Visual agnosia and optic aphasia: are they anatomically distinct?

A patient with left infero-medial occipital-temporal infarct suffered a visual agnosia that, by a minor change of the task, could be manipulated to optic aphasia. Tools in actual use and pantomimes of tool use were better named than stationary tools, a dissociation that suggests differences in the ability of stimuli to evoke associations over multiple modalities. Based on this case and analysis of previous reports we suggest that optic aphasia differs from visual agnosia primarily in the degree of callosal disconnection and that the preserved demonstration of tools use and semantic classification of optic aphasia reflect right hemisphere contribution to visual processing.