Do brain cells undergo mitosis? how about neurons? please also explain why?

No, they stop after your born. why? imagine what your mind would be like if it was constantly growing. how would you think with your mind practicaly melting and changing shape everyday. it wouldnt be able to do anything. every cell in your mind makes new connections to other cells, which make other connections. imagine if they replicated. it would just mess everything up. and that would suck. lol