Prosopagnosia: a clinical and anatomical study of four patients.

We tested in great detail face perception and face memory in four cases of prosopagnosia. Three of them showed deficits of face perception and/or of familiar faces memory. There was one prosopagnosic patient, however, who showed no abnormality in face perception and discrimination and could recall familiar faces. This case suggests that a form of prosopagnosia may exist, which is due to the disconnection between face perception and face memory. X-ray CT, MRI and PET studies revealed that two patients did not have damage of the left hemisphere, supporting the view that prosopagnosia can arise from unilateral right-sided lesion.