Right angular lesion and selective impairment of motion vision in left visual field.

Abstract

A 45-year-old right-handed man had, for more than 20 years, a depressed fracture of the right parietal bone and selective impairment of movement vision in the left visual field; an illusory overestimation of speed of moving objects and extreme sensitivity to moving stimuli. Visuo-spatial perceptions of immobile objects, and other visual functions were normal apart from slightly decreased stereoacuity. The extent of depressed fracture corresponded approximately to the right angular gyrus. Carbamazepine or phenytoin did not alter the symptoms. After the operation, his symptoms were restricted to peripheral parts of the left visual field, with transient overestimation of speed of moving objects in the right hemifield. It was suggested that the human angular gyri may be involved in the central mechanisms of movement perception, and shift of visual attention or gaze to moving stimuli in contralateral visual field, especially in its peripheral part.