Impairment of hand movements under visual guidance.

Impairment of object-bound movements of the hand performed under visual guidance ("optic ataxia") was a prominent sign in a patient with bilateral circumscribed infarctions in the posterior watershed territory. The sign was interpreted as resulting from defective integration of panoramic visual information with proprioceptive information concerning the upper extremity, and as being related either to damage of structures in the parietooccipital junction or their neural outflow to the premotor region.