Single Neuron Theory Of Consciousness

Science
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Hello, Senior at Port Townsend High School in Washington State here.

I’ve been reading up a bit on theories on consciousness, and I’ve come across a couple that worry me, hoping to get a neuroscientist’s take on this.

I read a presentation given by Dr. Steven Sevush about the single neuron theory of consciousness, stating that consciousness may be created at the single neuron level as pyramidal neurons integrate information in the brain, and I’ve been ruminating and losing a lot of sleep over this for months, thinking about this all day and such, for a few reasons.

For one, if our conscious experience is created by a single neuron or network, and there are other neurons in the brain having simultaneous experiences, wouldn’t that mean that the death of our associated neuron among others in our human bodies dying— would mean the ceasing of ourselves to exist, even if the rest of our body and the plethora of other conscious beings created by other neurons, goes on living without ever knowing at the macroscopic level from the outside?

I read that the adult human brain loses about 190,000 neurons a day. Of course, not all neurons are created equal, as some serve input purposes, some serve output purposes, some special types (like the pyramidal kind) serve both, and others exist mostly for the relaying of information. One might think that a memory cell constantly in use due to its service of core or commonly used memories would be less likely to disappear than a rarely active one. To that extent, one might surmise that a cell with many connections like the pyramidal type, wouldn’t be quick to disappear due to the body’s reliance on the type.

Another separate theory of consciousness that worries me is the idea that our consciousness is of course observably created by cells, and in a non-religious context our soul and existence is merely that of our body. If our consciousness is merely a function of the present group of neurons operating as is, and over time they’re slowly dying off and now and then a new cell or synaptic connections along dendritic trees are being made, would that mean that from the outside our body would continue on existing, our consciousness replaced by another operating as a function of our body?

I don’t mean to enter into an entirely philosophical realm here, so as to waste anyone’s time. I also don’t want to sound like I’ve lost my marbles. But I’ve been inspired by the Allen Institute’s research over the years, and this was the first place I thought to turn over this subject. If any researcher at the institute could answer my question about the single neuron theory of consciousness from a more knowledgeable standpoint of course than myself, I’d be eternally grateful. In fact— I haven’t been able to remain productive as a High School senior for months due to thinking about this all day for hours on end, losing motivation and being constantly exhausted as I’ve tried to obtain closure on this topic. It would mean the world to me if someone could help me out here. Thanks.

-Cameron Rowland

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Hi Cameron,

Here’s a reply from our Chief Scientist, Christof Koch.

While individual neurons in cortex, the outermost layer of the brain, can be amazingly selective – for instance only responding to diverse images or even cartoons of a single individual – such as the famous Jennifer Aniston neurons I co-discovered – there is no evidence that the subjective feeling, he experience associated with any one such percept, thought or memory resides at the level of individual neurons. We know from neurological patients and from neurosurgical stimulation of cortex, that consciousness is associated with large collection of neurons, anywhere from a few 10,000 to perhaps millions or more for a single experience. And yes, the neural networks making up the brain adapt and change (and sometimes die) as we grow up from a fetus into an infant, a child, a teenager, an adult and so on; likewise, so does our consciousness and what we experience. Both the brain as well as the closely associated feelings are two sides of the same coin.

If you wanted to read more on this topic, you can read my popular book The Feeling of Life Itself – Why Consciousness is Widespread But Can’t be Computed (2019).

Best

Christof Koch, PhD
Chief Scientist, MindScope Program, Allen Institute

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First of all, thank you both so much for your time, it means a lot. I greatly appreciate your contributions to modern understandings of the brain and neurobiology, as well as for allowing a layman’s glimpse into the “why’s” of the brain that drive the public to want to know more. As an eighteen year old high school senior, I’ve had no formal education in these areas but have found myself learning and intrigued because of your studies.

I read your beautifully worded and well researched 2019 work, which seemed like a building-on and evolution of your previous insightful books published.

I had to ask, however— not out of doubt of your knowledge in any way, but as a clarification and more so an elaboration on the question posed.

In Steven Sevush’s work, he illustrated the hard problem of consciousness as being illusory within internal observation, as the mind— being an aggregate of neurons, could hold multiple similar conscious experiences at the single neuronal level giving the impression of a single macroscopic consciousness from the outside, due to their nature to work together in creating a single consensus of action in a single human body. The analogy he used was that of a crowd watching fireworks creating a chorused reaction of “oohs and ahs” at the macroscopic level, but being composed of several individual experiences of individual beings reacting to the fireworks independently.

Therefore, though from the outside a living being appears as one conscious experience, internally, such is an illusion as there could be many simultaneous experiences at once.

I didn’t want to believe this, and I still don’t want to, believing that any single neuron— even in the highly interconnected thalamus or claustrum of the human brain wouldn’t hold enough processing power on its own to create a subjective experience of the high-resolution and combined visual, auditory, other sensory, higher thought, and memory processes all at once, given the limits of a single neuron in integrating information from it’s dendrites.

For after all— if Sevush’s theory were true, it could mean that PERHAPS we wouldn’t continue to exist in our own bodies and experience “death” sooner than any of us thought, should the single neuron our experience resides in, die along with the other 190,000 cells we lose in a day.

The reasonable side of me wants to ignore this theory and its arguments— for after all, if it were true, there’s nothing anyone should or could do about it, and we should all be grateful to exist at all in the first place.

But the fact is— I always worked extremely hard and enjoyed doing so— figuring I’d enjoy life even more down the road, being an extremely ambitious person with huge aspirations. Now, believing I might not be around to see it, or even exist tomorrow or years in the future, it’s hard to obtain that same feeling, as well as the novelties of life such as:

“wow, I can’t believe I was really here years ago”

or

“I’m so excited to be in college next year and have a family in the future and reap the rewards of my years of hard work”

It’s the fact that I perceived the single neuron theory of consciousness as non-conflicting with the Integrated Information Theory (IIT), given that single neurons integrate information, that has caused me so much horror as of late, and my obsession to be sure that it wasn’t the case and that I was just overthinking it.

I suppose to summarize— my question is, could a single neuron have the processing power to experience so much in even tenths of a second, to create a conscious experience? And can we be reasonably sure to an extent that this single neuron theory of creating our individual experience isn’t creating an illusion of experience, rather than the entire brain ACTUALLY being a single conscious experience?

I’m sorry to take up so much of your time, and I’m sorry if this wasn’t a very cohesive reply. This whole questioning has been mentally exhausting, and I wish I could forget all of it.

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To better put it— would it be possible that specific activations create a macroscopic looking experience from the outside because of cell activity, while there are several internal conscious entities? The idea would be that specific paths between neurons would activate and bring forth information— say in the case of memories being activated, but according to the single cell consciousness theory, that this information from any source is distributed to all these such “conscious” cells which individually have their own simultaneous experiences. Just wondering if that’s possible.

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Hi Cameron. I´m sorry to read this late, almost 4 months after your last post. Anyway I hope I can give some good ideas on the topic. I am a general surgeon, but I am, as you, very interested in finding a reliable explanation about the conscience phenomenon. So I consider myself somehow an amateur conscience reasercher.

First of all, I can see in your post two main components. The first one is your well developed interest in knowledge about the conscience. And the second one, is the emotional reactions you experience on that knowledge. I think this last one was the most important at the time you posted it, because it produced a good amount of anxiety on you. So, I would like to start first on that.

Besides any hypothesis or proved theory on conscience, the thing of study, the concience, will not change at all. Concience will be the same before and after we already understand it. So, whatever you have experienced untill today will keep being the same. And there’s nothing telling you than this experience will change further. So, after 18 years of conscious life, you already have a really long amount of experience about conscience, although you were not aware of it. And of course, you will keep being able to think about whatever you have become since you were a little girl untill now. And there’s nothig telling you that you won’t be able to do so 40 years latter when you will be 48 years old as I am now. I can still do it now. So I think you and almost every human being are able to do so. I hope this words can releave your anxiety, at least in part.

And now, talking about the first component of your message, your interest about knowledge of the concience, I will give you my oppinion. Of course, I don’t think that a single neuron theory of conscience could be reliable. I haven’t read nothing about this theory; but anyway, a single neuron is not a person, nor a conscious being. If that could be true, even a single amoeba should be able to be conscious. And, untill now, most neuroscientist won’t even think flies or spiders have conscience. We spect only more brain developed animals, like mammals or maybe even octopus, can have conscience. A lonely neuron can not process any information recicling it inside itself. It can receive an inmense amount of imput, but instead of converting them in a complete nuanced picture, it can only produce the most extremely simple output: 0 or 1, nothing or spike (action potential). So, confluece of even millions of millions of single neurons’ conscience would allways be the same, just a simple alternative state of “on” or “off”.

I don’t know if I really understood your second theory worries. But, I do think conscience is just a function of the brain as blood circulation is a function of the hearth and blood vessels. So, I think, and I am well convinced that we die entirely when our brain dies. The only way I can imagine to keep our souls alive after or brains are dead, is to discover a way to transfer our minds and conscience to a mechanical intelligent device. Untill it is not possible, I can not think about any other way. Anyway, I don’t care about that. After death we won’t be able to keep being conscious, but we won’t be able to suffer for that.

I will be glad to read what you think. Best regards.

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the way I like to look at this idea is based on the “fractal geometry of the brain” meaning that many of the properties seen in the brain as a whole are also seen to some degree on the different spatial scales of the brain. according to psychology consciousness implies 3 things:

  1. awareness of one’s environment
  2. awareness of one’s internal state
  3. awareness of one’s actions on the environment

note that individual neurons demonstrate all 3 of these things.

a neuron collects data from the environment and uses it; they are also aware of their own firing via backpropagation (not to be confused with the machine learning definition of the term) and definitely have an awareness of internal state based on the first 2 statements above.

still, i find it difficult to wrap my head around the idea that a single neuron is actually conscious.

but logically, it comes out to be so!

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Hi Cameron,

I am a researcher of consciousness in Nanjing, China.

It’s very impressive to know your thoughts and questions. I think you are giving one critical question about the theory of consciousness: what the real relationship between consciousness and neuron is. For this, our team has a quite different answer— Consciousness is not from neuron, though our mental activities involve the nervous system to give off conscious experience.

We assume that nature has the MFEs (More Fundamental Element) that couple to show as material and consciousness, and the brain has a CNS (central nervous system)-independent consciousness system that couples to give off the consciousness signals, with their three excitation levels to show as memory, sub-consciousness, and subjective consciousness. As consciousness is not from neurons, the method to measure consciousness via NCC (neural correlates of consciousness) is to find out participants with the same kinds of consciousness systems. And make them to produce paralleled “conscious information processes” to filtrate out the “noise” neural activities, to obtain the “real” NCC data. Examining the property of consciousness may advance not only neuroscience and physics, but also cognitive science and AI technology.

We believe to measure the content of consciousness is vital for the theory of consciousness or neuroscience. So, we postulate the brain has two subsystems as the CNS and the consciousness system, and put brain science into three theories: two theories about the two subsystems and one theory about their interaction (the theory of NCC). In this way, we try to put the hard problem of consciousness into two parts: the theory of NCC and the theory of the consciousness system.

We see this method to measure consciousness is in no contradiction with the IIT theory or GNW theory, and it’s only provided an additional logical concern to filtrate the “noise” data in the measurement. Maybe I could have your opinion about this since I see so serious logical reasoning in your words. And I admire your elegant writing so much.

Hopefully, I could have more chance to talk with you.

Thanks so much for your inspiring question.

Jason Ma

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Hi Cameron,

Do you think if neuronal cell is only a tool of conscious experience, then we could more easily to see that one single neuron can do the same work as a group of neuron do?

I have an empirical logical reasoning why conscious experience is independent of neurons, and it is in three aspects: the reaction time, the interaction of memories, and the stability of memories.

  1. We see conscious experience is almost simultaneous, and this is what neuron cell can not, either single or in a group;

  2. If one piece of memory is carried by a group of neurons, either electromagnetic or biochemical, either cellular or molecular level, the interactions among those memories would be spatially complex and tend to be chaos here and there, which lead to information chaos in our brain. But this seems really seldom happen.

  3. If memory or mental activities is primarily electromagnetic or biochemical, we will see a really bad stability of them, because we know those two types of signals so well and they are so unstable.

From above three points, that’s why we reasoning neurons are only a tool of consciousness, such as the work of TV set for the TV programs.

Besides, if we may assume those living creatures without neurons are conscious, then we shall suppose conscious experience is independent of neurons. And that’s why we had followed Neutral Monism to developing a model system of all nature to be the framework of all sciences to explain everything, especially consciousness, because Neutral Monism says that there is a neutral element which being developed to material and consciousnesss in two different ways, so neuron and conscious experience are separate.

Sorry again for my poor writing skills.

Jason

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Hi, thank you for your efforts to ease my mind on this topic. I appreciate the insight and your shared interest in the subject, and time you’ve taken to write here.

I still find the problem that this line of reasoning doesn’t eliminate the possibility that consciousness and our experience isn’t the product of a single cell for the following reasons:

  1. The “conscious” experience our mind and body experiences every day (and even reads and writes about on this forum) and the feedback we speak and write could be— just the macroscopic, observable behavior of us human beings from the outside, not necessarily by any means inherently the same thing as the subjective, conscious, experience we actually feel, even if the two (the feeling and the observable behavior) are correlated.

  2. We haven’t ruled out that a single neuron, being capable of receiving such an immense amount of input in such short amounts of time from so many neuronal sources, and THOSE neuron’s source’s,

doesn’t create, through the reception and integration of all these INPUTS, a conscious experience inside themselves. Which we are currently feeling.

If you think about it, every milli- and deci- second, we are experiencing signals from the nerves around our body- pressure, heat, pain, an immense amount of information in vision, hearing, smell and other senses, and obviously cognitive signals from higher and lower sources of thinking in our brain.

It really comes down to this:

Do we know how many signals and synaptic processes all these feelings happening at once would take from a magnitude perspective, and do we KNOW for certain that a single neuron wouldn’t be able to process this all at once? After all, if the experience of consciousness itself is observably correlated with electrical activity in the brain, how do we know that it’s necessarily resultant from LARGE structures of neurons working together, and not just the same kinds of activity existing on a smaller scale within the structure of a single neuron and a signal passing through it?

Many researchers who have responded to this thread mention that their observations of conscious experience correlate with simultaneous waves of activity across the brain, but how do they know it isn’t just unfathomable numbers of neurons all experiencing subjective experiences independently, all at the same time? After all, it’s the same electrical activity circulating through brain structures - whether at the individual or group level, supposedly responsible for consciousness itself right?

As a side note- I’ve come to peace more so with the subject, often choosing when possible to completely forget and ignore it at times, but I keep coming back to it. Honestly, the quality of my life would marketably improve given an answer on the subject from some higher power or time traveler with the answer, but finding this such answer has become less urgent and a less anxious endeavor through emotional exhaustion and philosophy, a year now into the future of my life since posing this original question.

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Upon further research of the subject, I’ve come to the conclusion that as explained on page 18 of the link to Steven Sevush’s paper listed at the bottom of this text box, that denial upon testing of the existence of

“lateral PFC neuron’s (existence) that respond to conjoint input from the full complement of sensory, emotional, and mnemonic stimuli that comprise VR-conscious experience”

-would almost completely eliminate the possibility of consciousness as we know it being explained by the Single Neuron Theory of consciousness (SNT).

Being a college freshman without the resources, contacts, or wherewithal to find studies surrounding these cells, I was wondering if anyone here on the Allen Institutes forum would happen to know where information surrounding these cells or studies on these cells could be found, or knew the answer to this burning question. I certainly couldn’t find such info upon a simple google search myself.

I’d also recommend reading the paper, its a deep, logical, fascinating read.

Thanks for your time, anyone who sees this!