A majority of stroke victims loses the ability to track objects in their visual field on the side opposite to the part of the brain damaged by the stroke. This condition is known as VISUAL NEGLECT and the cause of this visual impairment is damage to those areas of the brain responsible for the integration of vision, attention and action, not the actual area of the brain responsible for sight itself.
UK researchers led by Dr. David Soto from Imperial College London in a study on 3 patients with visual neglect found that all 3 could identify colored shapes and red lights in the impaired side of vision when they are listening to music they liked. The researchers believe that listening to pleasant music give rise to positive emotions which help efficiency in signaling in the brain. Here is another case of music being the best medicine