Abstract
Visual agnostic symptom is classically divided into two types ; apperceptive and associative type. Based on pathological visual form information process, the term of integrative type had been added to those two classical types and new classification by three types was recently proposed. Lesion analyses leveled that the bilateral medial occipital cortices are responsible for apperceptive type. Integrative and associative types are related to damage in the medial temporo-occipital cortex though it is not clear yet which part in this area is responsible for each type. Results of brain imaging studies, however, showed that activation in the lateral occipital cortex during visual form processing task. Putting together these clinical and experimental findings, it may be possible to account for those three types in terms of visual processing neural route as follows ; apperceptive visual agnosia could occur if visual information process from the medial to the lateral occipital cortex is severely damaged. If this route works partially, visual agnosia could be regarded as integrative type. Damaged in the following rostral route but not in the lateral and the medial occipital area, the symptom could be associative type. Thus by suggesting the neural route for visual form information, responsible area for each of three types of visual agnosia was explained theoretically.
