Loss of visual imagery and defective recognition of parts of wholes in optic aphasia

Symptoms of optic aphasia and visual agnosia in the same patient may help t o elucidate relationships and boundaries between the two types of clinical expression. Likewise, patients presenting dissociations between visual imag ery and visual perception provide an opportunity to gain insight into their functional organization. This study reports the case of RG, a 68-year-old right-handed man who had a left occipital cerebrovascular accident resultin g in a severe loss of visual imagery, optic aphasia, for all categories of objects except depicted body and face parts and parts of objects, for which he presented visual agnosia, Semantics and structural descriptions seemed to be spared, It is suggested that the characteristics of the stimuli that triggered faulty visual recognition, combined with both his optic aphasia ( 'bottom-up' processes) and loss of visual imagery ('top-down' processes), c ould account for the selective visual agnosia.