Unilateral visual neglect and wave P 300. A study of nine cases with unilateral lesions of the parietal lobes.

Wave P 300 was studied in nine patients with parietal lobe lesions who had visual neglect but no hemianopia. Stimulation of the hemispace contralateral to the lesion showed a lengthening in latency and a decrease in amplitude of P 300, specifically related to visual stimulation. Comparison with results obtained in 14 normal subjects and four patients with localized hemispheric lesions without visual neglect showed that changes in P 300 were specifically related to visual neglect. The parietal lobe lesions may disturb cerebral processes involved in discrimination and visual stimulus evaluation required to perform a task, inducing disturbance of the system responsible for P 300.