For nearly his entire life, Dr. Stuart Hameroff has been fascinated with the bedeviling question of consciousness. But instead of studying neurology or another field commonly associated with the inner workings of the brain, it was Hameroff’s familiarity with anesthetics, a family of drugs that famously induces the opposite of consciousness, that fueled his curiosity.

“I thought about neurology, psychology, and neurosurgery, but none of those… eemed to be dealing with the problem of consciousness,” says Hameroff, a now-retired professor of anesthesiology from the University of Arizona. Hameroff recalls a particularly eye-opening moment when he first arrived at the university and met the chairman of the anesthesia department. “He says ‘hey, if you want to understand consciousness, figure out how anesthesia works because we don’t have a clue.’”

Hameroff’s work in anesthesia showed that unconsciousness occurred due to some effect on microtubules and wondered if perhaps these structures somehow played a role in forming consciousness. So instead of using the neuron, or the brain’s nerve cells, as the “base unit” of consciousness, Hameroff’s ideas delved deeper and looked at the billions of individual tubulins inside microtubules themselves. He quickly became obsessed.