How does agnosia affect the brain?
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.[1] It is usually associated with brain injury or neurological illness, particularly after damage to the occipitotemporal border, which is part of the ventral stream.[2] Agnosia only affects a single modality,[3] such as vision or hearing.[4] More recently, a top-down interruption is considered to cause the disturbance of handling perceptual information.[5]
Apperceptive agnosia
Auditory apperceptive agnosia are impairments in audition that take place despite intact audiogram. In some cases the deficit is in the ability to recognize spoken words, and in other cases, may be a deficit in recognizing environmental sounds. In all cases individuals are able to read, write, name objects, and converse intelligently. Similar to visual impairments, the deficit arise because of damage in the primary sensory cortex. In the case of auditory agnosia, lesions are present in the superior temporal gyrus bilaterally or in the posterior temporal lobe of the language-dominant (typically left) hemisphere. 