The brain has a high level of plasticity. So, if you view it as a lens through which you can experience this realm through, and the lens is malleable to the peculiarities of this realm, it makes sense that the brains experiences result in shaping the lens and therefore your experience of this realm.
For example: Bodybuilder Lex Reeves is a fat sack of shit, who lives with his mum, was bullied by physically superior specimens all his life and his lens has been warped into spending his time trying to seek revenge through the art of trolling bodybuilding sites. However, his conscience, when it leaves this realm, will revert to a body-less state where it will no longer be shackled by the pea-brained thinking that he currently displays.