I remember Roger Penrose talking about the mystery of anesthetics, how they may target the vast "microtubule" network in the brain, itself a pretty surprising and unknown structure.
In this case, his dentist used local anaesthetic. Penrose was referring to general anaesthetics and their effect on consciousness.
He spoke last week about it at The Towards a Science of Consciousness conference (Univeristy of Arizona) Stuart Hammeroff and Penrose have the Orc OR Theory of Consciousness. Stuarts an anesthesiologist