During experiments conducted on albino rats the deficiency of passive avoidance retention was shown to correlate not only with the reduction in REM sleep and SWS, but also with disappearance of phasic component of theta-rhythm. Drugs with nootropic mode of action (cleregyl, centrophenoxin, antioxidant 3-xypyridine) recovered the deficiency of passive avoidance retention and increased phasic component of theta-Rhythm, while phenazepam enhanced tonic component of theta-rhythm, and failed to act upon learning deficits. It seems likely from these results that the electrophysiological correlates of antiamnestic effect is the maintenance of proper two-component theta-rhythm and the increase in its phasic component, whereas the destructuring of sleep, including REM sleep reduction is not considered to be key determinant in the action upon memory and learning procedure.