Brain As Emulator

I can’t remember how I first came across Robert Pepperell’s Consciousness as a Physical Process Caused by the Organization of Energy in the Brain. At the time, I remember the paper struck me as interesting and made some good points but, at the same time, didn’t actually seem to deliver a lot that was new. It was like looking at a large three dimensional artwork from a different angle. The object of vision wasn’t substantially changed; it just looked a little different.

One idea that did stick with me was the idea of the brain as difference engine.

In light of these mechanisms, the energy-hungry brain might be understood as a kind of ‘difference engine’ that works by actuating complex patterns of motion (action potential propagation) and tension (antagonistic pushes and pulls between forces) at various spatiotemporal scales. Firing rates and electrical potentials vary within neurons, between neurons, between networks of neurons, and between brain regions, so maximizing the differential states the brain undergoes. A decrease in activation, or a reduction in firing rate, can create a differential state just as much as an increase. And, as is indicated by the work of Schölvinck et al. (2008), deactivation may be an energy efficient way for the brain to increase its repertoire of differential states. Maintaining a global E-I balance across spatiotemporal scales, meanwhile, is thought to promote ‘efficient coding’ in sensory and cognitive processing (Zhou and Yu, 2018). All this lends support to the idea, proposed above, that one of the roles of energetic activity in the brain is to efficiently actuate differences of motion and tension that advance the interests of the brain-bearing organism. It is the actualized difference that makes the difference.

The notion of differences in connection with the brain came back to me again when I read recently about the Weber–Fechner law. The law is not quite a law but more like a rule of thumb. Basically it states there is a logarithmic relationship between stimulus and perception. The classic example relates to weight perception. If a weight of 105 g can barely be distinguished from that of 100 g, then if the mass is doubled, the differential threshold needs to be 10 g, so that 210 g can be distinguished from 200 g. The “law” seems to apply to all senses with some minor discrepancies and exceptions.

The oscillatory networks of the brain also seem to act in a similar way to input. Much of the effect of inhibitory neurons is to dampen inputs so that neurons do not fire wildly with each small change in the environment. The result is a brain that mostly is running its own emulation of the world based on its own self-sustaining rhythms that is occasionally incorporating outside input.

Let’s suppose we are walking along a clear, flat, well-paved road with no traffic. Picking up each foot and pushing off into a stride would require almost no input from the outside world or from the brain. A coalescing view of the evolutionary origin of the spinal cord and brain is that they were necessary for locomotion. Central pattern generators are “biological neural circuits that produce rhythmic outputs in the absence of rhythmic input”. The experiments of Thomas Graham Brown in the early twentieth century showed that the basic pattern of stepping can be produced by the spinal cord without the need of descending commands from the cortex. Encountering a stray rock that had been thrown on road might require an adjustment to the stride. At that point the brain would get involved even though the perception of the rock may not rise to the level of awareness.

Back to energy again. It would make sense that evolution would optimally select for lower energy solutions for the brain all else being equal. It requires a lot more energy to take in and assimilate information from the environment than it does to operate with as little information as possible as long the model of the world that the brain is using is good enough for survival. Here we may have the core of what lies behind several different observations.  For one, the idea of Hoffman and others that our model of the world is not likely veridical because it would be too costly energy wise to create a truer model. For another, what Baars and others have pointed out, learning new skills require a lot of energy in the brain because they require the assimilation of a lot of information, but the use of learned skills require less energy and occupies smaller regions of the brain.

The picture that emerges for me is that of a brain that primarily is generating its own model of the world. Into the model, it allows as little information as it needs to function. The brain prefers to operate in a low-energy homeostatic state as much as possible. The brain in effect might prefer to be a zombie. A small rock while we are walking may trigger a small modification of the model. The sudden appearance of large truck coming towards us, however, might require a completely different sort of activity. Quickly attention and resources must be brought to bear on dealing with the truck. Large amounts of information must suddenly be brought into the model. An fMRI of the brain at that time might detect a large spike in nutrient utilization in various parts of the brain as many neurons begin to fire rapidly.

Could we be misunderstanding the spikes in fMRIs that are so often used in neuroscience and consciousness studies? Could the spikes be simply evidence of the attentive process rather than the more low-energy processes that form the foundation of consciousness?

Some would argue the attentive process is consciousness, but then what creates and maintains our model of the world – the visual, auditory, tactile expanse that exists even without attention.

 

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14 Responses to Brain As Emulator

  1. The Webner-Fechner law is interesting. It seems compatible with the idea that our experience is often more of a gist of a scene than all the details of it, unless for some reason we focus on a particular detail. But because the detail is always there when we check, our impression is of a rich detailed scene.

    I don’t know too many people who argue that attention and consciousness are one and the same, although it always comes down to definitions. Attention itself is actually numerous processes operating at different levels. Exogenous “bottom up” reflexive attention can definitely happen unconsciously. It’s how we can drive while daydreaming about something else.

    But endogenous “top down” attention seems much more entangled with attention. It might be that they’re different, but if so, the probability of us being conscious of something is dramatically higher when we attend to it. And inattentional blindness seems to demonstrate that, at least most of the time, what we’re not attending to, we’re not conscious of.

    I think when learning our world model, the new and novel capture our attention, which requires more resources, and so is conscious.

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    • James Cross says:

      “But because the detail is always there when we check, our impression is of a rich detailed scene”.

      Or, it could be that the detail is always there in the emulation.

      There are some that think consciousness and attention cannot be dissociated.

      “The idea that attention is strictly linked to consciousness is not new (James, 1890; Posner, 1994; O’Regan and Noë, 2001). Indeed, the idea is quite intuitive, if we consider what is thought to be one of the main characteristics of attention: its selective power. When we attend to a certain object or part of an object, we are able to isolate it from the other objects or parts, so that our conscious mind is completely and exclusively possessed and “filled” by it (La Berge, 1995). Even though this does not prove that attention is necessary or sufficient for consciousness, it shows that there is a direct connection between attention and consciousness: how we pay attention to the world is highly correlated with how the world appears to us.”

      https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3279725/

      I tend to think there are two types or forms of attention. There is a sort of low-level scanning and assimilation of differences that may or may not result in something reaching awareness. This is low-energy. Then there is a high-energy, more intense assimilation that occurs during learning and when large differences have been detected by the low-level processes. Definitely, some might consider only the second to be attention, but in both cases, detection and assimilation of differences is happening.

      This low-level form has some things in common with the default-mode network; however, the DMN is not usually described like that.

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      • My understanding of the DMN is that it’s activated when we’re engaging in imaginative simulations (daydreaming, etc) not driven by external stimuli. It’s opposite in function to the dorsal attention network, which is active when our focus is on some external task. (It’s interesting that the DMN and DAN appear to be anti-correlated, meaning that only one is active during a conscious episode.)

        I think of the low level stuff as arising up from subcortical regions and mediated by various parietal ones. It’s not one, but several mechanisms. And much of it is responded to by other subcortical mechanisms, which seems like why we’re not always conscious of it.

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        • James Cross says:

          That is pretty much the conventional understanding. However, the DMN seems to encompass so many different things that it seems to be defined only as what the brain does when it does not attend to external stimuli. But it is not entirely clear to me that it is turned off then. See this written in the context of DMN and notice the partially deactivated:

          “These two areas representing the core regions of this network are partially deactivated at times when the subject goes into states of reactive (evoked) activity which is induced by stimulation or during states of active attention necessary for an immediate response to the demands of an environment.”

          And this

          “The endogenous activity is anti-correlated with reactive activity of the brain which is represented by attention systems. If one is active then the other is partially disengaged and vice versa.”

          https://www.sciencedirect.com/science/article/pii/S1053810017300338

          My hunch is that, in fact, it may be the primary NCC. It is anti-correlated with attention systems but it appears to be only partially deactivated. What’s more it engages with many sections of the brain. (BTW the article I reference says it does not involve the thalamus but others do argue that the thalamus is involved among other parts of the brain). I get more the picture of the brain as emulator arising primarily from endogenous activity of the brain but that conscious experience is periodically punctuated with attention activities in response to external stimuli, during learning, and whenever relatively larger amounts of information must be assimilated.

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  2. Steve Ruis says:

    I read an article in Scientific American I believe, that challenged the electric connection between neurons and offered an alternative involve physical connection. Would this not change everything or maybe change nothing? (The same inputs and outputs are allowed for.)

    Liked by 1 person

    • James Cross says:

      I would be interested in seeing the article. Do you have a link? Depending upon the alternative, it could change a lot. But it is hard for me to imagine that all the axons and dendrites in the brain serve no purpose and it seems like both are involved with electrochemical activity. Even though I think EM fields are involved, I don’t think they are the exclusive form of brain connections.

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    • James Cross says:

      Is the article:

      Brain Cells Communicate with Mechanical Pulses, Not Electric Signals

      https://www.scientificamerican.com/article/brain-cells-communicate-with-mechanical-pulses-not-electric-signals/

      It is interesting that there are mechanical pulses associated with neurons firing and that may be impacting some of the behavior of neurons. Whether the mechanical pulses can completely explain everything and turn the electrical pulses into side effects, I’m not sure.

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    • James Cross says:

      I think probably that, if mechanical pulses were the key communication mechanism, it would invalidate the EM field theories unless EM fields were essential to triggering the pulses. BTW I don’t see in the theory what triggers the pulses to start with. With electrical connections the pulses are generated by differences in ions on different sides of the membrane.

      All in all I don’t think the strong form of the theory is likely to be right. That there may be mechanical influences on neural communication might be likely.

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  3. Lee Roetcisoender says:

    James,

    “The picture that emerges for me is that of a brain that primarily is generating its own model of the world. Into the model, it allows as little information as it needs to function. The brain prefers to operate in a low-energy homeostatic state as much as possible. The brain in effect might prefer to be a zombie.”

    I think you nailed it. This would explain why it is so difficult for us to assimilate new ideas or new models of our world. It requires more energy to assimilate them and for the most part, new ideas that result in a new model are not appreciated nor incorporated if the new model does not offer a better schema for survival. Great concept Jame, I like it.

    Peace

    Liked by 1 person

  4. Interesting points. Often, I have pondered about consciousness and awareness, too. What is what and how does it happen. The idea that the brain creates its own emulation of reality is fascinating. This is also the first time I learned the spinal cord can do activities without reaching the brain. I wonder what other processes happen like that.

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    • James Cross says:

      My understanding is that a good deal of motor movement is embedded in cooperative operation of groups of muscles. I think much of body control during bird flight only minimally involves the brain. There are also a large number of fixed action programs that involve the brain but only tangentially. These can be modified and new ones can be learned but the foundations for some of them are inherent in neurology at birth and are ready to used under the right circumstances. These are like repertoires of behavior that get activated when the right signal happens.

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