slow-wave sleep evoked short-latency electrocortical desynchronization and induced transition to paradoxical sleep or paradocical sleep-like state. The same stimulation during the whole period of paradoxical sleep results in a reduction of its duration, practically complete disappearance of tonic stage, and increase in the density of rapid eye movements in phasic stage. The vast majority of meurons in the medial preoptic area decreased their firing rates during quiet waking and slow-wave sleep and dramatically increased their activity during paradoxical sleep. More than 50% of such neurons displayed activation 20-70 s prior to the appearance of electrocorticographic correlates of paradoxical sleep. Some neurons were selectively active during paradoxical sleep. Approximately 50% of cells increased their firing rates a few seconds prior to and/or during series of rapid eye movements. The results suggest that the medial preoptic area contains the units of the executive system (network) of paradoxical sleep and are involved in the mechanisms of neocortical desynchronization.

[Dynamics of neuronal activity in the lateral preoptic area of hypothalamus in the course of sleep-waking cycle]. / Dinamika aktivnosti neironov lateral'noi preopticheskoi oblasti gipotalamusa v tsikle bodrstvovanie-son.

Frequency and patterns of activity of 106 neurons in the lateral preoptic area of unanesthetized cats were studied under conditions of indolent head fixation. It was shown that this structure contains two somnogenic neuronal populations with different functions. Neurons increasing their discharge frequency during transition from active to quiet wakefulness and subsequent sleep development to the point of phasic stage of paradoxical sleep development are considered as elements of an anti-waking system, which is involved in the mechanisms of sleep onset and deepening by means of inactivation of the arousal system. Neurons displaying the highest firing rates during light slow-wave sleep and synchronization of discharges with sleep spindles are considered as elements of a slow-wave sleep network.

[Impulse activity of neurons in the nucleus pontis oralis in cats during sleep--wakefulness cycle]. / Dinamika impul'snoi aktivnosti neironov oral'nogo iadra mosta v tsikle bodrstvovanie--son u koshek.

The nucleus pontis oralis contains several populations of neurons showing distinct sleep-waking discharge patterns. PS-on, PS-off cells, and neurons that discharged in association with phasic movements during paradoxical sleep and/or waking, were found. The findings suggest that different populations of the nucleus pontis oralis neurons take a distinct part in paradoxical sleep control.

[The role of the posterior hypothalamus in the regulation of paradoxical sleep]. / Rol' zadnego gipotalamusa v reguliatsii paradoksal'noi fazy sna.

Posterior hypothalamus was found to take part in the inhibitory control of the paradoxical sleep executive mechanisms responsible for the ECoG desynchronisation and phasic events. Functional activity of the posterior hypothalamus seems to be at its lowest during the paradoxical sleep stage as characterised by phasic events and the ECoG desynchronisation, and increases during the stage with alpha-like activity in the ECoG and absence of phasic events, the latter having, probably, a "sentinel" function.