like the brain is literally encased in the body so how can it be separate? like if you go around licking lamp posts you’re going to pick up some germ that’s gonna make you feel like crap and you get insomnia or fever and your brain will definitely be impacted. and so you’ll have short temper and that’ll get you into trouble.
Are you talking about consciousness? As this is separate from the mind. It would disappear from being encased within the body without a mind just as it would without a heart being that the body without these elements is not capable of reaching consciousness because it’s not capable of sustained living.
Note: it has not been scientifically proven yet that the consciousness resides in an exact spot in the brain hence they speak of consciousness and mind as separate.
Note also that there have been people who lived their entire life missing about 80% of their brain (or more https://www.sciencealert.com/a-man-who-lives-without-90-of-his-brain-is-challenging-our-understanding-of-consciousness ) without even realizing it
One case where the brain was only a crust within the scull bone and still had an operating consciousness.