[Ocular tracking movements: organization and disturbances in occipitoparietal lesions (author's transl)].

Disturbances of ipsilateral pursuit movements in unilateral occipitoparietal lesions have led to accept that each occipitoparietal region controls the ipsilateral slow movement. The study of 7 patients with unilateral occipitoparietal lesions demonstrated that the pursuit (ramp) movement directed towards the lesion is not completely absent; but that the tracking is of an extremely fragile nature and overloaded with saccades. Furthermore, though it is true that the disorganization mainly affects the pursuit ipsilateral to the lesion, it does also involve to some extent the contralateral movement. These findings suggest that the concommitant action of the two hemispheres is necessary for smooth pursuit movements to occur, by inhibiting any phasic phenomenon, but that each hemisphere is still capable of producing pursuit movements in both directions.