LOCOMOTOR MOVEMENTS IN OPPOSITE DIRECTIONS INDUCED BY STIMULATION OF PALLIDUM OR OF PUTAMEN

Stimulation of the putamen in the cat by a modified Hess technique produces turning to the ipsilateral side in a horizontal plane. With a similar threshold stimulation of the caudal margin of the putamen near to the pallidum and of the lamella pallidi externa many adversive locomotor effects are obtained. The ipsiversive movements are interpreted as being due to an inhibition of the tonically active substrate of contraversive turning. The result of putaminal stimulation seems to be that the ipsilateral pallidum is inhibited so that the contralateral pallidum becomes dominant; this results in turning to the contralateral side, i.e. that which is ipsilateral to the stimulated putamen. Stimulation of the pallidum (externum) and of the entopeduncular nucleus during these experiments confirms that adversive turning and contraversive circling are the respective effects of stimulating the pallidum and the entopeduncular nucleus. Whereas stimulation of the internal capsule above the pallidum induces predominantly contraversive turning, stimulation of the internal capsule above the putamen most often induces ipsiversive movements. © 1969.