Abstract
We reported on a 74 -year-old right-handed man who displayed visual associative agnosia due to cerebral infarction. His agnosia was accompanied by left upper quadranopia, prosopagnosia, pure alexia, color naming difficulty, topographical disorientation and recent memory deficit, without Balint's syndrome. Language and general intelligence were well preserved. His visual agnosia had a salient feature in that the presentation of an object at an unusual angle, without kinesthetic clues, caused an increase of visual recognition difficulty compared to an object shown to him in a natural position. This phenomenon has been described as visual static agnosia. MRI revealed bilateral temporo-occipital lesions which included bilateral inferior longitudinal fasciculi and defined lesions in bilateral parieto-occipital junctions.
It has been recognized that visual information processing in the human brain may be carried out by two parallel, distinct neural pathways: the dorsal, occipito-parietal projections of the visual system for the analysis of spatial information and the ventral, occipito-temporal projections for the recognition of visual patterns. Given this theory, the subject's clinical neuropsychological and neuroradiological findings suggest that the damage to bilateral occipito-temporal projections may cause visual associative agnosia, and that compensation by the function of the occipitoparietal projections following the geniculostriate visual system might participate in the genesis of his visual static agnosia.
