Damasio’s theory of consciousness

Antonio Damasio is a neuroscientist and neurologist who has published a number of theories about how the brain and mind work.  Unlike many theories of mind, his are thoroughly grounded in neuroanatomy.

Central to Damasio’s theory of consciousness is the idea of biological value, that which helps in preserving homeostasis, which of course aids in survival.  This survival impulse is shared by all life, even the simplest single celled organisms.  Brains are systems evolved to preserve homeostasis and ensure survival.

In Damasio’s view, consciousness centers on the self.  While he doesn’t see the self as an illusion, he doesn’t see it as a static thing either, but rather a process evolved to manage homeostasis.  He uses the analogy of a symphony.  When the symphony begins, it doesn’t have a conductor.  But as it plays, the conductor comes into existence and then takes control of the symphony.  The self comes into being in the brain in layers: the proto-self, the core self, and the autobiographical self.

The proto-self’s formation begins in the brainstem, although in healthy humans the insular cortex, an area in the fold between the parietal and temporal lobe, is also involved.  The brainstem is constantly receiving updates from the body, from the peripheral nervous system.  It uses these signals to construct an image map of the body.  The lower portions of the brainstem are focused on the viscera: the heart, digestive tract, etc.  The higher portions construct an image of the musculoskeletal body.

The brain is vitally concerned with and tightly bound to the body.  It is constantly receiving updates of its body image map from every corner of the body proper, initiating various changes, and then receiving the results of those changes in a tight resonance loop with the body that never ends, until death.  And the most primal level of this resonance starts in the brainstem.

The brainstem is phylogenetically ancient, and many simple animals get along without much else.  From the brainstem arise primordial feelings.  It maintains its active model of the body, the chief object of its concern, and has the basic foundations of homeostasis management.

One interesting area of evidence that Damasio uses for this part of the theory are children born with a birth defect: hydranencephaly, that is without a cerebrum, with only a brainstem and hypothalamus.  These children have a kind of proto-sentience somewhat similar to normal newborns, although they are never able to move beyond that cognitive stage.  Yet they appear to enjoy sensations, music, have favorite caregivers, and generally have a sort of primal existence.

On top of the proto-self is the core self.  The core self is the momentary self.  It exists in “pulses.”  It comes into existence when the proto-self perceives objects and how those objects relate to the body.  Is the object food?  A predator or some other kind of threat?  Another body like ours?  Something else?

When I first read Damasio’s description of this core self concept, I wondered what he was talking about?  Then I realized that he was addressing primal first person experience, the state of a self experiencing perceptions and what those perceptions immediately mean to the self, to the body.  Or perhaps more accurately, he is addressing the feeling of first person experience.

The brainstem is heavily involved in generating the core self, but it isn’t the main show.  Damasio hypothesizes that the main coordinator may be the thalamus, but all areas seem to participate, from the brainstem, the thalamus, and the cerebral cortex.

On top of the core self is the autobiographical self.  This is the self that comes into existence as the organism lives its life.  It is heavily dependent on memories, along with the projections it makes for the future.

And here we get to what I find to be the most interesting aspects of Damasio’s theory.  It’s an explanation for how perception, memory, imagination, and decisions get made in the brain.  To begin with, Damasio describes two types of brain areas: image making areas, and dispositional areas.  The dispositional areas are, evolutionarily, far more ancient, but even the brainstem has low resolution image making portions.  We are conscious of a portion of the processing that happens in the image areas, but never conscious of what happens in the dispositional areas.

To understand the image making areas, consider the process of seeing something.  The photons hitting the photoreceptors on your retina form a pattern which trigger signals up the optic nerve to the brain.  When the signals reach the vision processing centers, patterns form, models, image maps built from the cumulative signals coming in.  In other words, visual images form.

If we hear a sound, a similar audio image will be formed in the audio processing centers, and so on for all the other senses.  This  happens with greater resolution in the neocortex than in the sub-cortical areas, but it happens in many areas of the brain, all in the regions closest to where the sensory pathways come in.

Further from the sensory pathway areas are the dispositional portions.  These are the areas that drive memory, imagination, emotions, and actions.  For memory, Damasio’s view is that we never store actual images.  We only store what the image means to us, the associations between the aspects of the image, the associations between various images from the different senses, and the associations between combinations of images, emotions and possible actions.  From these associations, we are able to later recreate a version of the original image, although it’s never as detailed as the original since the recreated version doesn’t have the sensory data stream coming in.

This works through a concept Damasio calls CDZs (convergence divergence zones).  When images form, the patterns propagate from the image areas into the dispositional areas.  The image of a doughnut may come in at the same time as the smell of doughnuts and then the taste.  All of the cascading signals from the senses converge at a certain neural circuit, a zone.  If this happens repeatedly, or perhaps once with strong emotions firing, synapses become strengthened.

Later, when only one of these signals come in, it may trigger a reverse signal flow, initiating a process called retroactivation, that causes a version of the patterns that initially formed the convergence to reappear in the image areas.  So the smell of doughnuts may trigger memories of the sight and taste of doughnuts.

CDZs exist in hierarchies.  The lowest hierarchies receive inputs from image areas and can both output back to the those image areas as well as upstream to next level of CDZs.  The CDZ hierarchies are clustered in regions Damasio calls CDRegions, which interconnect with each other.  Damasio envisions CDZs existing in the “many thousands”, but there being a few dozen CDRegions.

The multisensory doughnut example above would be a fairly high level CDZ.  In reality, every complex image is itself a galaxy of CDZs.  The visual of a bear is a full range of associations, such as attributes of the bear’s shape, color, activity, etc.  The image of the bear that probably popped in your mind while reading the previous sentence was, according to Damasio, recreated from the bear related CDZs in your brain being triggered by the word “bear.”

But CDZs aren’t just for generating images.  They also generate actions.  (Image generation could itself be considered a type of action.)  That action can be to trigger the release of hormones, to initiate muscle action, or maybe to inhibit action arising from another cluster of CDZs.  CDZs are, of course, the physical manifestation of associations, and the mind works through associations.

I wasn’t sure of usage rights so I didn’t reproduce them here, but here are some diagrams showing the CDZ hierarchies in action.  It starts with a stimulus to part of the network, and ends with the whole associative network being activated and generating the images.

CDRegions are probably created from genetic information, as are many primordial CDZs, but most CDZs get created from experience, from learning.

Incidentally, CDZs also trigger emotions, which Damasio sees as self contained autonomous actions.  He makes a distinction that had never occurred to me, the one between having an emotion, and the feeling of the emotion.  When something triggers an emotion, it happens.  Hormones are released, heart rate is altered, the brain goes into a state prepared for a certain type of cognition.

Earlier in evolutionary history, this immediately led to action, but in more intelligent animals it’s a two step process.  The second step for us is that we feel the emotion though the body image, which influences our inclinations, but leaves us with the power to alter the inclined actions, a capability the autobiographical self contributes toward and a possibly adaptive reason for its existence.

Neocortex lobes Image credit: Sebastian023 via Wikipedia
Neocortex lobes
Image credit: Sebastian023 via Wikipedia

The CDRegions interlink with each other, but the linking appears to converge heavily in a region Damasio calls the PMCs (posteromedial cortices), an unusual name referring to a region that, judging by his diagrams, appear to be in the middle portions of the parietal lobe, and the posterior cingulate cortex underneath.  It is here that Damasio thinks the autobiographical self may live.  It might be best thought of as a CDRegion at the center of a galaxy of CDRegions.

There’s obviously a lot here, and I’ve just given a very surface level summary.  As I noted above, I find the CDZ and CDRegion part of this theory to be the most interesting.  (In reality, they were published as a separate theory, predating Damasio’s theories of self by several years, or at least their publication.)  The power of the CDZ and CDRegion concepts are that they may give us insights into the architecture of the mind.

One possible flaw I see in this overall framework is that it’s more a theory of self than of consciousness in particular.  It doesn’t seem to address the difference between what happens in our conscious experience and what happens subconsciously, or of the experience of experience.  (There are other scientific theories that do, and they’re not necessarily incompatible with Damasio’s theories.)

I also suspect that the division between image forming areas and dispositional areas in the brain isn’t nearly as clean as Damasio implies.  It’s almost certainly more of a spectrum, with early sensory cortices perhaps being more image forming and other regions gradually becoming more dispositional the further they are from the sensory pathways.

There’s also a danger here of viewing the images as passively created by the senses, when in reality, particularly for vision, an enormous amount of active modeling is taking place from the retina on back to the brain, with even our immediate perceptions heavily influenced by preexisting associations.

Still, there’s a lot here that strikes me as very plausible.  Damasio makes no pretense of his theories being the final word, only that they add possible explanations of what is happening, and I think they definitely do that.

All of the information in this post came from Damasio’s book ‘Self Comes to Mind‘.  A quick warning: I didn’t find this to be easy reading.  Damasio often discusses neuroanatomy in detail and assumes the reader can follow along.  And his style is very verbose, often taking a long time to make a fairly basic point.  Still, if you’re interested in how the mind works, I found it worth the effort.

If you have the time, here’s Damasio’s TED talk on consciousness:

h/t amanimal for recommending the book!

30 thoughts on “Damasio’s theory of consciousness

  1. I have read some of Damasio’s books. I find the core assertion of defending homeostasis as somewhat suspect though. Homeostasis is not something created by living organisms. It is a physical phenomenon rooted in physics and chemistry and is something that life bootstrapped upon. And at its root homeostasis gives us stromatolites, not consciousness. Is very puzzling but grander philosophical structures have been built on flimsier foundations.

    Liked by 2 people

    1. Wouldn’t you say it is true that every aspect of life is rooted in physics and chemistry that life bootstrapped upon?

      I don’t think Damasio is asserting that only systems with brains (or even only living systems) have homeostasis, only that the need to maintain it is shared by all living organisms, and that brains are one evolutionary solution for preserving it.

      I do think Damasio might focus too much on homeostasis as the origin of behavior. Certainly it’s a major component, probably the largest, but reproduction is crucial and, in mammals and birds, so is care for kin.

      Liked by 1 person

      1. They look quite similar when things are going well. It doesn’t make a difference then, if you think of physiology acting like the thermostat in your house, i.e. working to maintain a certain status quo.
        But it is hard to explain pathophysiology in terms of the thermostat model. Things like shock don’t simply rectify themselves when a stressor is removed.
        Likewise, biological systems don’t necessarily struggle to get back to a set point until they fail. They can stabilize at other points, albeit often temporarily.
        Maybe the sort of ‘meta-neurology’ in question works differently, and more like a thermostat. I am skeptical, though. My guess is that it ends up being more a jazz quartet than a symphony.

        Liked by 2 people

        1. It’s worth watching some Demasio videos – on one he actually says he things homeostasis is not a helpful word coz it implies static which the system is anything but. But he says it is pretty much impossible to introduce better words to a wide audience so he reluctantly lives with a commonly used but ultimately limited one.


          1. Thanks for commenting.

            I’ve recently started hearing the word “allostasis” as a substitute for “homeostasis”. The idea is that homeostasis is reactive while allostasis is predictive. They have the same goals, but allostasis recognizes there’s more in the system than reactions.


      2. Homeostasis and balanced equilibrium. It seems that homeostasis is a vector pointing to an ideal state. It seems we constantly and usually experience near-equilibrium states. Constant homeostasis right lose the dynamics of a living organism whereas the near-equilibrium state provides a energy gradient for actions. Like keithnoback’s comment. It seems . . . lol

        Liked by 1 person

        1. Thanks dug.

          Interestingly, the Webster definition seems to cover both conceptions:

          “a relatively stable state of equilibrium or a tendency toward such a state between the different but interdependent elements or groups of elements of an organism, population, or group”

          Further down, they give a medical definition:

          “the maintenance of relatively stable internal physiological conditions (as body temperature or the pH of blood) in higher animals under fluctuating environmental conditions; also : the process of maintaining a stable psychological state in the individual under varying psychological pressures or stable social conditions in a group under varying social, environmental, or political factors”


          I don’t have a strong opinion on any of this, but it seems like the word gets used in a variety of ways.


  2. Thank you for a very informative review. I believe the human brain is too complicated for the human mind to grasp. But, at least, we should try.

    The neuro-anatomy of 100 billion neurons and 100 trillion synapses approaches the complexity of many galaxies – ineffable.

    Does Damasio address the issue of how qualia come about? How and from what is our experience of color produced, for example?

    Liked by 2 people

    1. Thanks Liam. I actually think there are good reasons to be optimistic that we’ll eventually understand the brain. We already know a lot more than most people realize. But there’s still a long road ahead.

      Damasio did discuss qualia in the book, but it’s difficult to do justice to it in brief. I think he sees it as deeply rooted in the will to live. If perception is to be effective in leading an organism to make effective decisions, then we can ask how should they feel? For example, the vividness of red may be due to the fact that most primates eat fruit and ripe fruit on the African savanna is often red. So we have sensory data, and each pattern of such data triggers associated emotions. All of this is related to the self, effectively the first person in first person experience.

      Explaining qualia is difficult. It’s an ineffable intuition about experience, but no explanation is likely to be intuitive. I’m increasingly starting to see Michael Graziano’s point that maybe, instead of focusing on the origin of qualia itself, we should be focusing on the origin of the feeling of qualia.

      Liked by 1 person

  3. Fantastic synopsis, for which many thanks. I like the stress on the importance of feeling within this theory of consciousness. Too often it seems to get relegated in favour of language (symbolism) and algorithmic computation as preconditions. Given the stress on feeling, then I was a little surprised not to hear anything on the role of proprioception in facilitating the sense of agency. Does that come up in the book, Mike?

    Liked by 1 person

    1. Thanks Hariod!

      I agree on the language / symbolism preoccupation. A lot of computationists think that brain processing happens in a language of its own, sometimes called “mentalese.” But I personally see it as very unlikely. The language of thought is the language of neurons and synapses. Of course, in reality the language of technological computation is (currently) transistor states, but we build layers of abstraction (languages) between the raw machine and us to make it easier to work with. Evolution had no such incentive to do that with brains.

      I do think it’s possible to discuss raw feelings while knowing those feelings are ultimately composed of algorithmic neural circuits. But it definitely isn’t Damasio’s inclination to discuss it in those terms.

      On proprioception, I just did a search on the text. He only briefly mentions it (once inline and a couple of times in the backnotes), which is a bit surprising since that seems like it would be a significant aspect of the body image map.

      Liked by 1 person

    1. Thanks Mark.

      I considered reading ‘The Feeling…’, but ‘Self…’ was available on Kindle and was 10 years newer, so I figured it would be more up to date. Based on that review (thanks!), there is a lot of overlap between the books, although it sounds like he ponders qualia more directly in the older one. The same neurological stories mentioned in the review are in ‘Self…’. That said, I’d imagine you can find ‘The Feeling…’ online somewhere; Amazon shows used hardcovers from 1 cent up.

      Liked by 1 person

  4. Antonio Damasio’s TED talk is excellent. He has three good points.
    One, human-like consciousness (HLC) is the product of brain-mapping.
    Two, brain stem (not frontal lobe) is the portal for HLC.
    Three, many other animals have similar brain stem like human’s; that is, other animals also have consciousness although not as sharp as ours.

    But his work has no connection to the ‘FUNDAMENTAL’ laws, the laws of nature (physics). Here is the missing parts.
    One, definition of ‘intelligence’:
    Necessary condition: there is a ‘counting’ device (counting strews, abacus or Turing computer).
    Sufficient condition: the ability to distinguish self from others.

    Two, definition of ‘consciousness’:
    Necessary condition: the ability to distinguish self from others.
    Necessary condition: there is a ‘counting’ device (counting strews, abacus or Turing computer).

    Obviously, {intelligence and consciousness} are closely related but definitely different. So, their implementations can be different via different machines.

    So, I agree that HLC is implemented via the brain stem while the intelligence is produced in the frontal lobe (see http://www.prequark.org/inte001.htm ).

    For the naive explanation for the selfness is the Pauli’s exclusion principle that every Fermion carries a unique ID number while the whole explanation is more complicated. For the universal counting device, see http://www.prequark.org/Biolife.htm ).

    Liked by 1 person

    1. Hi Tienzen. Good hearing from you.

      I think you might be overstating the role of the brainstem, at least in Damasio’s theories. Yes, it all starts there, but for human like consciousness, even the proto-self requires the insular cortex, core consciousness requires the thalamus and early sensory cortical areas, and autobiographical consciousness, the full human level experience, requires large portions of the neocortex.

      The brainstem does provide a sort of proto-experience, which may resemble the experience of insects and other relatively less intelligent creatures. But the hydranencephalics I mentioned are profoundly limited in their cognitive abilities, or even in their movement abilities. In other words, they aren’t us minus the intelligence. They’re missing a substantial part of the (healthy) human experience.

      Relating consciousness to fundamental physics seems similar to Penrose’s approach, although Penrose is looking for a new physics. I think all non-duallists agree that it will involve classical physics and chemistry, but I’m not sure we need to go lower to account for mental processing (although who knows what future evidence may reveal).


  5. My favorite philosopher of mind is David Chalmers, who makes a distinction between the hard problem and the easy problem of consciousness: the easy problem being “how does the mind work”, and the hard problem being “why is a mind conscious”. I think that Damasio’s theory is one of the most interesting ideas about solving the easy problem, but I’m not sure if it really gets at the hard one, because all that he establishes is that the brain may be capable of recalling memory in the form of feelings when presented with some stimulus (e.g. a donut), which is just a theory about the software and hardware of the brain. But a true theory of consciousness must be about why software and hardware is capable of having the “experience of experience”, as you put it so well, in the first place. Do you think it will ever be possible to solve the hard problem with science?

    Liked by 1 person

    1. Greetings Kyle.

      I think there are two answers to your question at different levels. Will science ever solve the hard problem? No, I don’t believe it will.

      But I suspect it will show that the hard problem isn’t the problem we think it is. More specifically, I think it will explain why we have the intuition, the feeling of the hard problem. One possible answer along these lines is Michael Graziano’s Attention Schema Theory, which I’ve addressed it other posts: https://selfawarepatterns.com/2014/10/16/the-attention-schema-theory-of-consciousness-deserves-your-attention/
      There are other similar metacognitive theories, all envisioning awareness as a feedback mechanism, the mind modeling its own operations, that provide similar explanations.

      In that sense, the hard problem of consciousness may become like the hard problem of light in the 17th century. No one could understand how the color white came into existence, how it became “clean” and pure. The answer is that it doesn’t. The brain simply translates the onslaught of all colors as white. White doesn’t exist in nature (of course, neither does any other color, but white doesn’t exist even as a particular range of wavelengths like the other colors do).

      Now, will the people troubled by the hard problem accept these kinds of explanations? My personal experience is that most won’t, which is why I gave my initial answer above. Many regard such explanations as essentially “explaining away” the problem. I don’t see it that way, but I can understand why many people do.


      1. Hey thanks for responding!

        I’ve read a couple more of your posts on consciousness, and I think I see where you’re coming from. But I still get hung up on Chalmers’ idea of the “philosophical zombie”, a thing that behaves like it’s conscious but has no “inner life”. I suppose that the version of the hard problem that confounds me the most is: can we ever know if anyone/thing else isn’t a philosophical zombie?

        I agree that studying the mechanisms of the brain is much more interesting and fruitful than pondering the hard problem, but I still think that the problem exists. I’m not sure if I follow the metaphor of white light , because while the question ,”how is light purified of color” assumes certain characteristics of light that are now known to be false, i.e that color is an impurity, the hard problem only assumes two things that I think are pretty hard to deny.

        You (whoever reads this) has an inner life
        It is not obvious that other individuals experience any inner life

        So to solve the problem, we either need to establish that the concept of “having an inner life” is somehow an illusion, or that it is obvious that others have one too, which I think would be hard because every individual can only verify their own consciousness.

        I think that it is clear that the human brain is nothing more than an information-processing device (however unfamiliar its methods may be), and that the reason I think thoughts and feel feelings is because of my physical, material brain. And I am deeply skeptical about panpsychism. I know that even my own fascination with the hard problem itself comes from the deterministic and unconscious atoms that bounce around my skull, but I’m still not sure if I can ever be certain that I’m not the only person who’s really alive. Ya know?

        I really hope I don’t sound like some hyper-metaphysical nutcase. I’ve never seriously considered the possibility that other people are zombies, but I just don’t see any way to explain my own experiential reality in purely physical terms.

        Liked by 1 person

        1. No, I think you’re right that we can never know beyond any shadow of doubt that anyone else is conscious, that everyone beside ourselves aren’t philosophical zombies. We assume other humans have an experience similar to ours because we all seem like similar systems, but the further we move beyond that (other primate species, mammals, vertebrates, machines, etc) the more doubt about how similar their experience is to ours.

          That being said, I think it helps to ask, from an evolutionary perspective, why do we have an inner life? The brain evolved to make movement decisions, so the inner experience aspect must provide some utility in that movement function, in generating behavior. So, if we encounter another system that behaves in a similar enough fashion to us, it makes sense to conclude that the other system has at least an equivalent experience.

          Of course, it may well be possible to use an alternate data processing model to produce the same behavior, which could imply a behavioral zombie. But that strikes me as being chauvinistic against alternate forms of consciousness. If the system we think of as a zombie can produce equivalent behavior, then it must have some mechanism functionally equivalent to ours in production of that behavior; it must have some form of consciousness, albeit one that might be very alien.

          On the inner life being an illusion, I don’t know that we actually do need it to be. We only need some of our intuitions about it to be wrong. That’s where the color white comes in. Our intuitions about its purity are wrong, so worrying about whatever problems arise from that is not productive.

          Our internal self model of our mind is simplistic, mainly because there was no evolutionary need for it to be more accurate. This leads to a discrepancy between that simplistic model and objective data about the brain. It’s this discrepancy, I think, that causes the feeling of the hard problem.

          We’ll never banish that feeling. (At least, not without altering the brain.) And those troubled by it will likely never find explanations about simplistic internal models satisfying, which is what keeps leading me to the conclusion that we’ll never “solve” the hard problem, only explain it.


Your thoughts?

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.