[Dynamics of the neuronal activity of midbrain reticular nuclei in the sleep-wakefulness cycle].

Dynamics of neuronal activity of the mesencephalic reticular nuclei (n. cuneiformis, n. parabrachialis) in the sleep-wakefulness cycle was studied in free moving rats using mobile metallic microelectrodes. Computer analysis and statistical treatment of data have shown that the majority of neurons in the above-mentioned reticular nuclei of the mesencephalon (76% and 66%, respectively) generate with high frequencies during active wakefulness and emotional stage of paradoxical sleep; the frequency of discharges is less during passive wakefulness and nonemotional stage of paradoxical sleep, while in the slow-wave sleep they exhibit the least activity. Comparatively small number of neurons (24%, 15%) show inverse dynamics of activity. They fire more intensively during slow wave sleep and the frequency of discharges decreases during active wakefulness and emotional stage of paradoxical sleep. During quiet wakefulness and nonemotional stage of paradoxical sleep the neuronal activity attains the level observed in a slow-wave sleep. In n. parabrachialis some neurons are found which fire intensively during active wakefulness, the frequency of their discharges decreases in passive wakefulness and slow-wave sleep and is the least in paradoxical sleep. The similarity and difference of the neurophysiological mechanisms of phases and stages of the sleep-wakefulness cycle are discussed.