Sleep alterations following total cerebellectomy in cats.

Polygraphic sleep studies were conducted in six cats just before cerebellectomy and 3 and 10 days after the operation. These studies were continued in the four surviving animals 30, 100, 200, 300, and 315 days days post-operatively. The findings confirmed the existence of two postoperative phases correlated with the degeneration of brainstem structures: an initial period (day 3) was characterized by a significant increase in wakefulness; a second, later period (days 10 and 30) was distinguished by numerous slow waves and sleep spindles in the electrocorticogram. There was a stable increase in the amplitude and density of rapid eye movements, perhaps reflecting the ataxia evident during the waking state after cerebellectomy. At day 3, there was a significant decrease in the duration of paradoxical sleep (PS) periods, followed by a significant increase at day 10 that continued to the end of the study. The number of PS states tended to decrease and the PS latency tended to increase in the long-term survivors. All other sleep parameters appeared to normalize by day 100. These findings suggest that the cerebellum plays a modulatory role with respect to the pontine structures responsible for the generation of phasic activity during PS.