Hippocampal theta rhythms from CA1 and dentate generators during paradoxical sleep of the rat: differential alterations after septal lesion.

Hippocampal theta (theta) rhythm was recorded from CA1 and dentate generators respectively, before and after septal lesion in the freely moving rat. It was observed that theta recorded from CA1 generator and theta recorded from dentate generator can be differentially affected by the lesion. In agreement with our previous data, these findings strongly support the hypothesis that CA1 and dentate generators producing the hippocampal theta are functionally independent. The existence of two independent septo-hippocampal neural systems which might mediate theta CA1 and theta dentate separately is discussed.