Optic aphasia and the right hemisphere: a replication and extension.

Optic aphasia is a rare, visual modality-specific naming disorder. We describe a patient who developed this disorder subsequent to a left occipital lobe infarction. Like another case that we described previously, this patient performed normally on a variety of tasks assessing the recognition of objects he could not name. Additionally, although he never read aloud a single word, his performance on lexical decision and word comprehension tasks was far better than chance. We suggest that his performance was mediated by a right hemisphere semantic system.