CORTICAL SYNCHRONIZED AND DESYNCHRONIZED RESPONSES EVOKED BY STIMULATION OF PUTAMEN AND PALLIDUM IN CATS

EEG effects following stimulation of putamen and pallidum have been studied in acute cat preparations. In the drowsy state, low frequency putaminal and pallidal stimulation yields a generalized bilateral synchronization, recruiting responses, initiation of bursts, spindling and localized driving. The recruiting responses appear frontally over the ipsilateral anterior sigmoid gyrus, and to a lesser degree over the contralateral anterior sigmoid gyrus. It is concluded that these subcortical structures contribute to the nonspecific activating system. Selective electrocoagulation of the ipsilateral ventral anterior thalamic nucleus or inferior thalamic peduncle inhibits the synchronized activity. High frequency stimulation of putamen and pallidum and the adjacent internal capsule can be followed by an ipsilateral desynchronization. Low frequency stimulation of the internal capsule adjacent to the putamen and pallidum evokes a unilateral augmenting-like response over the anterior sigmoid gyrus. © 1968.