The proposed work for the period of 9/1/74 through 8/31/75 includes the following: (1) We have previously mapped evoked gross potentials, focal potential and single-unit responses in the primate striatum (caudate and putamen) to stimulation of the cerebral cortex in decerebrate monkeys. We now plan to study in a similar fashion the input organization of the striatum with respect to inputs from the thalamus and substantia nigra (all studies in Macaca mulatta). (2) Having as complete maps as possible on the topographic organization of striatal inputs, we plan to study striatal output organization by recording focal potentials and single cell responses in the globus pallidus and substantia nigra in response to stimulation of different regions of the striatum. Hopefully we will arrive at a better understanding of the overall topographic patterns characterizing striatal input-output organization. (3) Finally, we hope to utilize electrophysiological criteria developed earlier (e.g., cortico-striatal evoked potentials) for accurate placement of a "lesioning" probe in specific regions of the striatum (e.g., the area receiving input from the orbitofrontal cortex, etc.), and determine the behavioral changes resulting from such lesions (specifically, can choreiform or athetoid dyskinesias be induced by appropriately placed lesions)?