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Consciousness and Anaesthesia (2009) (nih.gov)
164 points by Quinzel on June 14, 2023 | hide | past | favorite | 176 comments



I practice anesthesia. My most significant change so far has been to drastically reduce the amount of ketamine I give. It is a very interesting drug. Very stable re. cardiovascular concerns. Maintains blood pressure nicely. We use it to induce anesthesia and for pain, but others use it for depression, chronic pain, borderline personality disorder.

It's fine for pediatrics. Adults not so much. We dose ketamine quite a bit higher as an induction agent at the start of operations than what would be considered a recreational or psychotherapeutic dose/"K hole".

In opposition to kids, adult patients have frequently found themselves in a very bad place on emergence from anesthesia and in the recovery room. They sometimes endorse reliving trauma and confronting themselves in a dark region of their minds that they possibly have never known about. This is why it has promise as a therapeutic agent in psychotherapy, however it is often the case that patients are cared for by one recovery room nurse who is run off her feet/has more than one patient. I have learned that "K hole" context is everything.

Kids are just fine with ketamine. I think it's because their brains are much more plastic & the variation of experience in their waking lives is higher than adults. I think that experiencing the moods and expressiveness and novel situations as a 3 year old for a day would be an incredible hallucinogen or psychedelic.


I'm also an anesthesiologist. Would be interesting to hear what you are working on.


There are four of us! (bookofjoe is an anesthesiologist as well)

I've only seen one really bad reaction to ketamine, but it was rather haunting. Still, it's a magnificent drug.


I am but a lowly senior anesthesia resident in Canada.

I can't even bill people or governments / buy a lambo yet.

Don't make fun of me for saying 'I practice anesthesia' because I do truly only 'practice' it.

I studied pain and autonomic dysfunction in grad school. My supervisor: "To test your your own patience and attention span ask somebody about their research"

I don't do anything specifically re. bench science or rats / electrophysiology now like I did then.

I was bitten by the decentralized network infrastructure / digital identity / blockchain applications bug.

Here's my first protocol that I'm legitimately proud of (quietly posting it today in a few places) --

https://violet.adasound.io/

TL;DR- I am working on nothing that people who work in hospitals are generally interested in or seeking to hear a grown man rattle on about for very long :), and what I've made public is still somewhat cryptic and lacks an advertising push..


I wonder if this will continue to be the case as generational effects work their way through, or if it is purely developmental and a universal part of becoming an adult.


I have nothing to base this on, but I suspect kids do better because they lack experience, so there is nothing to resurface. Their lack of memories prevents any sort of introspective reevaluation of their life.


I think this is a little uncharitable to kids. Do you not remember the stressors and ruminating thoughts of childhood? To say nothing of children who have experienced trauma. Perhaps this could apply to pre-object-permanence infants, but by the time they're undergoing surgery (hopefully...) they've had years of conscious experience.

Hopefully I'm not being too uncharitable, your idea is certainly plausible. I'm also just musing which feels disrespectful to the terribly interesting expert take in the ancestor comment, but I cringe whenever I hear arguments that I can reduce down to "being a child is not at all like what it is to be me", as it's been used for centuries to suppress their behavior and excuse abuses


Maybe it’s more like a volume thing.

Ketamine causes a reboot and the core memory table has to reindex.


I had anesthesia once. Subjectively it’s about as close to being dead (or simply “not existing”) as I can imagine. One moment I was perfectly awake, and the next moment I was hearing the sounds of people talking around me and I groggily became aware of my doctor getting me to acknowledge him.

There is still the question though, was my subjective experience post-surgery accurate? It’s conceivable that consciousness is suppressed to varying degrees, while the creation of memories is more significantly impacted. I may have had some degree of consciousness but my subjective post-surgery experience has no knowledge of it.

And putting aside anesthesia altogether you have the phenomena of people that get blackout drunk. For some period of time they were up, senses receiving input and processing it even if their actions were high impaired, yet afterwards there is no memory. (There are of course degrees to this too, sometimes a person remembers the tiniest pieces, as if from a dream, sometimes not at all)

The entire topic invites the question: Is consciousness required for intelligent behavior? Unless you include consciousness as part of the definition of intelligent, it is not an easy question.

Somewhat on that topic I’d highly recommend the book Being no One by Thomas Metzinger


(Queue bar talk)

Begs the question, what is intelligent behavior? Most of the time I see pretty anthropocentric interpretations of this (which are often well-reasoned) but there has to be some degree of definition that we can agree to as a starting point.

My current view is one of consciousness operating on a spectrum, some animals/creatures/entities are "more aware"[1] than others but then you have to ask whether that just leads to consciousness being a useful phenomenon for interaction with other creatures or if it's something more meaningful. Were humans conscious before the invention of language?

Another aspect of this is if "Chat-GPT" isn't conscious it kind of proves your dog is right? You're saying language/interaction isn't that big of a deal, and so it's based on biology. Not a lot different between a cat and a person if you really take a step back, let alone a chimpanzee and a person. Or maybe we're all not conscious at all in the sense that we mean it. I.e. it's just a useful illusion/delusion and evolutionary adaptation for cooperative behavior.

Then we have to insert free will, determinism, etc.

The whole thing is a mess. Most likely we're not conscious at all, nor do we have free will, as typically described. But we're conscious in that we're perceiving and our body as a whole has some amount of degrees of freedom to operate, but we're not special. Maybe that's scary idk.

[1] Whatever that means


>Most likely we're not conscious at all, nor do we have free will, as typically described.

No these aren’t likely. Consciousness is the human experience, there’s no way we aren’t conscious as that wouldn’t make sense linguistically. As for free will, anyone saying we don’t have it is doing bad science since every person knows they do. Trying to disprove humans having free will is mental masturbation and nothing more.


>As for free will, anyone saying we don’t have it is doing bad science since every person knows they do

This is a statement spoken with an authoritativeness that it doesn't deserve. There has never been a time I can remember that "free will" ever seemed real to me much less something I inherently "know"; it is at best an imprecise phrase for something I don't have a word for. The physical body is going to do what it does, the thing experiencing qualia is just along for the ride.

As for "bad science", free will as it is described seems that it would violate causality. That a macroscale effect can occur spontaneously without a paired action.


Exactly. To those who think free will is real, what exactly are you claiming is true about a particular set of atoms (shaped like a human)? Are they atoms not doing what they should do? How can a box of atoms control themselves? What does that even mean? Is physics being defied when the atoms are arranged into the shape of a brain?

Free will is literally a non sensible concept and is plainly just a subjective illusion.


1. Humans evaluate, determine, and select which causal effects to attempt/apply, among the selections in their known agency. 2. The world, given its complexity and chaos, is non-deterministic.

Humans determine their actions (will) where fate (determinism) isn't prescriptive of their course. Humans don't have a monopoly on will, but we do have our own. If you've ever survived, it's because you chose to eat. Eventually, even decisions like these which you may feel are implicit are also subject to be reversed if we want to and will.


> 1. Humans evaluate, determine, and select which causal effects to attempt/apply, among the selections in their known agency.

Explain this process in the framework of physics and thermodynamics. Specifically, what differentiates this free will process from mere causal process?


> As for free will, anyone saying we don’t have it is doing bad science since every person knows they do.

Free will: the power of acting without the constraint of necessity or fate; the ability to act at one's own discretion.

A known side effect of Parkinson’s drugs is the development of compulsive, (hypo)manic behaviors like gambling and hypersexuality — people who have been very straight laced their entire lives can change drastically. Are you suggesting that we should hold such patients equally accountable for making poor choices, as they are just as free willed as anyone else?

What of people with crippling, general anxiety, of no fault of their own, but simply as a result of genetics or exposure? If they aren’t as productive or let things slip, is that because they simply aren’t trying hard enough? (Even there — if we say one is trying harder, does that not imply an impediment to “act at one's own discretion”?)

Perhaps we should consider banning ADHD medication altogether — given everyone has free will, what practical difference does it make to put a substance into people’s bodies — they can just choose to make good decisions, right?

Of the decisions you regret, and knew that you would before acting, why did you make them? Why haven’t you just made the meta-choice of choosing to choose the right things from here on out? You can see the utility in making such a choice, right? So can you make that choice? Your discretion would likely be to make that choice, so all that’s left is to act on that discretion, which should be no problem because you have free will and you are not constrained by the natural chemical processes occurring in your brain and the physical laws that define them.


> As for free will, anyone saying we don’t have it is doing bad science since every person knows they do

And entire pillars of philosophy, having stood for millennia, crumbled under that one masterful crushing blow.


> As for free will, anyone saying we don’t have it is doing bad science since every person knows they do.

A lot of suffering exists in our society due to that belief you have regardless if it's correct or wrong and similar suffering exists in our society from beliefs formed based on knee-jerk feelings or personal biases. I agree that people have free will if we replace the term "free will" with "personal desire." However, that doesn't imply the personal desire could've been different because otherwise the person would be different as well. I've also encountered many people that remarkably don't believe in free will, so the premise you made is false.


Related to the free will discussion:

https://pubmed.ncbi.nlm.nih.gov/18408715/ (full paper can be found on SciHub)

> There has been a long controversy as to whether subjectively 'free' decisions are determined by brain activity ahead of time. We found that the outcome of a decision can be encoded in brain activity of prefrontal and parietal cortex up to 10 s before it enters awareness. This delay presumably reflects the operation of a network of high-level control areas that begin to prepare an upcoming decision long before it enters awareness.

This is unfortunately only a brief for Nature Neuroscience -- from 2008, so take with a grain of salt -- and I haven't been able to find the full paper. I also would hesitate to claim this as "lack of free will" or similar; the conclusion sentence from the brief seems to be most-accurate:

> Thus, a network of high-level control areas can begin to shape an upcoming decision long before it enters awareness.


This study was disproven. It turned out there was a software/firmware bug in the machines used for the tests (mri?). instead of thinking yeah this doesn't make sense maybe we should take a step back, they just went on with spreading misinformation of the worst kind.


If "having free will" is defined as "feeling like you undeniably have free will" and "having consciousness" is defined as "feeling like you undeniably have consciousness," then sure, it doesn't make sense linguistically to dispute that.


I think part of what makes you conscious might be your relationship with the passage of time. If you experience it you’re probably conscious. If you can relate to things that have happened or to things that will happen then you’re more conscious. This definition requires you to be able to communicate somehow, which even animals are able to do in some limited way.


You’re on the right track re: the book I recommended, it’s dense but you might enjoy. Heck the intro alone is interesting and you can probably get that through a Kindle “free preview”.

As for my response to you, I think it’s simply “yes”. And also that we lack any sort of clear & universally greed upon definitions for many of the critical terms here.

These were my areas of study, refining through ever more practical levels to cognitive science and then computational linguistics, so I know just enough to know I’m not an expert and true expertise doesn’t really exist yet for truly understanding any of this. (And my comp ling formal education has been made woefully obsolete since the time I began that path). For now, all we can do is chip away at the questions, as this linked article tries to do. Chip by chip.


To say consciousness doesn't exist is akin to taking a pen and writing "this is not ink".


Why can’t it just be a useful social abstraction? I’m not arguing scientifically that it doesn’t exist, just curious and have my own current thoughts about it.

Your eyes only focus on a small part of what you are looking at and your brain fills in the rest of the details. I think you can construct an analogy here with your pen and your eyes too.


> Why can’t it just be a useful social abstraction?

Consciousness? It sounds like you're confusing consciousness with identity, there is no social component required for consciousness.

> just curious and have my own current thoughts about it.

And where exactly are those thoughts occurring?


> there is no social component required for consciousness

I didn’t suggest that it was required. I think?

> And where exactly are those thoughts occurring?

Idk but they sure never give me a choice in which ones I get! They’re also in English. I wonder what humans “thought” before the invention of language? Grunts? Hollers? Is it any different than w old thinking “bark”?


You suggested that consciousness is no more than a useful social abstraction.

You can examine consciousness without the need for words. This is the issue with this topic, people stay in the structure of language to try to define that which language is born out of, not realizing that you can take a step back and inhabit that very thing itself and observe it directly. It just takes practice.


> You suggested that consciousness is no more than a useful social abstraction

And why not? I'm still unclear why this couldn't be the case. Maybe what we describe as consciousness developed as an evolutionary adaptation for group coordination and survival? To your earlier point about identity, it seems like you're suggesting identity and consciousness are the same, no?

> You can examine consciousness without the need for words.

I'm not sure what you mean by this. Can you elaborate?


Consciousness is the aggregate of emotional, sensory, and thought formations. With these forming a thread into a narrative through memory, we forge identities. All of this happens in the substrate that is consciousness.

If it is unclear why consciousness is not a social construct, you can experiment with isolation and introspection. Retreats, meditation, psychedelics, anything that involves observing the movements of your mind without getting tangled up into words and semantics.


> Consciousness is the aggregate of emotional, sensory, and thought formations...

That's one theory among many. Are these identities static or dynamic in nature?

> If it is unclear why consciousness is not a social construct, you can experiment with isolation and introspection. Retreats, meditation, psychedelics, anything that involves observing the movements of your mind without getting tangled up into words and semantics.

I don't find this compelling because it's really difficult to find a person who wasn't born to another person and lived amongst other people in order to run this experiment.

"Observing" myself thinking of a movie while I meditate seems circular and I don't think you can be an observer and be the observed at the same time.


It's as much a theory as saying that a body is formed of limbs, torso, head, etc. I have a body, I inhabit it and can observe it directly.

You're trying to word your way out of words.

It's like you're asking me what's atop a mountain and you keep making conjectures and assumptions about what is or isn't up there. The answer is to just go climb it instead of taking your assumptions for reality.

> I don't think you can be an observer and be the observed at the same time.

I can, because I practice it.


This is typical internet behavior but I just have to link some Chomsky talks on the topic. One's 7 minutes, and the other's 85 - I recommend the second, of course ;)

7 minutes: The Concept of a Person https://www.youtube.com/watch?v=Y0XdIT_Cn4E

85 minutes: Grammar, Mind and Body - A Personal View https://www.youtube.com/watch?v=wMQS3klG3N0

Especially relevant if you read that article yesterday "disproving" Chomsky by noting that ChatGPT exists, and wanted to consider what his rebuttal might be.

TL;DR:

  My current view is one of consciousness operating on a spectrum,
He would definitely agree

  there has to be some degree of definition that we can agree to as a starting point
He would definitely disagree, as I understand your sentiment; settling on a definition for the concept you're interested in is as impossible as settling on a definition for "meaning", "love", or "justice".

   it's just a useful illusion/delusion and evolutionary adaptation for cooperative behavior.
Alternative hypothesis discussed in the 85min talk: what if cooperation is a useful corollary for consciousness/higher level reasoning via internal linguistic structures?

  The whole thing is a mess. Most likely... we're not special
He would whole-heartedly agree, in the cosmic sense, and whole-heartedly disagree in the sense of our relation to animals.


Thanks, I want to reply but it would do the conversation a disservice without watching this video and getting on the same page. If I get some time to do so I'll try and reply.

One thing I will just throw a bone on is this one:

> what if cooperation is a useful corollary for consciousness/higher level reasoning via internal linguistic structures?

Yes! Interesting! But what is cooperation? Is it mating? Are cats cooperating by mating and then parting ways? Are wolves (yes they are I think) cooperating? Different vocalizations from different animals mean different things and animals understand that. Is there a categorical difference between those patterns and the larger (although I don't know if this applies to the range of sounds) complexity of human language?

Bonus question, how does this factor in to someone who is more well-read than someone else, or maybe knows more languages? If Chomsky or others were to suggest there's no difference and you just hit a threshold by being a human with language, it still seems a little anthropocentric to me. I'm guessing that (and it's probably a taboo subject) there is differences in consciousness between humans as well - i.e. some people are more conscious than other people. It's not binary.


I don't think one can look at this as an either or thing but a spectrum of levels too.

Almost nothing in life is 100% black and white, quite literally everything you study has more and more edge cases the more you study, even math breaks itself if you try and prove it. But we have reliable levels of math that function as we need it. And generally most things are good enough you can use it reliably. Just because something may break doesn't mean it's useless or anything.

Free will is also a spectrum and we all have different levels and different experiences of it. We all have choices we make but we might not be even aware of them. Our body influences our choices and our thinking influences our body. A double edged sword.

I remember reading an inspirational tale based on a real author who had to save himself because of his medical bills. He was completely disabled and would write blog posts with his eyes and eventually became such a good writer he was able to publish books and move to Mexico and get nurses to help care for him etc. This guy who has literally only a brain and functional eyes became some millionaire though sheer determination to save himself. Then you might find some rich well off person kill themselves because they can't find a reason to live. Two extremes. One with everything another with basically nothing, I mean would really want to live with that your whole life? Is the natural thought to reverse that?

Then you have cats able to communicate quite well with in various ways. I could go on and on about my cat informing me when he is sick etc.

I never even got into the whole thing about how your trillion of cells right now are making their own decisions in your body. I mean what even are you but a million things you'll never see or think about unless you get cancer or something when your cells decide not to die. What are you without their death?

Also could go into how memories are stored outside the brain with worm studies etc, and how fungus solves mazes, how plants communicate by smell and sound, there is a lot of werid stuff the more you look.

Bonus fun reference material:

https://unstoppable.me/life-lessons/

https://en.m.wikipedia.org/wiki/Oxana_Malaya

Teaching sign language to your cat https://vcahospitals.com/know-your-pet/teaching-and-training... https://phys.org/news/2013-07-flat-worms-retain-memories-dec...

Plants have a clicking language etc https://www.google.com/amp/s/amp.cnn.com/cnn/2023/03/30/worl...

Plants have all 5+ senses and can be trained which also is cool if you look into getting them over their fear of falling and other things etc

https://theworld.org/stories/2014-01-09/new-research-plant-i...


I also had anesthesia exactly once so far & my experiences are similar. basically remember going under and then groggily becoming aware of the doctor & being informed that operation is done. I do recall my surprise at that statement as there was no experience of passing time. I feel this was fundamentally different from sleep in quality (or even deep meditation).

I to have pondered the consciousness vs intelligence question and tentatively concluded that consciousness is useful in developing of intelligence so as to provide factors to optimize for like energy, attention, physical goals etc but beyond that its not necessary. Intelligence is basically subdividing a signal into realistic subcomponent and then putting it all somewhat coherently to come up with a bigger picture as I see it. I feel the set of tools available to current crop of AI/ML architectures are sufficient to produce a human like intelligence if we/it figures out how to assemble it the 'right' way.

consciousness OTOH, I am not sure. that (human consciousness) may be very specific to makeup of human brain and some non-modeled things in individual neurons. this does not means AGI cannot be conscious but its consciousness would be really different from human one. For humans I do lean towards Penrose's Orch-OR thesis that consciousness maybe innately quantum in nature. not sure how much evidence exists for or against it.


You guys need to read more science fiction. Blindsight by Peter Watts comes to mind.


Was going to recommend the same, it's a fairly quick read also. Watts has a version hosted on his site as well in various formats. I enjoyed the Notes and References section a lot also.

https://www.rifters.com/real/Blindsight.htm


That is one of my most favorite books of all time!


There have been people claiming that they were fully conscious while under anesthesia and felt everything, but were unable to do anything about it. I never really believed this.

One of the most terrifying things I’ve heard (from a final year med student, who was present in many surgeries) is that many patients under anesthesia react to pain. They move away from the knife, sometimes they make sounds as they’re being cut, etc. They just don’t remembers any of it afterwards.

I’ve had a few surgeries in the past and didn’t think anything of it, but now I kinda dread surgeries.


The problem is that people think of anesthesia as a single thing when it really has many different components that are managed separately. Unconsciousness is part of it, but so are analgesia (pain relief), paralysis (inability to move), immobility (loss of reflexes), and to a lesser extent, amnesia.

Anesthesia routinely involves the use of paralytics, which are separate from drugs used for analgesia (opioids or local/regional blocks) and inducing unconsciousness (propofol, anesthetic gasses). This can lead to situations where someone is paralyzed, their pain is under control (as observed by blood pressure), but the gas or propofol is insufficient to actually induce unconsciousness. Some of this comes down to individual physiology. Some of it is probably mistakes in anesthesia management.

Amnesia comes into this with the use of benzodiazepines. They can reduce anxiety before surgery. Or even during surgery if the patient needs to be awake. As a bonus, they can prevent memories from forming. Propofol can also cause amnesia, but it is primarily used to suppress consciousness.


It can happen as some surgeries require a muscle relaxant and subjective experience is hard to monitor. Ever see awake brain surgery videos?


from what I understand some forms of anesthesia just make you forget it ever happened. There are some procedures, colonoscopy is one i think, where the doctor needs you awake and able to follow commands or give feedback. The anesthesia just makes you forget it ever happened. It's really strange and kind of scary if true.


Propofol is specifically used to suppress memory of lighter surgery and procedures. Patients are conscious enough to answer questions and respond to requests, but they won't remember any of what happened.

I don't know enough about it to guess whether it actually eliminates psychological trauma or simply suppresses it so it's not conscious.

Alzheimers had a similar effect. There's a shortening window of memory which starts off normal and then gradually contracts. In mid-stage victims can't remember the start of a sentence by the time you get to the end of it.

Eventually all that's left are autonomic functions and perhaps a few very deeply engrained emotional memories.


Do you mean people answer the questions under propofol but afterwards have no recollection of the experience? If so that's exactly the type of thing I was thinking of


Anesthesia, black out drunk, and what about: before birth (and I mean eternally before, not just 9 months)? Perhaps our consciousness existed in some spiritual way, but no memories got translated to our biology.


FWIW I do feel like I waited a long time to be born.


--Jesus answered, “Very truly I tell you, no one can enter the kingdom of God unless they are born of water and the Spirit. Flesh gives birth to flesh, but the Spirit gives birth to spirit. You should not be surprised at my saying, ‘You must be born again.’ The wind blows wherever it pleases. You hear its sound, but you cannot tell where it comes from or where it is going. So it is with everyone born of the Spirit.”--


Could you explain what this means and its relevance? Not really sure what this is supposed to mean.


It was kind of cryptic; I suppose I copied it there just to mean whatever the reader thinks it means. But, something along the lines of: much more important than physical birth is spiritual birth.


Being put under anaesthesia—along with some related phenomena around sleep—has led me to the personal conclusion that consciousness is memory. Or at least, memory is a fundamental requirement for what I consider consciousness. If I am awake and interacting but forming no memories, my subjective experience is that I have not been conscious.


> One moment I was perfectly awake, and the next moment I was hearing the sounds of people talking around me and I groggily became aware of my doctor getting me to acknowledge him.

Yep. I remember the nurse telling me to count backwards from 10 and I remember being a bit annoyed by it but still doing it. I don't know what number I got knocked out on. I don't even remember getting knocked out. The only thing I remember is hearing voices as I slowly woke up. No memory of anything in between.

> Is consciousness required for intelligent behavior?

No. Computers, machinese, animals, plants can display "intelligent" behavior. They have no consciousness.


I agree with most of what you said, but most animals absolutely have consciousness.


> Computers, Machinese, Animals, plants can display “intelligent” behaviour.

This comment made me think of this article https://link.springer.com/article/10.1007/s00709-020-01550-9


I was skeptical of the article's claims that anesthetized patients may continue to experience consciousness, but this has definitely shaken the foundations of that belief:

>At doses near the unconsciousness threshold, some anesthetics block working memory (20). Thus, patients may fail to respond because they immediately forget what to do. At much lower doses, anesthetics cause profound amnesia. Studies with the isolated forearm technique, in which a tourniquet is applied to the arm before paralysis is induced (to allow the hand to move while the rest of the body is paralyzed), show that patients under general anesthesia can sometimes carry on a conversation using hand signals, but post-operatively deny ever being awake (21). Thus, retrospective oblivion is no proof of unconsciousness.

Edit: there are some sections of this article that could prompt some interesting discussion from the crowd here. For example, from a subsection "Consciousness and integrated information":

>The evidence from anesthesia and sleep states (Fig. 2–3) converges to suggest that loss of consciousness is associated with a breakdown of cortical connectivity and thus of integration, or with a collapse of the repertoire of cortical activity patterns and thus of information (Fig. 2). Why should this be the case? A recent theory suggests a principled reason: information and integration may be the very essence of consciousness (52). Classically, information is the reduction of uncertainty among alternatives: when a coin falls on one of its two sides, it provides 1 bit of information, whereas a die falling on one of six faces provides ~2.6 bits. But then having any conscious experience, even one of pure darkness, must be extraordinarily informative, since we could have had countless other experiences instead (think of all the frames of every possible movie). Having any experience is like throwing a die with a trillion faces and identifying which number came up (Fig. 2). On the other hand, every experience is an integrated whole that cannot be subdivided into independent components. For example, with an intact brain you cannot experience the left half of the visual field independently of the right half, or visual shapes independently of their color. In other words, the die of experience is a single one throwing multiple dice and combining the numbers will not do.


Many years ago, I received a mild sedative while undergoing an endoscopy via my throat. Apparently, that's not a pleasant experience. I say apparently because I have no memory of it other than asking the nurse when they were going to start ... after the procedure was completed. I remember getting injected with the stuff and I remember me asking that question because I was getting bored just lying there. I don't remember losing consciousness, being asleep, or waking up, or anything like that. It's just a gap in my memory while they did their thing. Amazing stuff. I'm assuming I was conscious and responsive throughout.

I had proper surgery a few days later which involved being knocked out for two hours or so. That's a whole different situation. You start counting down and you are gone within a few seconds.


I've had an endoscopy with no sedatives/anesthetics etc. It was definitely not fun but doable. As soon as the scope went down my throat I went into panic mode. My heart rate was through the roof, and I couldn't stop retching. But after it passed that initial gag reflex point, it settled down. The nurse holding my hand holding my hand soothed me as well.

Then I got up, walked to my car and drove myself home with my brain at 100% (albeit with more adrenaline and cortisol than normal).


The drug they typically give to erase your memory is Midazolam.

You can give someone a small dose of Midazolam, they might report feeling a little dizzy, or say they feel like they’ve had a few drinks, but they will have absolutely no recall of the experience, despite interacting like a slightly tipsy “conscious person” - I like how they call it “conscious sedation” - most people end up believing they were unconscious.


Right, midazolam (aka versed) is a common one. So is propofol (colloquially known as "milk of amnesia").

I've read some horror stories online about people having postoperative nightmares about what they experienced while on the operating table while under versed, so I was really afraid to take it when I went under general anesthesia myself.. but I've had it a bunch of times now, and never experienced anything like that myself.

My postoperative amnesia has been complete, and I'm happy for that.

On the other hand, I still worry about what I might have experienced that I don't remember.


Falling asleep at night after an upper endoscopy, I had a vague recollection of the feeling of retching during the procedure. I know that they try to sedate as lightly as possible, so maybe they undershot slightly in my case. I think I had asked the anesthesiologist what they gave me when I was waking up, because I felt particularly hung over, and they said it was propofol.


I really hope they verify these anaesthetics by doing brain scans during surgery to check whether any pain areas in the brain are activated.


At least for some anesthetics, the pain centers will be active while under anesthesia. Rather, interconnectivity between brain areas is disrupted, preventing your conscious experience of pain. Whether or not that is a case of amnesia regarding what you experienced, or a genuine lack of experience, is an open question. Although I firmly believe that brain wide integration is necessary for consciousness and so there is no experience of pain.


I guess another test would be to try to interrupt connectivity without amnesia or paralysis. This could lead to evidence for pain.


I wonder if the pain sensation in your brain , despite not being connected consciously to your experience, has some lingering after effects. Like the engine room of a ship springing a leak but the bridge is just fine and never noticed it when it happened.


Great song by Gaylord, Milk of Amnesia:

https://youtube.com/watch?v=cFfQILesiXE&feature=share7


I got a small dose of that for my colonoscopy. I was 100 % there, looking at the camera feed, complying with the doctor's orders, I even remember being a little surprised that I feel and remember everything. An hour later, sipping a milkshake at McDonald's I realized I didn't remember the procedure at all. Just these disjoint flashes of consciousness, the sound of the machine, the feeling of the tool moving around, but no real coherent story. Interesting experience.


Startup idea: video content moderation service for big social media companies with moderators given medically supervised Midazolam; no more high turnover due to PTSD and no counseling needed


The TV show Severance feels as though it's along those lines of thinking. Separate your work self from your personal self....completely


Propofol is also common with endoscopy, and sometimes combinations of drugs, so it's hard to say what GP received.

There's also an interesting thing where the anesthesia you get is likely to be very different for the same procedure if you get the procedure at a hospital versus an outpatient clinic. Because anesthesia at a hospital is typically a department with influence, and turf wars happen.


If you think the tourniquet technique sounds interesting you should read up on “awake craniotomies” - another very interesting area of anaesthesia and consciousness.

Ultimately in anaesthesia, the mind may not recall the experience but the body still feels it. You see this in unparalysed body’s that flinch when they’re cut, or in fully paralysed bodies that signal pain in an observable increase in heart rate and blood pressure. However, most the time, people are also given substantial analgesics to reduce their likelihood of experiencing pain, but the point I’m trying to make is an unconscious person is still able to feel pain of they have not been given adequate pain relief.


What if the experience of pain is separate to the experience of heart rate rising and blood pressure rising?

Like, you get a cut, and the trigger is the "damage" that then triggers pain and the heart rate rising. It's not the pain itself that triggers the heart rate but the damage. Maybe? Idk


I wouldn't be surprised if it was a little of both.


I've read about something similar called split brain where there can be separate consciousness in the brain and maybe elsewhere. Interesting experiments have been done on it and it just all seems so weird. Very tricky figuring out this consciousness thing from the inside.


"But then having any conscious experience, even one of pure darkness, must be extraordinarily informative, since we could have had countless other experiences instead (think of all the frames of every possible movie)."

It is worth asking why this argument does not also apply events like the die-rolling case, and it is because the state of the world immediately after the event is strongly constrained by its state immediately before.

The argument quoted above tacitly assumes there are no such prior constraints in the case of consciousness, but this does not seem to be supportable. If it were so, it would seem that our minds would be constantly taking a random walk through a vast number of possibilities, and it seems inconceivable that there could be consciousness in that case.

As '(52)' in the longer passage is a reference to an early paper by Tononi on his Integrated Information Theory (IIT), I think it is worth pointing out that this argument does not support IIT specifically, or more strongly than any other theory consistent with the premise that the current state of one's mind strongly constrains what happens next.


A childhood fear of mine was that every time I lost consciousness my mind could be going through the worst torture imaginable and I just don't remember it. I still wonder if I'm having horrific nightmares every time I wake up sweaty.


I had the same fear too growing up. I found peace with it and stopped thinking about for many years until now, when I realized that practically it wouldn't affect my waking life if it actually did happen, if I had no memory of it at all, so there would be no use worrying about it.


Being an oldie, I have occasional colonoscopies in which I've always been anesthetized. My most recent one was a couple of years back. I'm not sure what happened, but during the procedure (after evidently going under), I was fully conscious of everything that was going on. I couldn't move and had no feeling for what was happening, but I could hear the doctors talk and could tell what was happening. It was much like a dream, but the most vivid dream one could imagine.


And I'm not an expert in this area, but my understanding is that during a colonoscopy they use a level of anesthesia called "conscious sedation", and the drugs they use also tend to have strong amnesia-inducing properties.

Anesthesia for surgery is more complicated and involves a cocktail of different drugs, administered in a particular sequence, tending to include paralytic drugs as well as special inhaled drugs that we don't even really know how they work (eg sevoflurane). It amounts to a much deeper state of anesthesia than the conscious sedation used in things like GI endoscopy and wisdom tooth extraction.

IANAA (I Am Not An Anesthesiologist) but I like to read about stuff like this and ask my doctors about it whenever it comes up for me.


I had a somewhat similar experience when I got my wisdom teeth out recently.

I consciously remember saying "Wow, this is working way faster than I thought it would" right before the dental assistant told me to go to sleep if I felt like it.

I have some memories of the surgery happening, like my head being jerked around when they pulled teeth out, but it was painless. Immediately after the surgery after I "woke up" I felt like I could remember quite a bit of the procedure but that feeling faded after some time and it all felt like a dream.


Have to say my experience of propofol was pretty interesting.

It's this milky substance that is injected directly into your blood. The action seems to be super fast and super deep.

I remember the anesthetist talking to me while doing it, I think it's standard practice, and I pretty much vanished mid-sentence. As in, not just "I feel like I'm sleeping" that you get each morning or evening in bed, more like "time just vanished" kind of way.

Very hard to explain the speed with which you drop from awake to sort of sleeping to "there is no me". The way back is a bit slower but harder to pinpoint, but I knew something was different in the recovery room.


"Very hard to explain the speed with which you drop from awake to sort of sleeping to "there is no me". The way back is a bit slower but harder to pinpoint, but I knew something was different in the recovery room."

There was no perception of speed in my case.

I just have a distinct memory of a mask being put over my mouth and nose and the nurse/doctor telling me to count upwards... and then I was in the recovery room.

No gap, no memory of going under or anything that happened in between. It's like the intervening time didn't happen.

Much like waking up from a dreamless sleep.


> No gap, no memory of going under or anything that happened in between. It's like the intervening time didn't happen.

I had the same experience 2 weeks ago when being put under with propofol.

They asked me to hold a mask against my face and to start counting and then that's it, I woke up in recovery.

It was like I blinked and the whole thing was over.

Did not feel anything 'coming on' or like I was loosing consciousness, I was fully conscious and aware of all my surroundings, and then, bang, was in recovery.

Strange experience.


I've been thinking a lot about my same experience. I also spoke to her as it was kicking in.

It was humbling. Like a computer being turned off, and then back on an hour later.

For that time, I didn't exist. It helped convince me that after death there is just.... Nothing.


This seems like an assertion based on incomplete evidence. Not saying you're indelibly wrong, but presuming there is such a thing, one would think it's infallible, and thus you're not going to accidentally slip into paradise before your allotted time.


Most ideas about life after death are based on the assumption that because we have consciousness, it can't just "stop existing" as a true nothingness. Ask someone to picture that, and they picture a black void that they still experience.

So it seems sensible to me that General Aneasthesia would feel quite unique in that regard (I have experience it myself) - one moment you're here, the next you're waking up. You don't dream, you don't feel like time has passed at all, it's just kind of a blink and then you're somewhere else.

And that's it - "true nothingness". It's the closest you can get to not existing while still being able to come back.


I think a good way to imagine non-existence it is to ask people to think about how they feel about the time before they were born. It's better than that idea of a black void that some get, and it tends to better illustrate the concept that the world once existed without you experiencing it, and so there is nothing weird about it existing again without you experiencing it in any way.


I think this is a cheat.

If instead we found someone who (for whatever reason) believed that they just popped into existence, as if from a puff of smoke, at the age of 3... and we did your thought exercise but instead told them "think back to the 3 years before you manifested"...

To that person, it might well seem like a clever idea. "Hey I didn't exist then, but I don't really experience or remember that nothingness!"

Except they did exist, may well have been conversational even for the last part of it, etc.

There's no good way from first principles for me to be sure the same isn't true of myself before my birth. I don't expect much after my death, but like everyone else I'm just going to have to wait and see (or, wait and not see, as the case may be).


Oh, I'm not claiming I've solved the mystery of what happens after death!

I'm just saying this may be a good way to help someone visualize better what it even means to say that consciousness just stops, not that it somehow proves that is what happens.


I wonder if going under anesthesia is different though due to the time involved. Like, if you're under for 4 hours, you'll feel like no time has passed. But what about 4 days? Or 4 months?

If death is infinite, to really compare death and anesthesia, we'd need to experience being under for longer.


I had surgery last year and I believe I was out for a few hours. when I woke up I could definitely sense that some amount of time had had passed. I haven't felt that sensation during quicker surgeries so maybe our perception of how quickly time passes is changed and slowed down?


Perhaps our consciousness existed in some spiritual way, but no memories got translated to our biology.


You ever walk into a room and forget why you walked in?

I think changes in perspective break memory.

Greater changes mean greater breakage.

Walking into another room is a change. sleeping, dying, Weird drugs. Those are also changes.

Also, there is a degree of breakability/flexibility, inherent to the person. Depending on various stuff.

And there are ways to become more flexible too. Less prone to breaking. This leads to phenomena like "lucid dreaming".


It seems that when you die, memory and the capacity for thought are irretrievably lost. It seems that consciousness is separate from memory and thinking. What happens to consciousness when we die? It's reasonable to think the same thing happens as when we're unconscious. It seems that being unconscious (through sleep or aneasthetic or some other method) is a reversible death. Maybe consciousness is always there, but experiencing something else, just not our brains?


Why would consciousness be different from memory and thinking? I don't think there's even an agreement on what consciousness IS. Or even, is consciousness even a thing? Or is it a label we give ourselves to separate us from other things?


That seems a somewhat hasty assumption, given at no point did you die.


No, they lost themselves completely to something much less destructive than death. If a chemical causes a complete cessation of self it only follows that's brain death would as well, unless propofol somehow affects your ethereal spirit more effectively than your brain literally decomposing.


While I don't intend to make any actual assertions in either direction, I do feel bound to note that the experience of being anesthetized isn't really incompatible with a concept of souls and of ensoulment. After all, under anesthesia there remains something to "come back" to. When dead, not so much.


My theory is that death is different than taking propofol or some other anesthesia because while you are taking those drugs, your cells are still living. Your brain cells are not dieing and producing decomposition chemicals everywhere.

I think that's in the difference. When dead, your cells all decompose and start releasing and forming decomposition compounds which flood your brain and body. Not to mention your cells becoming fundamentally broken and unable to do their jobs.

My theory is that there's a fundamental system in the brain that gives us our sense of self gives us our sense of "this is me, and that is everything else". And that slowly goes away to the point where you can't distinguish the difference between self and other and you become everything.


Interestingly, entheogens as a category of drug have been defined by the same ablation of self/other boundary that you describe. (Please don't ask me for a citation! I remember seeing this definition in the context of MDMA's inclusion in the category, but have no idea where.)


That's a beautiful way of looking at the experience of being conscious of self, thank you for sharing it. I'm going to keep that in mind.


Not sure what exactly they gave me, but I had 2 cases:

(1) In a hospital, when after injection with a syringe, I lay for maybe 5-15 minutes, wondering when it would show any effect and what would happen, if I tried to stay away, before it was suddenly lights out.

(2) Another one at a doctor for a check of something, which was injected into the bloodstream directly without a syringe, but a drip/line. That one affected me very quickly and I remember suddenly having a weird smell in my nose, saying something like "hm smells funny" and then I was out. It was an interesting experience. Not a bad one. Not a good one. Just interesting.

Afterwards I did not have memory of either one. But at the second one, I remember, that it took time, before I could reliably stand and walk and I sat down for a while, thinking, that the feeling was also "funny". At the first one it was an operation after which one usually does not walk and stays in bed for a while. Also the one for the operation must have lasted much longer, since I woke up much later, afaik.


I've been administered propofol before, and I've experienced syncope before. They're a great deal alike. If anything, the most notable difference is that propofol takes long enough you can feel it coming on, which is more than I've ever been able to say for old-fashioned passing out.

I don't find anything to choose between the experience of coming out of it and that of waking somewhat slowly from deep, dreamless sleep, except incidentally that one typically falls asleep and wakes up in the same place. The discontinuity of awareness "feels" the same in both cases. For that matter, going under propofol feels a lot like falling asleep while deeply exhausted, except without the actual exhaustion, which is in my view the strangest thing about it.

In my mostly misspent youth, and long prior to my first experience of general anesthesia, I once had occasion to try what was then and might still be called "whippets", or the inhalation of carbon dioxide for theoretically recreational purposes. Stupid and pointless as this is and was, in hindsight it was much as if one were under propofol able to pause just before the point of entering discontinuity of conscious experience. That was deeply unpleasant in a way I find impossible to explain, but enough so that if forced to choose I believe I'd prefer to undergo surgery again. As with being around heroin addicts whose habit one does not share, it's the sort of thing that should quickly, and quite rightly, lead one to decide that a scene where this is ordinary is a scene where one does not wish to belong.


> carbon dioxide

You probably mean nitrous oxide (N₂O). Both are sold in small aluminum canisters for culinary use. CO₂ is acidic and is quite unpleasant to inhale. N₂O is listed in the article (Table 1) as one of the inhalant anesthetics.

I had the experience of going through both IV general anesthesia (presumably propofonol) and syncope in the last two weeks and for me propofonol was much faster getting in and out of: like falling asleep and I woke pleasantly remembering a dream. Syncope for me was much harsher: tunnel vision as a passed out and I came by initially not remembering where or who I was, like my brain did a cold boot.


You're right, it was nitrous oxide. I gather also the name originates from a trademark "Whip-its" under which these "charger" canisters are sold.

This was probably all explained to me at the time, but mainly what I remember of it is a large balloon followed by spending an indefinite but subjectively very long time in a clangingly silent gray hell.


Michael Jackson was known to refer to propofol as "Milk of Amnesia". He loved his propofol very much. He loved it unto death. He had a private physician who didn't ask a lot of questions or put up a lot of objections to Michael's idiosyncrasies.


Gosh, scary. I still remember watching the news the day he was still alive, talking about how half his body was hot and the other half was cold. The human body scares me.


but during sleeping time also kind of vanishes? Seems like propofol skips the being-tired stage that precedes sleep but otherwise..


I often remember my dreams. My wife is always amazed that I remember so many of them (she hardly remembers any). But I never ever remembered a single "dream" I made under anaesthesia.

I wonder if people who remember many of their dreams have different experience? To me it's pretty much like GP: mid sentence and then boom, gone.


there is also retrograde amnesia. people live and feel. then suffer amnesia and can't remember having lived and felt. doesn't mean they didn't live and feel, though.


I usually don't remember my dreams (and if I do, memories are usually very vague). However, I still have a sense of time passing when I sleep - ie: I wake up in the morning and I feel like some number of hours have passed since I went to sleep, even if I can't remember what happened during those hours.

I've been under general anaesthesia once, and there was no sense of time passing. One instant I was in the OR, the next I was in the PACU. If you'd asked me, I'd have had no way of telling you if I'd been out for 20 minutes or 8 hours (I was out for about three).


Yes, that is what felt so strange. It's like you're awake, you feel a bit of cold in your arm, then you're waking up. No in between, just snap fingers and you are elsewhere.


Sleeping usually retains the feeling of time passing. Propofol is just a complete removal of consciousness in my opinion the same as just being dead


This was also my propofol experience. The doctor injected a tiny bit by accident before I had to sign a form and I felt so removed from consciousness it was weird. Then he pushed the rest and next instant of time I was in the recovery room but it felt like the best sleep I’ve ever had in my life. No wonder people get addicted to it


I’m not sure if I had the same drug, but I had the same experience, but I also remember the feeling of progressively vanishing in a couple of seconds starting from the injection site progressing upwards to my head probably because the drug took a bit of time to circulate.


I've gone under a few times as a child. I remember it as just closing my eyes and then opening them. No in-between. Absolutely no dreams, memories, or anything. Just an instant time shift ahead for however long i was under.


Don't let all the physiology distract you from the HN-relevant information theory(?) in the `Consciousness and Integrated Information` section near the end:

  A recent theory suggests a principled reason: information and integration may be the very essence of consciousness. Classically, information is the reduction of uncertainty among alternatives: when a coin falls on one of its two sides, it provides 1 bit of information, whereas a die falling on one of six faces provides ~2.6 bits. But then having any conscious experience, even one of pure darkness, must be extraordinarily informative, since we could have had countless other experiences instead (think of all the frames of every possible movie). Having any experience is like throwing a die with a trillion faces and identifying which number came up. On the other hand, every experience is an integrated whole that cannot be subdivided into independent components.

  Less metaphorically, the theory claims that the level of consciousness of a physical system is related to the repertoire of different states (information) that can be discriminated by the system as a whole (integration). A measure of integrated information, called phi (Φ), can be used to quantify the information generated when a system enters one particular state of its repertoire, above and beyond the information generated independently by its parts. In practice, Φ can only be measured rigorously for small, simulated systems. However, empirical measures could be devised to evaluate integrated information on the basis of EEG data, resting functional connectivity, or TMS-evoked responses.


An argument why IIT is nonsense: https://scottaaronson.blog/?p=1799


I think the amnesiac effect of many anaesthestics also tricks us into thinking we go totally unconscious under their effects. I've been operated on several times and sustained near life threatening injuries in the past. I can't remember any of the most painful bits, despite occasionally making conversation / looking around with my eyes open. I'm thankful I can't remember.


I had to be operated while conscious but lightly sedated and I remember bits of it. I remember being told that I had to receive an injection around the orbit of my eye with anesthesia and that it would be painful. I remember being calm about it. I also remember that it was very painful but I felt ok with that. I was like: "it's true, it's really painful".

So maybe it's like that always, even if you don't remember. You sometimes feel pain, but since you are sedated, you don't feel stressed about the pain.


A more worrying possibility is that we suffer terribly under anesthesia, but we can't move or scream because our muscles are temporarily paralyzed, and we can't remember the ordeal because our memory gets wiped.


well, that's not just a worrying possibility [1]. bears the question what was going wrong?

a) that you woke up

b) that you remember having woken up

1: https://www.asahq.org/madeforthismoment/preparing-for-surger...


> The condition, called anesthesia awareness (waking up) during surgery, means the patient can recall their surroundings, or an event related to the surgery, while under general anesthesia.

That's something else though. You could be very aware but forget it.


i don't see why this is sth else.


The website talks about remembering being conscious. But you could be conscious without remembering it later, which was what I originally talked about.


No, that wouldn't usually happen. I've had surgery a few times. What they do is monitor your brain activity and pulse rate to see if your are coming out of anesthesia for some reason. If you were suffering, at the very least your pulse would go up, and they will notice.


That sounds reassuring.


Indeed there is several monitors that can be used to measure “awareness” including entropy, bi-spectral index, and SEDline to name a few. SEDline is my personal favourite as you can see when a patient has complete “burst suppressions” - this is a total absence of brain activity at all and has been associated with post anesthetic delirium particularly in elderly patients.


Oh now that sounds worrying again. Maybe there is a trade-off between being spared pain and losing IQ points.


I don’t think so.


What's the difference then between "experiencing it but not remembering" and "never experiencing it at all?"

Effectively it's the same.


The experiencing part.


Severance explores a similar topic.


Just looked it up, it appears to be a TV show.


Yup. The premise is that you can have your work self "severed" from your home self.

This means that you've essentially become two different people. It's really good if you're into that sort of dark sci fi stuff.


The premise is that you create a separate person with a separate "memory bank" that lives in your body. That person can suffer a lot but "vanish" after work hours (or in this case surgery with anesthesia) and "you" you may or may not care about their suffering. Should you? That's the question.


There was some interesting studies and such I read around anesthetics + memory blockers that still lead to some subconscious exhibition of PTSD. I don't have them on hand but there was some interesting stuff on how potentially we may still remember traumatic surgeries even if we can't explicitly recall them.

That's why there's been a push towards refining sedation techniques further both to reduce the odds of a patient being conscious during surgery and also to reduce the amount of stress it can put on the body.


It would make sense if the mechanism for PTSD is unrelated to the mechanism for episodic memory which are disrupted by memory blockers


I would absolutely love to read these studies!


I found the first one I was talking about [1] which talks about possible memory encoding while unconscious.

[1] https://pubmed.ncbi.nlm.nih.gov/17900016/


Thank you! That is awesome :)


Yes I got a hint of this the first time I went under, my first memory of being awake was back at home, on my sofa, upstairs.

As my mom tells it, i walked myself to the car, behaved like a weirdo with my feet on the dashboard (never done this once in my life).. sprinted out the car, up the stairs, fell, got up.. went to the sofa, and fell asleep for a few hours.

So clearly I was not out for the entire period I had amnesia for. It makes me wonder what parts I was unaware of vs what parts I was aware but memory wiped.


I think a fundamental aspect to consciousness is memory recall to be honest.

This line of thought gets kind of philosophical though because I often can’t recall my drive home from work - does that mean I wasn’t conscious? No! - highway hypnosis is yet another interesting consciousness (or lack of) phenomenon.


Consciousness is a continuum not, a binary state. There are also subconscious processes at work.

After a bit of practice you don't have to think about all the intricate actions you have to take to drive a car or ride a bike. Consciously you can focus on something else while other parts of you are aware of your surroundings and what you need to do to drive/ride.

Same with simply walking. Unless you're in unfamiliar/dangerous terrain, you normally don't have to think about where you're going to put your feet or your balance. Your subconscious awareness and competence takes care of all that.

It doesn't mean you're not aware or conscious on some level and to some degree, though.


> does that mean I wasn’t conscious? No!

Counterpoint: Yes! Why not? You didn't need to be conscious for it... I think that's how deep habits work. How would you define conscious in a way that you could count that?


This shows that memory isn't required for consciousness. We can be fully conscious while forgetting everything after a few minutes or less. Actually, when we look at a highly detailed photo or video this is pretty standard: We forget most finer details within seconds.


I think there is a difference between an already conscious being losing their ability to recall memories vs never having the ability in the first place. Maybe you can technically maintain the state of consciousness without forming new memories once you've already achieved it (for example people with Alzheimer's/other forms of dementia, but that is up for debate how "conscious" they are during it's most advanced stages), but getting to the point of consciousness in the first place doesn't really seem possible without some kind of ability to refer back to previous experiences.


Is there something special about memory, or is it just another tool for consciousness?

It seems like consciousness is the conductor and puts to use whatever it has access to (motor function, sensory inputs, memory). Any of those can be significantly impaired (limbs/senses lost, imperfect memory) and the conductor simply adapts and focuses on what remains.


Are people with superior memories able to attain higher consciousness than others? If not and it is a binary, conscious or not conscious, then what is the minimal ability in memory required to attain it?

In my view, memory is not a requirement for consciousness. It is required for learning a language to communicate about your consciousness but not for the process itself. You can be fully aware of yourself and your surroundings without referring to previous experience.


That’s actually a good point. For anyone to truly feel conscious they need to have memory otherwise it would feel as if you just keep waking up


Is it worth noting that the term “consciousness” has multiple forms?

Consciousness, having existential feedback and wakefulness are separate forms.

We are existential feedback consciousness whether or not we have awareness (or memory), and we are awake conscious when we have continuity of awareness.

The one word has two closely related functional contexts.


Wakefulness is necessarily integrative at the level of the whole individual. Global Workspace Theory, and all that.

Is the same true of existential feedback consciousness? I'm very interested in hierarchical models where low level consciousness might operate independently, but be bound together into an individual's conscious experience.


Existential feedback consciousness is happening in every neuron, every neural cluster, every brain region, and finally competing to produce the illusion of waking consciousness.

Some, yet not all are perceptually aware of multiple scopes of awareness competing for coherence (“idea in the back of the mind”, “on the tip of the tongue”, intuition, etc.)

Consciousness is actually so diverse we can train and automate outside of the scope of awareness (reflexive techniques such as learning language, martial arts, setting intentions, etc.)

We often refer to this as “subconscious”, yet this is more truly the “consciousness” we are most interested in.


Any books to read or papers to suggest on this?


Every part of what I have described has been somewhere mentioned or eluded to by scientific exploration, yet not one single discussion or exposition likely exists which ties these topics together in a gratifying or coherent way.

Leading trends incorrectly describe consciousness as an “emergent phenomenon” in “some region”, yet separately (and much earlier) the discussion of microtubules as a possible substrate for quantum interaction. I do not believe we possess the technology to observe or replicate how this might work, considering we cannot hypothesize or test how quantum interaction can be reliably maintained at body temperature (the answer I believe to be insulated layering, a properly of 2D crystallography, and mass aggregation.) that electrochemical perturbance occurs during neural firing is an inherent proposition of physics.

Similarly on each other item I have mentioned such as what we call “subconscious” being key to understand underlying “consciousness”, or the programmability of neurological complexities, they seem almost self apparent yet cannot quite be conjectured by formalism.

The luxury of citizen science/philosophy contends with the range of comfortably integrating speculations.


We're in the dark ages wrt consciousness.

We might as well have multiple overlapping consciousnesses, some of which may experience pain during anaesthesia.


Steven Strogatz had Emery Brown of MIT on his Quanta-produced podcast to discuss anaesthesia and particularly its differences from typical sleep:

https://www.quantamagazine.org/emery-brown-and-the-truth-abo...


WOW this is an amazing article, thanks for posting.

As an aside, this popped out to me: the brain implements an algorithm not unsimilar to the TCP congestion window algo!! Perhaps I’m reading into it too much but that’s just terribly interesting.

  At intermediate anesthetic concentrations, neurons begin oscillating, roughly once a second, between a depolarized up-state and a hyperpolarized down-state (11). The up-state is similar to the sustained depolarization of wakefulness. The down-state shows complete cessation of synaptic activity for a tenth of a second or more, after which neurons revert to another up-state. As anesthetic doses increase, the up-state turns to a short burst and the down-state becomes progressively longer.


I see it more like a NES system that has a bad connection to the cartridge - constantly rebooting, trying to get that signal from the copy protection chip.


The book, "After: A Doctor Explores What Near-Death Experiences Reveal about Life and Beyond" (Bruce Greyson M.D.), explores this subject.


"...Thus, retrospective oblivion is no proof of unconsciousness". I have always found this prospect terrifying.


In sleep, there is a state in which we have a inner mental narrative, with subjective sensations, thoughts, and emotions. And we usually forget it even if we remember at all; most of it never enters the awareness of our wake selves.


Ok, Tyler Durden.


The topic, but not this exception, is touched on in “Your Brain: Who's in Control? | Full Documentary | NOVA | PBS“ Episode 2 of a two-part series, premiered May 24, 2023. Both episodes are fascinating and eye opening.

08:36 Anesthesia and the Brain

https://youtu.be/yQ6VOOd73MA

https://www.pbs.org/wgbh/nova/video/your-brain-whos-in-contr...


This is another nod to the non-duality philosophy, which I think deserves more attention.

This conversation between Rupert Spira and Donald Hoffman talks about the unconscious in a way very relevant to this research. Very interesting to hear both sides and interesting that these revelations back Rupert's point that consciousness is always there on some level: https://www.youtube.com/watch?v=9rWqUBqprk8


I had surgery under general anesthesia for the first time in my life a year or two back, and it was very enlightening.

Specifically, most people who have general anesthesia talk about how strangely different it was from sleeping.

It was virtually identical to what my sleep has been like most of my life. I went out then I came back.

I was groggy longer than usual waking up, but that was about the only difference.

I almost never remember dreams, historically. I lay down, go out in < 5 minutes, then get up when something wakes me.

That seems to be a rare experience, so I figure outta worth mentioning.

Also interesting is that I've been taking atomoxetine for the past few months, and one of the effects has been that I don't sleep nearly as deeply and now remember dreams regularly. My nights are much longer and I don't like it.


When I was a kid I had my appendix removed and I woke up during operation. My vision was foggy but I could hear 20% of what was being said. I asked the surgeon "should I scream?".

He shouted and waved his finger at me "Do not scream! Do not scream!"

I went back to sleep and woke up in a hospital bed.


Good god, that's horrifying. I hope you're ok now.


don't get me wrong nothing hurt. I was just counscious.


I woke up during an endoscopy when I was young (4/5 years). I have a pretty vivid memory of that one single moment when I came too, and the doctors/nurses panicking a bit when they realized I was conscious. It ended pretty quickly when they gave me more of whatever the anesthesia was.


Seeing the authors of this paper, I am reminded of some of my favorite conversations with Gulio Tononi on Closer to Truth, about the nature and constructs of consciousness.

https://www.youtube.com/watch?v=uiS5i2d9zBA


I've never liked Propofol and the hours of dopiness it induces post-op. I did my last colonoscopy with no anesthesia. It was only mildly uncomfortable and pretty interesting - the doctor acted as tour guide. The I got up and went home fully awake. I recommend it.


what do you do if your doctor refuses to do the procedure w/o anesthesia? find another doctor i guess?


Probably - I'd wonder why they'd refuse. Most insurance (AFAIK) won't cover the anesthesia as 'not medically necessary'.


There's a very good Radiolab episode that discusses this:

https://radiolab.org/podcast/anesthesia


I think about consciousness a lot, and therefore, like to read about it.


Anaesthesia is more dangerous and impactful than commonly realized. These chemicals and medicine need to be more strictly controlled.




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