User blog comment:The Milkman/Everybody Shut Up./@comment-1341687-20120423035921/@comment-1341687-20120423041418

I actually have an answer for that but it's my own speculation.

Shepard was dead. Brain dead. You just don't get better from that. Yet all of a sudden he does? I can see that being true. But only with the help of sufficiently advanced AI. It handles all of his higher brain functions and everything now. That's why all the questions and tests are so important as well as bringing them back how they were. Shepard is part AI at least with most likely, Reaper-tech. It would be possible with the AIs help for their brain to repair itself which is why they have a chance of living.