hmmm... I met up with a bunch of old friends, from school, the other day. Over the years all the cells in their brains and bodies have changed, and they don't look as they did when we were at school. Most of the views about things have also changed due to their varied experiences and so on. However they are still recognizably the same people (selves); we can even pick up the same conversations we were having 40 odd years ago.
My mum has dementia and her memory and some other thinking processes are disintegrating daily, are we supposed to pretend we don't know who she is?
What makes up this illusory self? It's not physical cells certainly .. it's not even information as this can also change, more to do with how information is processed.