Defensive behavior induced by stimulation of the ventral striatum in the cat

The behavioral responses induced by electrical stimulation of the ventral striatum were studied in 15 freely moving cats, chronically implanted with multiwire electrodes. Two types of defensive responses could be evoked from the ventral striatum, an arrest response and an escape or flight reaction. Stimulation of the dorsal striatum and the internal capsule induced contralateral head turning and movements of the face or limbs. The number of ventral striatal sites eliciting escape responses increased along the sessions, while their threshold decreased. Lesioning the ventral pallidal region with kainic acid increased significantly the threshold for defensive responses, whereas head turning responses showed no change. The results of this study indicate that the ventral striatum could be part of the neural substrate for defensive behavior, and that the ventral pallidal region plays a role in its mediation.