Dynamic interaction between caudate nucleus and hypothalamus.

Continuous low frequency stimulation of the caudate nucleus by constant parameters leads to the appearance of a characteristic "caudate spindle" as well as other "inhibitory" electrophysiological responses (single unit activity intracellular recordings) varying in duration and amplitude in the cerebral cortex. Computerized data processing of the responses (amplitude and duration of individual spindles, numbers of single unit blocking and sizes of EPSP and IPSP) indicated increments and decrements appearing in stable and characteristic sequences. The same low frequency caudate stimulation produces fast bursts in the course of continuous stimulation. The variations and dynamic patterns of inhibitory caudate influences upon the cortex seem to be in equilibrium with the excitatory influences from the hypothalamus representing a unique regulatory system.