Lack of similarity between the effect of lesions of the suprachiasmatic nucleus and subparaventricular hypothalamic zone on behavioral circadian rhythms.

Rats were submitted to electrolytic lesion of either the suprachiasmatic nucleus (SCN) or the subparaventricular hypothalamic zone (SPVH) and the effects on circadian behavioral rhythms were compared. While the SCN lesion abolished the circadian rhythmicity of all behavioral patterns, the SPVH lesion only abolished that of the eating and drinking behavior and reduced the amplitude of a behavioral item usually associated with REM sleep.