Agnosia
Agnosia is the inability to process sensory information. Often there is a loss of ability to recognize objects, persons, sounds, shapes, or smells while the specific sense is not defective nor is there any significant memory loss. It is usually associated with brain injury or neurological illness, particularly after damage to the occipitotemporal border, which is part of the ventral stream. Agnosia only affects a single modality, such as vision or hearing. More recently, a top-down interruption is considered to cause the disturbance of handling perceptual information.
Neural processing for individual categories of objects
Studies of patients with brain damage have revealed pure agnosic disorders that selectively impair recognition of specific object categories. Such agnosic disorders have been reported for faces (prosopagnosia), living vs. nonliving stimuli, fruits, vegetables, tools, and musical instruments among others, suggesting that such categories may be processed independently within the brain.