[Modification of the strategy of intentional movement after lesions of the substantia nigra in the cat].

Bilateral lesions of the substantia nigra were carried out in cats previously overtrained at performing a visually guided forepaw movement towards a moving target. Both their reaction time (RT) and movement time (MT) were impaired postoperatively. On the other hand, their pointing precision was unimpaired after lesion and even improved relative to the preoperative level. This improved accuracy persisted even when the duration of the movement had returned to normal. It is suggested that lesioned animals develop and keep a new strategy using visual feed-back throughout the movement, while normal cats, even on such a complex pointing task, mainly use visual information to trigger their movement.