Evidence for the presence of eye movement potentials during paradoxical sleep in cats

1. Phasic activities related to eye movements in the dark in abducens nucleus (N.VI), lateral geniculate body (LGB), visual cortex, and lateral rectus muscle were analyzed in 18 cats with chronically implanted electrodes during waking and sleeping. 2. N.VI waves, both during waking and sleeping, were multiphasic, and two distinct wave forms were noticed on either side of the pons. The N.VI waves preceded each ocular movement by 10--20 msec. 3. Both during waking and paradoxical sleep (PS), N.VI waves always preceded those occurring in the LGB. During waking, eye movement potentials (EMPs) in LGB followed the onset of the N.VI wave with a long (greater than 60 msec) and variable latency, but followed the end of the same wave with a rather constant delay (about 20 msec). During PS, two distinct populations of latency were observed between onset of the pontine waves and that of LGB waves. The latency of one population was less than 35 msec, and of the other more than 66 msec. 4. Since the LGB waves following N.VI waves with a long latency were similar in a number of respects to EMPs during wakefulness (EMPw), they were judged to be EMPs (EMPps), and were distinguished from LGB PGO waves, which followed N.VI waves with a short latency. Cortical EMPps were observed as well, but occurred about 8--10 times less frequently than the PGO wave. 5. In the light of the present results, the mechanisms responsible for EMP and PGO wave activities are discussed.