Species typical display behavior following stimulation of the reptilian striatum

Seventy unanesthetized, unrestrained western fence lizards (Sceloporus occidentalis) were electrically stimulated through implanted electrodes. Behavior elicited included the species typical assertion display, elements of the challenge display and elementary locomotor responses: circling, rolling and curling. The assertion and challenge displays were elicited from telencephalic sites whereas the elementary locomotor effects were elicited from electrodes in the brain stem. Assertion displays were consistently elicited in 25 animals at an average threshold current of 46 microA. Sites showing the lowest threshold and greatest reliability were tightly clustered in the striatum and nucleus accumbens. Challenge behavior was elicited in eleven animals at an average threshold of 58 microA. Seven of the animals with challenge responses had electrodes in a small area anterior and dorsal to nucleus sphericus. The implications of these results are discussed relative to current views of the comparative neuroanatomy of the basal ganglia and relative to the basic functional organization of the vertebrate central nervous system.