EVOKED AND SPONTANEOUS ACTIVITY IN SINGLE UNITS OF MEDIAL BRAIN STEM DURING NATURAL SLEEP AND WAKING

Abstract

Recordings from single brain stem units of unrestrained, unanesthetized cats were obtained during quiet waking, sleep with eeg slow waves, and sleep with low voltage fast eeg activity. Many of the units showed depression of evoked discharge during sleep. This depression was most marked during sleep with low voltage fast eeg activity. There was a significant positive correlation between response latency and depression of click responses during sleep. In contrast to evoked activity, spontaneous discharge rates were greater during sleep with slow waves than during waking in about two-thirds of the units. Very rapid spontaneous firing, with mean rates up to 50 spikes/sec, was observed during sleep with low voltage fast eeg activity. These results suggest that occlusion may play a role in the depression of evoked activity of brain stem units during sleep.