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.
Amusia
Clinical symptoms of acquired amusia are much more variable than those of congenital amusia and are determined by the location and nature of the lesion. Brain injuries may afflict motor or expressive functioning, including the ability to sing, whistle, or hum a tune (oral-expressive amusia), the ability to play an instrument (instrumental amusia or musical apraxia), and the ability to write music (musical agraphia). Additionally, brain damage to the receptive dimension affects the faculty to discriminate tunes (receptive or sensorial amusia), the ability to read music (musical alessia), and the ability to identify songs that were familiar prior to the brain damage (amnesic amusia).