He’s a brilliant orator with a sharp legal mind. But his expression unsettles me. I know my reaction is visceral and automatic, but as a neurologist it is my business to notice things out of the ordinary and probe them. The Senator’s atypical expressions leave me uneasy. Skill in reading faces is so fundamental to our species that 54 facial muscles orchestrate its endless nuances, which others read like a book just as we read them. Only some of these many facial muscles are under voluntary control, which is one reason it is so hard to maintain a poker face...