And I suppose a different persona uses different cells of the brain...

I know a man of about 60 who has a serious stammer, by which I mean long pauses while he tries to say the next word. The problem started after an appendectomy at the age of nine, so he may have suffered brain damage in the operation.

On this very screen I see an ad which says "How to Stop Stammering. 5-day intensive stutter-free speech..." I want to ask them how they can help anyone if they don't know the diff between stammer and stutter.