the brain is way, way , WAY too complex, in fact it contains 'your soul; your memorys, not just your personality, but the memorys of how your brains works the body !, in fact for all your knowledge, memory, languages, dreams, thoughts, and fears and even the 'soul' (if you believe in that sort of thing) only takes up 10% of the brain's 'processing' the rest is well, it works the body, it regulates the muscles, nervous system, heart beats, senses, the bowl movements, the food disgestion, excrements, immmune system, skin growth, hair growth, eye's adjustment for visual information intake, even the way the body works for 'langugae processing' like deaf people's brain might work different from heaing people's , obvious example of this is the linguistic aspect of body language-reading and so on
this is the stupidest question id ever come across, ok heart tranplants is possible but its only because its MOSTLY mechanical, but also highly risky, brain is well an entirely different matter all together.
leave it to sci-fi or horror movies lol
and dreams of immortality is just that, a dream.