The brain is the most complicated structure in the known universe. The probes currently available to science- fMRI and GSR - are both gross measures of cortical electrical activity. They're enough to start to explore apparent structural and (gross) electrical correlation between brain areas and (gross) alterations in "consciousness", in this case unconsciousness invoked via propofol and ketamine. Fair enough.

However, it irritates me when I hear scientists loosely throw the word "consciousness" into these studies and here's why.

In these studies, consciousness is always implicitly defined operationally as the electrical activity in some identified networks- DAT and DSM and front-parietal and sensory motor etc.. But the concept of consciousness has another life in philosophy where in works by people like Patricia Churchland and others, it references something more subtle- the mystery of why there should be anything we call experience at all.

Experience itself doesn't seem to be necessary to the working of any machine, including our brains. We don't think our TVs have any experiences despite (being capable of) accurately representing all human visual experiences. The reason we don't think they experience what they're displaying is because we know how they work and we know there's no ghost in the machine. Adding on "experiences" to an explanation of how TVs work is gratuitous and unnecessary.

But that's not the case with humans-just the opposite. Experience is absolutely foundational.

Descartes tried to boil his world down to what he could know with absolute certainty and arrived at his famous "Cogito ergo sum" formulation, but actually, he skipped a step; that step is simply- "There is experience".

Experience is perfectly gratuitous to any explanation of brain activity since all that activity, like an electrical storm, could take place in exactly the same way without it. We (our brains) could be, and most scientists believe are, very complicated, but purely mechanical machines. They could be exactly as they are with no more awareness- not to say feedback loops- than a blender.

But that account leaves the problem of experience or consciousness completely untouched. That would be O.K. except we know we have it.

The mystery of consciousness is not totally defined by questions like of "can I make you unconscious or conscious?" or "can I cause you to have this or that illusory experience by stimulating your brain?". The mystery of consciousness is why is there anything like experience at all ?

So whenever I read a paper that makes some confident assertion about consciousness, it gets under my skin. It's electrical activity and perhaps human behavior and speech they are actually examining, not consciousness. I hear these papers gratingly assuming the consequent with respect to the biggest mystery there is. They are implicitly saying "this is consciousness, this pattern of electrical activity in the brain and here is what we have discovered about consciousness". That's one perspective, but to philosophers, both academic and non-academic, it's a form of punting on the real question.

Consciousness is to brain science what AGI is to AI. Researchers just love to make assertions and grand predictions.

Actually the correlation between the two is closer than that since strong AI claims that consciousness can be captured in a computer; Kurtzweil and his Singularity concept is in this school of thought.

He and people like him claim that not only does experience arise as a direct result of brain activity but any substrate- including general purpose computer platforms- will similarly give rise to the same experiences if only they are programmed in a particular way, specifically, if the computations are functionally equivalent to the brain's computations.

Are badly programmed computers therefore experiencing chaos? Well, why not? Are simpler computers, like a thermostat which "experiences" temperature changes, also somehow dimly conscious? If that seems like a straw man argument to you, you should know Marvin Minsky bought it and so do a lot of other scientists whether they realize it or not.

All of this is just a non-starer to people like me. You don't get to skip a step because it keeps your theory neat or provides you the promise of immortality because you uploaded your "you" to a machine.

Consciousness, understood in this way, is a genuine mystery which for now at least I don't think we have the conceptual tools to even define much less make pronouncements about.