Apperceptive agnosia
Each patient that suffers from apperceptive agnosia does not have brain damage in exactly the same area. However, brain damage in proximity to the occipital lobe is largely correlated with the patterns of deficit seen in apperceptive agnosics. For example, patient JB suffered extensive damage to the parietal-occipital areas to the left cerebral hemisphere leading to his deficit in the ability to name distinguish between structurally similar object.
Apperceptive agnosia
Tactile apperceptive agnosia results in the inability to shape representations specific to tactile modality. The impairment is restricted to the hands even though sensation is not impaired. This is similar to visual apperceptive agnosia in that it is a basic level of processing that is impaired. Some individuals are unable to recognize objects by touch because of a small cerebral infarction.