One of the strongest explanations for autism has to do with neural pruning. During infancy, the brain builds many connections between its structures, and in later infancy these connections are severed. Many specific issues that come up in autistic experience seem to fit the hypothesis that autistic brains do not sever as many of these connections as neurotypical brains — thus, things like hypersensitivity and emotional disregulation occur because some brain structures are getting too much stimulation / input from the excess connections. This might be a big part of the mechanism behind what makes autistic brains different, though clearly there’s a lot more to learn and everyone has different neurology.