The brain generates our thoughts, ensures our way of thinking, stores our memories, and produces our behaviour and the consciousness.
Yet, everything this - the thoughts, the way of thinking, memories, behaviour and consciousness change. Definately not static through your entire life.
But if something is not static, then it can't be used as a personal identity, because after each change of this something, you are not you anymore.
I wonder what do you think about this issue.