The “caudate-spindle” III. Inhibition by high frequency stimulation of subcortical structures

1. 1. In cats, high frequency stimulation of a number of subcortical structures reversibly abolishes spindle bursts triggered by low frequency stimulation of the caudate nucleus. 2. 2. Cortical spindles induced by either the ipsi- or contralateral caudate could be inhibited by high frequency stimulation of the mesencephalic reticular formation, the hypothalamus, the globus pallidus (incl. the n. entopeduncularis), the fields of Forel and some medial thalamic nuclei ( e.g., the nucleus centrum medianum). 3. 3. More rostral and lateral structures ( e.g., the caudate itself, the putamen and the ventral anterior nucleus of the thalamus) produce a unilateral effect at threshold intensities of stimulation. Spindles caused by stimulation of the ipsilateral, but not of the contralateral caudate were inhibited under these conditions. 4. 4. High frequency stimulation of the medial amygdala, rostral thalamic midline nuclei and the relay nuclei failed to block “caudate-spindles”. 5. 5. Spindle-producing sites were also studied and found to coincide largely with recruiting sites.