Lots of imaging studies have been done on the brains of autists, including some showing increased thickness of the visual cortex. This study shows, for the first time, increased thickness of the primary auditory cortex. As one of the authors points out, "(T)he visual and auditory cortical thickness increases may be related to enhanced visual and auditory perception in autism."
This would go some way toward explaining the sensory overload autistic kids seem to experience. It might explain how Temple Grandin sees things other abbatoirists don't.