Discharge patterns of single geniculate neurons during the rapid eye movements of sleep.

SEVERAL RECENT STUDIES HAVE SHOWN that sleep with EEG slow waves is periodically interrupted by brief episodes of sleep with low-voltage fast EEG activity and rapid eye movements (REMs) (7, 8, 18, 19). During these episodes, single waves or groups of two to three waves appear in the lateral geniculate body in association with the REMs (6, 21). Each wave has an amplitude of 100-200 pV., a duration of about 150 msec., and is predominantly monophasic (6). During sleep with REMs the monophasic waves appear synchronously in both geniculates (3, 23). It has recently been found that depolarization of optic tract terminals lasting about 150-200 msec. OCcurs during the monophasic geniculate waves (2, 17). Thus, the REMs of sleep are associated both with a change in polarization of optic tract terminals and with a monophasic wave in the lateral geniculate. The present experiment was performed in order to study the discharge of geniculate neurons while these two events are taking place. The findings indicate that the majority of geniculate neurons fire impulses in bursts during REM sleep and that the monophasic wave appearing in the lateral geniculate during the REM is correlated with this unitary discharge. These findings were obtained both in intact cats and in cats whose eyes had been enucleated.