That's a huge stretch. For starters, we know that the brain is extraordinarily good at inventing detail to fill in gaps. A lot of what you think are memories are pure fiction propped up by sufficient real information to pass.
There are many much more likely scenarios to rule out long before there's any reason to consider those ideas, and in most cases there is no reliable way of ruling them out, because there's been insufficient controls in place (unsurprisingly, given that it's not why they are there) - just like a cold reader can extract vast amounts of information from people without them realising, so can normal people with a fascinating story that gets people involved. Anyone that have talked to anyone present in the operating theatre afterwards, for example, can not be considered a reliable source, because lots of information might have been filled in (and such information can easily get recalled as memories by the patient later, without any intent to deceive).
I think both you and the other commenter are assuming I was referring to something religious. I most assuredly was not, nor is Dr. Parnia.
Read the article. The quote from Dr. Parnia that sums up his thoughts:
"All I can say is what I have observed from my work. It seems that when consciousness shuts down in death, psyche, or soul – by which I don't mean ghosts, I mean your individual self – persists for a least those hours before you are resuscitated. From which we might justifiably begin to conclude that the brain is acting as an intermediary to manifest your idea of soul or self but it may not be the source or originator of it… I think that the evidence is beginning to suggest that we should keep open our minds to the possibility that memory, while obviously a scientific entity of some kind – I'm not saying it is magic or anything like that – is not neuronal."
Really, this should be obvious. If a human being emerges alive on the other end of a two-hour period with no neuronal activity, then is simple neuronal activity really what comprises a human's selfhood? I'm not saying it's magic or religion, but at the very least it's interesting to think about.
As someone who has had a neurological illness that impacts my memory, I can assure you that it is neuronal.
All of this 'resumption' of being/existence means is that the same structures that were in place before the intervention persist through the duration of the surgery. Which is exactly the point of interventions like this - to make sure that the brain can resume its normal activity.
If your brain is identical to itself after as it was to before then you will have continuity of subjective experience.
The obvious proof of this is that you go to sleep every night. That is a loss of consciousness, during which you are dormant. In some sense, you don't fully exist when you are asleep. Nonetheless when you wake up in the morning your brain constructs you as you yet again, mostly the same as you were the night before.
Your brain simply remembers how to be you. Your brain remembers how to be perceived by itself as itself. This includes your outward personality but also your inward subjective experience. That is why we have this sensation of continuity from one moment to the next.
But as someone who has had that continuity broken I can assure you that I wish there was some other thing that kept it going, not related to neurons. However, in my experience, it seems like there isn't.
The brain is a phenomena that requires neurons to exist, but simply having neurons doesn't make a brain. It's structural like you've said. The arrangement (and connection) of the neurons is what makes one brain different from another much more so than anything else.
As long as you preserve that structure, you're preserving the "person" as they identify themselves so to speak.
What makes the me that wakes up every single morning after having slept the same me that went to bed every night? From a consciousness perspective, it's the memories. That's the only thing I can really track that make me, me. Boot my brain up sans memories and I'm not really me. With memories I am. At least as far as I can tell.
But if you could pause your brain and make a perfect duplicate, with the same neuronal connections, and then "wake up" both you and your neuronal clone, would you experience yourself as two different entities?
And if you only woke up the clone, would it be you who was experiencing the clone's life? Or a different entity?
Based on the grandparent's logic (which I support), they would both be equally "you", assuming it was a perfect duplicate. From that point forward, the two people would have different experiences, and so would become different people, just as you have different life experience now than you did a week or a year ago, and so think and behave somewhat differently.
That said, I bet they would also have a pretty fascinating relationship: like a twins bond, except much more so. Given their shared brain structure and largely shared life experience (shared to a degree that no two separate people could), their thought patterns would obviously remain very similar. It would probably feel very much like they could read each other's minds.
If your liver starts filtering toxins on the other end of a two-hour period of clinical death with no metabolic activity, then are simple liver cells really what comprises a liver's function?
No, you missed the analogy. The analogy is that a human's essence or "selfhood" is merely the product of a successfully-functioning brain, in much the same way that toxin-processing is the product of a successfully-functioning liver.
No, I got the analogy, but it fails because only one of the two analogy relationships involves the concept of self, which is quantitatively different from a simple physical process (at the very least, it's an extraordinarily complex physical process that exceeds our current understanding).
But this is clearly flamewar material for a lot of you, so this is my last comment on the matter.
We don't understand what it is yet, but more and more data points to what you have in parantheses - that it's an extraordinarily complex physical process. But even its extraordinary complexity is simpler than the other explanation you are offering, which is the possibility of a supernatural entity, for which you have to assert a whole new class of phenomena that somehow interacts with physical phenomena but is also fundamentally different from it. Then you have to go and explain why something that isn't physical can interact causally with something that is.
When a top is not spinning, where is the spin stored?
When it's not raining, where are the rainbows kept?
I think a simpler explanation is that your self/psyche is created by the actions of the brain (or the whole CNS). When the brain is not working, they are not there. When it starts working again, they are back. They were really gone for a while: no need to resort to another vessel for them.
I'm a little mystified by his syllogism here. OK, there is no neuronal activity, but what we measure is electrical, yes? Neurons also store information chemically; and Parnia observes that keeping the brain oxygenated is essential to recovery because brain cells enter apoptosis in the absence of oxygen. I can't help feeling that this is like saying there's no electrical activity in a battery when it's not wired up, therefore the electricity must be coming from somewhere else outside the battery.
Mind, I don't necessarily disagree with his thesis; for reasons of my own I think there's something to his notion of brain-as-antenna. It might be that the writer misunderstood him or omitted some necessary context from the money quote due to a lack of scientific insight. I'll look up his book, which sounds quite interesting.
Who exactly is claiming neuronal activity forms the basis of self-hood? Sure, this might mean long-term memory doesn't need continuous neuronal activity to maintain, but I don't know anyone that thought so in the first place.
I suppose it depends on the idea of what consciousness (in terms of what constitutes the self, rather than state of alertness) is - if one considers it to be just an emergent effect of neuronal activity, then that would fit by definition.
There are many much more likely scenarios to rule out long before there's any reason to consider those ideas, and in most cases there is no reliable way of ruling them out, because there's been insufficient controls in place (unsurprisingly, given that it's not why they are there) - just like a cold reader can extract vast amounts of information from people without them realising, so can normal people with a fascinating story that gets people involved. Anyone that have talked to anyone present in the operating theatre afterwards, for example, can not be considered a reliable source, because lots of information might have been filled in (and such information can easily get recalled as memories by the patient later, without any intent to deceive).