Character and origin of rotatory movements evoked by electrical stimulation of the caudate nucleus in cats

High-frequency stimulation of the caudate nucleus in cats induces three types of rotatory responses: turning the head or stepping movements in a circle toward the side opposite to that of stimulation, psychomotor excitation with contralateral rotation, and ipsilateral turning of the head and trunk. Movements of the last type developed mainly from the ventro-lateral zones of the head of the caudate nucleus, whereas psychomotor excitation, on the other hand, developed from the dorsal zones. Rotatory movements do not depend significantly on a contribution of the internal capsule or cortex. Slow synchronized activity on the EEG at the time of rotation was abolished after curarization of the animals. Caudate rotation is partly due to activation of the globus pallidus, for electrical stimulation of that structure raises the threshold of the responses although it does not block them completely.