Electroconvulsive shock: Effects on sleep and cortical steady potential in the rat

Continuous ECoG, EMG and SP recordings were taken in rats prior and subsequent to ECS treatments. Slow-potential (SP) shifts associated with sleep and wakefulness were consistent in direction and predictable in occurrence before and after treatment. SP shifts accompanying the transition from quiet wakefulness to slow-wave sleep (SWS) and from SWS to paradoxical sleep (PS) were surface negative. Upon arousal, there was a positive shift to waking SP levels. A substantial increase in total sleep time (TST) accompanied by a reduction in PS persisted for 3 days following ECS. Thereafter, both TST and PS returned to baseline levels. A rebound in PS duration and frequency occurred at different times in different animals, but a significant overall rebound effect could not be demonstrated in the pooled data. All treatments elicited grand mal electrical and behavioral seizures. ECS-induced SP shifts were surface negative (4–8 mV) and lasted from 10–30 sec. In contrast to the SP stability prior to ECS, every animal underwent major aperiodic SP shifts after ECS. These were of greater magnitude and longer duration than those seen during pre-ECS sleep-wakefulness cycles.