The relationship between cortical recruiting responses and ponto-geniculo-occipital waves during paradoxical sleep in the cat.

In an earlier study it was found that during paradoxical sleep (PS) thalamo-cortical recruiting responses (RRs) and rapid eye movements usually did not appear simultaneously. As shown elsewhere, ponto-geniculo-occipital (PGO) wave activity and rapid eye movements are during PS closely related to each other in time. Similarly, in the present study it was observed that during paradoxical sleep in cats in which the center median nucleus of the thalamus was being stimulated at a rate of 7--9 Hz PGO waves in the geniculate nuclei did not in the rule occur in the presence of RRs recorded from the motor cortex. This effect was most pronounced with respect to series of PGO waves which usually occur at a rate of 4--7 Hz. On the basis of these experiments it was concluded that PGO waves and RRs are reciprocal events and mutually exclusive. Considering to the well-known fact that RRs represent synchronization, this negative correlation between RRs and PGO waves indicates that the desynchronizing tendency typical to paradoxical sleep is most pronounced during the occurrence of PGO waves.