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.
Auditory verbal agnosia
In childhood, auditory verbal agnosia can also be caused by Landau-Kleffner syndrome, also called acquired epileptic aphasia. It is often the first symptom of this disease. A review of 45 cases suggested a relationship between prognosis and age of onset with poorer prognosis for those with earlier onset. In extremely rare cases, auditory verbal agnosia has been known to present as a symptom of neurodegenerative disease, such as Alzheimer's disease. In such cases auditory verbal agnosia is a symptom that is typically followed by more severe neurological symptoms typical of Alzheimer's disease.