Optic aphasia is a visual modality-specific naming disorder. It has sometimes been grouped with associative visual agnosia, but these patients are not agnosic since they can demonstrate recognition of visually-presented stimuli by means other than naming, e.g., gesture. Moreover, these patients are not handicapped by their deficit in everyday life, whereas agnosic patients are often functionally blind. Objects that are semantically related can be appropriately sorted, indicating intact semantics. This is not simply anomia, since the deficit is specific to visual stimuli; objects presented in tactile modality, or by sound, or by spoken definition can be named. Naming errors are often semantic, and perseverations ("conduit d’approche") are common. Perception is intact, evidenced by the ability to draw accurately objects which cannot be named. Reading is poorly performed.
Optic aphasia is associated with unilateral lesions of the left occipital cortex and subjacent white matter.
The neuropsychological explanation of optic aphasia is unclear. It may be a mild type of associative visual agnosia, despite the differences.
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Lhermitte F, Beauvois MF. A visual-speech disconnection syndrome: report of a case with optic aphasia, agnosic alexia and color agnosia. Brain 1973; 96: 695-714
Cross ReferencesAnomia; Conduit d’approche; Visual agnosia