SHOOT: Excellent article from the New York Times. Have a look, in particular, to page 2, and the work done on schizophrenics etc.
For example, researchers have discovered that some areas of the brain combine information from several senses. Vision, hearing and touch are initially processed in the primary sensory regions. But then they flow together, like tributaries into a river, to create the wholeness of a person’s perceptions. A dog is visually recognized far more quickly if it is simultaneously accompanied by the sound of its bark.