Effects of REMs and PGOs on visual evoked responses during paradoxical sleep of cats.

The amplitude modifications of VERs from paired geniculate stimuli during paradoxical sleep were studied in five cats with chronically implanted electrodes, in the presence of REMs and during PGOs without REMs. In both cases the C5 component of evoked potentials was significantly enhanced with respect to the controls. This facilitation affecting presumably only the postsynaptic component of the response seems linked to signals reaching the visual cortex through other than geniculo-striate pathways. The disinhibition of the second VER appears to be due to intracortical mechanisms, and is not specifically related to phasic events of sleep, such as we previously described during light conditioning and in the absence of eye movements. It is proposed that this effect may be a more general phenomenon caused by changes in cortical activation during eye movement and conditioning.