My EEG friend and I have debated and studied that for a lifetime! One of the most outstanding concepts I have ever learned comes from an anaesthesiologist MD named Stuart Hameroff. He wondered what happened to ‘consciousness’ under anaesthesia and why it sometimes did not work on some people. Thus proceeded a life-long rabbit-hole of ‘quantum consciousness’ that borders into the metaphysical.
Dig into “Stuart Hameroff” if you want to learn more. You can start here:
Dr. Stuart Hameroff: Consciousness is More than Computation!
Warning!: This is a deep rabbit-hole that will challenge your world view.