This has probably been asked before ...but

Good question. I wonder if anyone has ever been hypnotised and reported memories during anaesthesia? My experience with general anaesthetic is the same - clear memory up to surgery, no sense of time having elapsed when I wake up.

I hardly ever remember dreams but would agree the memory and sensation after anaesthetic isn’t the same as in sleep.

Surely they have been studies with FMRI and other brain scanning devices with subjects under anesthesia. What do they show?

https://scholar.google.com/scholar?q=mem...cQgQMIJjAA

Anyone who's had an operation under general anaesthetic knows that, at least in my case, it's the only time in my life that we really 'lost consciousness'. From the time that the chemical is injected and starting to count backwards from 100, 99,98, 97,96....then waking up maybe hours later! 

This seems to imply that our consciousness can be switched off by drugs. 

If it can be switched off by drugs, why not switched on by drugs? i.e. Generated by the brain.

Thoughts?

From what I've read, Stan the mechanism that allows general anaesthetic to render us unconscious is a complete mystery. I personally don't think anything gets switched off per-se (as in disappears), if it did why would the same person emerge with the same mannerisms and memories.
Also patients have NDE's whilst under the influence of very heavy anaesthesia (and EEG  monitored), out of body experiences etc so the mind was very much functioning.

A better example to confound the critics is terminal lucidity. No brain left but still conscious.

 http://content.time.com/time/printout/0,...92,00.html

But it wasn't David's brain that woke him up to say goodbye that Friday. His brain had already been destroyed. Tumour metastases don't simply occupy space and press on things, leaving a whole brain. The metastases actually replace tissue. Where that grey stuff grows, the brain is just not there.

From what I've read, Stan the mechanism that allows general anaesthetic to render us unconscious is a complete mystery. I personally don't think anything gets switched off per-se (as in disappears), if it did why would the same person emerge with the same mannerisms and memories.
Also patients have NDE's whilst under the influence of very heavy anaesthesia (and EEG  monitored), out of body experiences etc so the mind was very much functioning.

A better example to confound the critics is terminal lucidity. No brain left but still conscious.

 http://content.time.com/time/printout/0,...92,00.html

But it wasn't David's brain that woke him up to say goodbye that Friday. His brain had already been destroyed. Tumour metastases don't simply occupy space and press on things, leaving a whole brain. The metastases actually replace tissue. Where that grey stuff grows, the brain is just not there.

That's a great example of terminal lucidity Tim.

Have you the same experience as me when having an operation? It is unique in my life, I have to say.

Additional thoughts from the doctor above.

What woke my patient that Friday was simply his mind, forcing its way through a broken brain, a father's final act to comfort his family. The mind is a uniquely personal domain of thought, dreams and countless other things, like the will, faith and hope. These fine things are as real as rocks and water but, like the mind, weightless and invisible, maybe even timeless. Material science shies from these things, calling them epiphenomena, programs running on a computer, tunes on a piano. This understanding can't be ignored; not too much seems to get done on earth without a physical brain. But I know this understanding is not complete, either.

I see the mind have its way all the time when physical realities challenge it. In a patient stubbornly working to rehab after surgery, in a child practicing an instrument or struggling to create, a mind or will, clearly separate, hovers under the machinery, forcing it toward a goal. It's wonderful to see, such tangible evidence of that fine thing's power over the mere clumps of particles that, however pretty, will eventually clump differently and vanish.
Neuroanatomy is largely concerned with which spots in the brain do what; which chemicals have which effects at those spots is neurophysiology. Plan on feeding those chemicals to a real person's brain, and you're doing neuropharmacology.

Although they are concerned with myriad, complex, amazing things, none of these disciplines seem to find the mind. Somehow it's "smaller" than the tracts, ganglia and nuclei of the brain's gross anatomy--but "bigger" than the cells and molecules of the brain's physiology. We really should have bumped into it on the way down. Yet we have not. Like our own image in still water however sharp, when we reach to grasp it, it just dissolves.

But many think the mind is only in there--existing somehow in the physical relationship of the brain's physical elements. The physical, say these materialists, is all there is. I fix bones with hardware. As physical as this might be, I cannot be a materialist. I cannot ignore the internal evidence of my own mind. It would be hypocritical. And worse, it would be cowardly to ignore those occasional appearances of the spirits of others of minds uncloaked, in naked virtue, like David's goodbye.

[Laird]

If [consciousness] can be switched off by drugs, why not switched on by drugs? i.e. Generated by the brain.

I don't think that the one follows from the other, Steve. In my view, consciousness is not the brain, and nor is it "generated" by the brain, but it has some sort of relationship with the brain. This is compatible with consciousness being "switched off by drugs" i.e. it is because the relationship is two-way that the physical - drugs in the brain - can affect the non-physical - the conscious mind, even to the point of apparently "turning it off" (but only whilst it remains in relationship with the physical brain).

But I would question this apparent "turning off" anyway. I have been under general anaesthetic several times, and I would not be confident in saying that I had no experiences whilst I was under - certainly, it seems that way, but who knows what I'm failing to remember? In other words: are you 100% sure that you were utterly unconscious, or is there a possibility that you had experiences under anaesthetic but simply failed to recall them? (Not that it matters, given what I wrote above).

In any case, how is this any different from arguing that having a certain number of drinks makes one drunk, and that therefore, given that alcohol is a physical drug, consciousness must be generated by a physical brain... or any of a number of other similar scenarios?

[Laird]

It baffles me why some members are so set against brain creating consciousness.

Perhaps then you should read the philosophical arguments, e.g., see Titus Rivas's Analytical argument against physicalism and What's wrong with panpsychism? threads in the Philosophy forum. Or perhaps you have not understood the empirical arguments - that it appears from multiple reports, some including veridical information, that consciousness can continue vividly, and/or travel to distant places, when the physical brain is for all intents and purposes dead and/or insensible to the information gathered at the distant place/s.

That's a great example of terminal lucidity Tim.

Have you the same experience as me when having an operation? It is unique in my life, I have to say.

Thanks, Stan. I've had two operations,  one when I was a kid and one about 10 years ago. I don't recall anything unusual about them, no memories.

 Dr Rajiv Parti's out of body experience under general anaesthesia is a good example though. He's an anaesthesiologist (as I'm sure you know). In the first chapter of his book he talks about not just his own OBE during anaesthesia but that of a patient who was undergoing hypothermic standstill to have a ruptured aorta (I think) fixed.

The patient's head was packed in ice there was nothing happening in his brain. He described the operation from a vantage point, details he couldn't possibly have known about. Parti (apparently) was unnerved by it and wanted him to shut up but the man simply carried on with more details until Parti prescribed a dose of Haldol to quiet him down.