[Effect of ablation of the motor cortex or the cerebellum on postural-kinetic coordination in the cat].

1. A cat, restrained in a hammock, stands with its feet on supporting trays each furnished with strain gauges to measure the isometric upthrust. Placing reactions are elicited by contact of the left or right forelimb with a moving tray. The placing movement is preceded and accompanied by a postural adjustment characterized by an increase of the upthrust exerted by the opposite forelimb. 2. After ablation of the motor cortex on one side, the placing movement of the contralateral forelimb is abolished for the first few days after the operation and thereafter is delayed. However, the postural adjustment of the ipsilateral forelimb persists, with the same range of latencies as before the operation. 3. After unilateral motor cortical ablation, the contralateral forelimb still takes part in the postural adjustment associated with the placing movement of the other forelimb. 4. In two cats which had 2 years earlier undergone a total cerebellectomy, the placing movement was lacking or appeared with a long delay, whereas a postural adjustment of the other forelimb could be observed, although reduced. 5. The results indicate that the nervous structures responsible for the movement and for the associated postural adjustment are separate but partially linked.