What's Happening in the Brain When You're Under General Anesthesia?

Anisthesiologist is a member of three national academies. He's particularly interested these days in the basic science of anaesthesia. How does anaesthesia work? What's happening in brain when someone is under general anaesthesia? And what does that tell us about not just how we can make anaesthesia better, but also like to use anaesthesia as a window into the basic functioning of the human brain.