Clint offered us:
This is a highly informative piece, attempting to explain a variety of theories. *Well* worth the read.
I would have to fall into the camp that savants are able to access underlying data representations. My *eye* can perceive detail and my ear can probably hear "perfect" pitch (assuming I'm not defective genetically). So the "condensing" of information for higher level consideration may involve some information loss.
Now the math ability is interesting, since there is no evolutionary argument that complex mathematics is selected for in any way. (Simple counting maybe, square roots or complex divisions very doubtful.) So *either* the brain is so general that it can absorb and overlay math on other sub-processes *or* the argument is correct that the math savants are recruiting larger brain regions for the job.
So perhaps, depending on the skill, there are different factors at work.
But *highly* fascinating given the possibility that devices, drugs or nanobots could turn these processing skills on or off on demand!