I saw a TV show where people from the future were traveling back in time by somehow downloading their minds into a person in the past just before that person dies. We don't need to talk about plausibility, it's just completely ridiculous in every conceivable way, but one thing I thought when I saw this show turned out to be worth contemplation.
The way your brain learns is by brain cells shooting out dendrites which connects it to other brain cells, they do this your entire life from birth. Dendrites are little hairs that grow very rapidly out of every brain cell. The more you listen to/write about/talk about/ practice something the more your brain makes dendrites. Learning equals growth of dendrites.
What this means is that learning physically changes the structure of the brain so it's not as if your thoughts have no physicality at all, in fact it's the opposite of that. Not only your thoughts but the way you think is hard wired into your brain in real time.
So let's say we take a dead brain and reanimate it by forcing some kind of energy through it, what would likely come out? Most likely what would come out would be the guy who owned the brain when it was alive.