Answer to Question 1
The organization of the auditory cortex strongly parallels that of the visual cortex. For example, just as the visual system has a what pathway and a where pathway, the auditory system has a what pathway sensitive to patterns of sound in the anterior temporal cortex, and a where pathway sensitive to sound location in the posterior temporal cortex and the parietal cortex. Just as patients with damage in area MT become motion blind, patients with damage in parts of the superior temporal cortex become motion deaf. They hear sounds, but they do not detect that a source of a sound is moving.
Just as the visual cortex is active during visual imagery, area A1 responds to imagined sounds as well as real ones. It becomes active when people view short silent videos that suggest soundsuch as someone playing a piano, or a glass vase shattering on the ground. In one study, people listened to several familiar and unfamiliar songs. At various points, parts of each song were replaced by 3- to 5-second gaps. When people were listening to familiar songs, they reported that they heard in their heads the notes or words that belonged in the gaps. That experience was accompanied by activity in area A1 . During similar gaps in the unfamiliar songs, they did not hear anything in their heads, and area A1 showed no response.
Also like the visual system, development of the auditory system depends on experience. Just as rearing an animal in the dark impairs visual development, rearing one in constant noise impairs auditory development. (In constant noise, it is difficult to identify and learn about individual sounds.) In people who are deaf from birth, the axons leading from the auditory cortex develop less than in other people.
Answer to Question 2
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