The effects of varying stimulus intensity on P300 during REM sleep

EVENT-RELATED potentials (ERPs) are often used to measure the extent of inf ormation processing during sleep. Previous studies have indicated that a la te positive wave, P300, can be elicited during REM sleep if stimuli are ver y rare and/or very loud. The present study examined the role of stimulus in tensity in eliciting a P300 during REM sleep. Eight subjects were presented with auditory tone pips with an intensity of either 0, 60, 80 or 100 dB SP L. Stimuli were delivered at random with equal probability. Trials were sor ted by stage of sleep, stimulus intensity, and presence or absence of rapid eye movements in REM sleep. During the waking state, when subjects read a book, the loud 100 dB stimulus elicited short (P3a) and long latency (P300) positive waves (peaking at 293 and 373 ms respectively). In stage of 2 non -REM sleep, N1 decreased to baseline level while P2 increased in amplitude compared to the waking state. A P300 could not be observed in stage 2 sleep regardless of the level of stimulus intensity. During REM sleep, a late P3 00 (latency 363 ms) was elicited by the 100 dB stimulus. The earlier positi ve peak (i.e. P3a) was not apparent. The P300 was reduced in amplitude comp ared to the waking state. Its amplitude did not differ between phasic and t onic states of REM sleep. A late parietal negative slow wave (SW) was also apparent during REM. Although the SW was larger during phasic compared to t onic REM, the difference was not significant. These data suggest that stimu li which are sufficiently intrusive to elicit a P300 in the waking state co ntinue to do so in REM sleep. NeuroReport 10:2313-2318 (C) 1999 Lippincott Williams & Wilkins.