The spontaneous theta rhythm recorded from the hypothalamus posterior in the cat in vivo.

Rhythmical slow activity (theta) was mapped in the hypothalamic region in freely moving cats. We recorded well synchronized and high amplitude theta rhythm in the medial part of the hypothalamus posterior area. The EEG recordings made from lateral part of this hypothalamic region contained only irregular activity. These findings support earlier observations concerning the topography of hippocampal formation desynchrony and synchrony system. The observations of the present study also suggest that the hypothalamus posterior area is actively involved in the mechanisms responsible for generating theta oscillations in the cat.