CHARACTERIZATION OF TRANSITION SLEEP EPISODES IN BASE-LINE EEG RECORDINGS OF ADULT-RATS

By scoring 5-s EEG epochs and calculating spectral power of consecutiv e EEG segments as short as 1 s, transition sleep (TS) episodes were id entified in baseline recordings of adult rats. TS episodes were charac terized by the abrupt appearance of theta and alpha waves within an on going period of slow-wave sleep (SS). They were followed by paradoxica l sleep (PS) or, somewhat more frequently, by a period of wakefulness (W) that often led to an additional SS. Statistical values of the main variables of TS --> (W) and TS --> (PS) episodes are presented, toget her with comparable data concerning previous SS and following W or PS episodes. On the whole, TS episodes were more numerous than PS episode s, and less numerous than SS episodes. Their average duration was cons iderably shorter. As a consequence of the identification of TS and of brief W or PS epochs intervening within SS, the number of SS episodes was estimated to be considerably higher than previously assessed, and their average duration considerably shorter. Copyright (C) 1996 Elsevi er Science Inc.