I know Richard Feynmann used sensory deprivation chambers a number of times. I don't know that he did it for any reason other than it was interesting to him what he could do. He wrote about being able to move his center of consciousness out of his head.

I suspect that the reason for this is that several of our main sensory organs are on our head. Without those, there's no reason to think that our mind is there.

I am the Doctor, and THIS... is my SPOON!