Epidermis, the 'third brain' (Was Re: Emotions construct the world)

[Joh Orengo EEST]

About two months ago (29.04.18 to be exact), I mentioned an article I read a few years ago about the epidermis possibly being the ‘third brain’. Here’s the article for those of you who are interested.

The abstract:

“The role of the brain includes reception, processing, and transmission of environmental information from sensory organs to the systems of the whole body. Interestingly, the digestive organs have an independent nervous system, which has been called the “second brainâ€?. We propose that the epidermis, which forms the interface between the body and the environment, could be considered a “third brainâ€?, as it contains multiple environmental sensors and a sensory information-processing system, and it generates a variety of hormones and neurotransmitters with the potential to influence whole-body states and emotions. Specifically, epidermal keratinocytes contain sensors of mechanical stress, temperature and chemical stimuli. Furthermore, we have shown that a series of neurotransmitter receptors, which play key roles in the central nervous system and brain, are functionally expressed in keratinocytes. Cultured human keratinocytes can generate structures similar to those seen in the brain. Moreover, all the components of the hypothalamoepituitaryeadrenal (HPA) axis appear to be present in epidermal keratinocytes. Overall, these results are consistent with the hypothesis that the epidermis plays a significant role in adapting whole-body physiology, and also emotional response, to changing environments.”


epidermis as 3rd brain.pdf (696 KB)


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On April 30, 2018 6:02 PM, Angus Jenkinson angus@angusjenkinson.com wrote:

Angus Jenkinson 30.4.18, 15.59

Thanks Joh, I am with you. And thanks for an interesting paper indeed. I am familiar with Noble’s work but far from all that is described within. Thank you also Bruce for your insight:
the necessity to see every level of detail as having its own living control, constrained autonomy.

I have not finished reading the paper; it seems to give intelligent evidence of what I have been convinced of for a long time and offer a particular richness. This is an example
of how focus but without reductionism can be of huge value.



Angus Jenkinson

On 30/04/2018, 14:44, “Bruce Nevin” bnhpct@gmail.com wrote:

[Bruce Nevin 2018-04-30_09:41:34 ET]

Joh Orengo 2018.04.29 0804 EEST –

You posted a copy of Brian J. Ford, “Cellular intelligence”. From the abstract:

Western science … has embraced the notion that every living process can be successfully modeled by a digital computer system. It is argued
here that the essential processes of cognition, response and decision-making inherent in living cells transcend conventional modelling, and microscopic studies of organisms like the shell-building amoebae and the rhodophyte alga Antithamnion reveal a level
of cellular intelligence that is unrecognized by science and is not amenable to computer analysis.

I have critiqued computationalism in linguistics. I am glad to see them affirm that the problem is more pervasive. Computer simulations
of control systems are a kind of computer analysis that they have not considered. As everywhere for PCT, the field is open.

Farther on:

Within those different definitions of intelligence there is one concept on which all seem to focus: the ability to deal constructively with
the unforeseen.

What might they accomplish given the insight that these entities (mitochondria, cells, microorganisms, as well as the higher-order organisms
in which they participate) are living control systems which by means of their ‘behaviors’ control sensed internal and external variables that are important to them.

A metaphorical image comes to mind, the level of water steadily rising, held back at a rim by surface tension. A flood impends.

On Sun, Apr 29, 2018 at 1:16 PM, Joh Orengo joh.orengo@protonmail.com wrote:

[Joh Orengo 2018.04.29 0804 EEST]

This makes sense to me, Bruce. I’ve recently read an article about ‘cellular intelligence’ (attached below) and in the context of what you just wrote, what kind of ‘interactions’ are we talking about here? How complex are the communication
networks that exist between our varied types of cells and the various microbiomes that they coexist with in and on our bodies? In the environment?


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On April 29, 2018 7:58 PM, Bruce Nevin bnhpct@gmail.com wrote:

I thought this went to the list, but it just went to Joh. (Thanks, Joh.)

[Bruce Nevin 2018-04-29_08:51:40 ET]

That is most fascinating, Joh!

My long-standing question is “what’s in it for the cell?” Increased regularization of interactions and ‘justified expectations’ between autonomous organisms has the evolutionary advantage for each of stabilizing the environment (an environment
increasingly characterized by the presence and activities of the others). The tradeoffs are most evident in e.g. the fruiting body of slime molds, but also in the regular demise an replacement of cells. Death is how life improves its vehicles. We can consider
how we participate in that.

On Sun, Apr 29, 2018 at 7:53 AM, Joh Orengo joh.orengo@protonmail.com wrote:

[Joh Orengo 29.04.18 2:36 EEST]

Thank you for that, Angus. The brain is only one part of a much more complex system. To add a bit to what you wrote, there is also the connection between the chemical/hormonal systems with the microbiome that exists in the enteric nervous
system, or the “second brain” of the gut, which influences mood and well being. In addition to that, there is also talk of the microbiome that exists on the surface of the skin or the so-called “third brain” (though I can’t seem to locate the article where
I first read this a few years ago); this microbiome would be the first contact we make with our environment and effect how we perceive the rest of it. A complex and utterly interesting topic.


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On April 26, 2018 2:14 PM, Angus Jenkinson angus@angusjenkinson.com wrote:

[Angus Jenkinson. 11:57. 26.4.18.]

Thanks for a series of comments initiated by yourself, Rupert.

With the danger of repeating points that I’ve made in the past, I think a discussion
of this domain and its function needs to take into account several different interacting sub-elements. I might call these elements systems, except that there is a tendency to transform organic organization into machine organization in the process. The machine
organisation does not replicate the level of fractal and recursive organization, nor the density and complexity of interaction.

At an organic level, and this is particularly true in a human being but is to some
extent common to all mammals, the aspects that involve both “thinkingâ€? and “feelingâ€? (or emotion) are not the same and involve different functional groupings. It is now, for example, very clear that the heart is deeply implicated in emotional states and this
is not simply regulated by the brain. Indeed the heart is in a feedback loop in which it regulates the brain. It is not only the heart. The entire liquid/lymph system, which includes the fluids of the spine and surrounding the brain are connected to the pulsing,
and electromagnetic fields, of the heart.

It’s also important to differentiate between sensory perception and emotional response.
The activity of sensing (intero or extero-perception) must be different from emotion.

With this preamble, I’m not disagreeing that we have to learn to know what is being
experienced and in the process we also construct our mental pictures of the inner and outer worlds (as we do when we try to construct models and formal structures in PCT to explain the behaviour of humans). This is most true for humans who must start off as
a result of neoteny with the highest level of practical ignorance amongst all organisms. The trade-off is that we can carry on learning forever.

Nor am I disagreeing that there are processes in which we observe and adjust according
on the one hand to what we interpret the situation to be and on the other what we would like it to be, controlling for various aspects. Here however is where emotions play a very important role as do other aspects of the organism besides the brain. There is
good evidence that emotions are implicated in this process and equally that this therefore means the heart region, both the neural organisation associated with the hard and the very structural (time phase) dynamics of the functioning of the heart and entire
vascular system. This of course is in turn connected to the breathing and chemical systems that others have referred to (such as the release of endorphins, adrenaline, et cetera)

What I’m pointing towards is a much wider organization distributed organismic process
of responding and controlling in which the brain performs certain specific orchestrating elements rather than all being reduced to it. To the extent that our paradigm or standard models deployed in PCT reduce the richness of the phenomena in order to make
them more simply understood, we ought perhaps to compensate by recognising that the reduction is also a reduction and distortion of accuracy.

Does this make any sense to you?

Angus Jenkinson

On 26/04/2018, 01:14, “Bruce Nevin” bnhpct@gmail.com wrote:

[Bruce Nevin 2018-04-25_20:13:56 ET]

I’m glad you’ve read her book and that you’re going to write to her. I hope “some day” comes sooner rather than later.


On Wed, Apr 25, 2018 at 12:05 PM, Richard Pfau richardhpfau@gmail.com wrote:

[From: Richard Pfau (2018.04.25 12:05 EDT)]

Ref: [From Rupert Young (2018.04.22 16.45)]

RY: Some were asking about emotions recently. Here’s a quite interesting podcast about emotions that might be of interest as it seems fairly compatible with PCT.


RP: The podcast includes an interview with Lisa Feldman Barrett. I find her views persuasive and compatible with PCT as more fully expressed in her book How Emotions are Made: The Secret Life of the Brain (Boston: Houghton Mifflin Harcourt, 2017) except for her view of control theory as predictive processing and the reduction of prediction error rather than the PCT view of how error signals are produced. Otherwise, similarities to PCT abound in her
book: for example, non-linearity (p.32), error (p. 62), parallel processing (p. 63), neural processes that compare sensory input with “predictions” [this being similar to PCT’s comparison of sensory input with “references”](p. 65), interoception (p. 73), the
regulation of action (p.153), and body maintenance (p. 176) – similarities that exist since much of her thinking is based on how control systems operate.

Some day I hope to write to her to both (1) complement her on her persuasive “Theory of Constructed Emotion”, and (2) to present my views on why PCT seems a more persuasive view of control theory processes within our bodies as opposed to the predictive processing
approach that she presents in her book.

But as Rupert points out, her views about emotions seem fairly compatible with PCT.

On Wed, Apr 25, 2018 at 9:48 AM, Bruce Nevin bnhpct@gmail.com wrote:

[Bruce Nevin 2018-04-25_09:48:15 ET]

Our diagrams do not represent the role of associative memory. The closest thing to it is the representation of input functions, especially those at the postulated Category level.
But our canonical diagrams do not represent the complexity of input functions either.

An understanding of associative memory and of the complexity of input functions is crucial for the apparent relationship between the enteroceptive hierarchy (which is said to construct
‘feelings’, sensations of pleasant/unpleasant and arousal/calm) and the behavioral hierarchy (which in its categorizing constructs the perceptions that we call emotions, including fear).


On Wed, Apr 25, 2018 at 2:32 AM, Joh Orengo joh.orengo@protonmail.com wrote:

[From Joh Orengo (2018.04.25.0926 EEST)]

Thanks for the video, Rupert. I haven’t had a chance to listen to it yet, but I look forward to it.

Bruce A., if emotion systems function as control systems, how would you diagram your “fear system” example as a control loop?


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On April 24, 2018 4:33 PM, Bruce Abbott bbabbott@frontier.com wrote:

[From Bruce Abbott (2018.04.22.0935

[Rupert Young (2018.04.22 16.45)]

Some were asking about emotions recently. Here’s a quite interesting podcast about emotions that might be of interest as it seems fairly compatible with PCT.


Thanks, Rupert. I did a one-semester post-doc with the late Jaak Panksepp, who pioneered the field of research
that he labeled “affective neuroscience.â€? Jaak conducted many physiological studies investigating emotional circuits in the rat brain and later became famous in the popular press for his discovery that juvenile rats “laughâ€? when tickled or when “playingâ€?
with other juvenile rats:


I mention this because Jaak proposed seven primal emotional systems in the brain to explain his findings. It
appears that such findings cannot be explained by assuming that emotions are simply the observable effects of changes in control-system error; they are products of complex, specialized “emotionalâ€? circuitry that evolved through natural selection to provide
what usually would be consicered adaptive behavior within a given situation.

Where PCT seems to fit here is that emotion systems appear to function as control systems, each organized toward
achieving particular, identifiable goals. For example, the “fearâ€? system may perceive a situation as dangerous and produce actions that tend to defend or protect against the perceived source of danger. In rats, a perception of danger produces different prewired
behavioral outputs (links to lower systems in the hierarchy [and in the brain!] that carry out the necessary actions), depending on the nature of the perceived danger, such as “freezing,â€? fleeing, or self-defense. In addition to setting references for such
perceptions as the distance between me and the threat (run until the distance is sufficient to remove the perception of threat), or where to run (e.g., to a potentially safe spot), references of certain physiological systems are changed to make the individual
physically ready to do whatever is necessary to counter the threat, e.g., releasing adrenalin into the bloodstream, raising heart rate and blood pressure, initiating sweating (in humans) to carry off excess heat from muscular exertion, and so on. These physiological
changes can themselves be perceived and contribute to the emotional experience.

Although the system itself is the product of genetically-orchestrated development of the brain, learning (reorganization)
soon comes into play, modifying both what is perceived to be dangerous and what particular actions will be carried out under the circumstances. In humans this is carried out to an extreme: A person can learn to perceive as threatening an audience that is
listening to a talk that the person is giving, or a cutting remark (threatening one’s self esteem?). Thus, emotion systems can involve disturbances to perceptions high in the perceptual hierarchy.