A systems view of biological health

Section 2: Theory

22 : Feedback loops and conversation theory

This work is licensed under CC BY-SA 4.0 : also see my full Copyright statement.

Life is one giant self-referential communication feedback loop. These loops:

• translate between different forms of information and different meanings, and

• tend to self-stabilise – so need constant recalibration to a shifting external world

The basic "cell" of communication is a more considered and expanded version of

Input → Response

- that was devised by Gordon Pask (shown opposite). There is a constant flow of this kind of conversational exchange between each adjacent cell, within each organ, between organs, between local and systemic organisational and functional structures, between the tissues and the microbiome, and between the body-inside-the-skin and the Living world it is part of.

These are really self-referential "Sense, Meaning-making, Response" loops. Pask added a critical factor – that living systems exhibit "amicity" – i.e. they want[1] to participate in meaningful communication. Note that meaning-making does not have to be congruent or deliberate between individual units, because each has its own sphere of interest and function, and very often it is the waste by-product or incidental in one that is meaning-ful to the next. So the stretch receptors in a muscle do not need to know the function of the movement, or even that they are participating in movement – only that their world has been stretched and that their function is to signal that event, not back to the muscle, but back to the spinal nerve roots, cerebellum and motor cortex.

There are several ways in which this relationship is formulated in normal ways of thinking that are far too restrictive. One is to think that "it’s all neurology" (Figure, right) – which is true to a degree, but that’s certainly not the whole story. For one, Glia (immune cells) provide a functional substrate to neural tissue in much the same way that fungi provide a substrate to tree roots. But also – there are (e.g.) feedback loops between various systems of the body and the mitochondria in which the mitochondria might occasionally have the greatest say.

So a common error is to think of the body as being run by a hierarchical command structure rather like an army – which it is very definitely not. Another simplification is to equate the two sides of the conversation (a classic duality), whereas conversations within ecosystems (including the human body) are often between a container and a semi-autonomous subunit of that container, leading to what Varela termed a { Star-duality }. This kind of quasi-duality is a situation where there is not one because the subunit may exhibit very significant autonomy, but also not two because the subunit cannot be extracted or removed or disconnected and either it or the container continue to be viable.

Furthermore, conversations can be thought of as translations , in that meaning-making occurs in one participant, is then converted (translated) into a response, which is then detected by another participant which then performs further meaning-making and so further translates into another response … and so on. Thus, information in one medium rapidly cascades and propagates into other information streams, physical locations and time/frequency domains. Your body-mind being a contained organism, information does not only diverge, but also returns and converges. Homeostasis could therefore be considered to be the act of finding the minimum information entropy – the arrangement by which information discordance is minimised and harmonic relationships are maximised across different kinds of information mediums, time frames (frequency domains), physical structures and the "external" environment.

In all these feedback loops – including the ones connected to the outside world, the buck stops at a cognitive level, because the cognitive-rational level of your body-mind takes the decisions around which everything else has to organise itself. So whilst it’s true that your body "tells" you it is hungry, you usually have some capacity to decide when you eat and what you eat, and how much you eat. This may be interfered with socially (Ramadan, school meal times, poverty), but nevertheless the cognitive layer has the potential capacity to decide so long as a decision is possible.

There is quite a strong tendency in popularised science to describe biological systems in ways that imply hard (instead of loose) coupling and therefore that the body is an automaton. DNA is one such topic – and it has been thought for some time that DNA is a direct 1:1 code, one piece of DNA transcribing one protein, and as such "only" a protein-making machine. It is now understood that there are a relatively small number of DNA sequences (about 20,000) that produce recognised proteins. But some sequences code for many different proteins, and many other sequences produce smaller "building blocks". The specific output from DNA is then assembled according to instructions that have come from feedback loops further "up" - meaning that whilst DNA provides some basic function, its expression (methylation) and how expression is then converted into organic molecules is a higher level process. Does DNA produce the cell, or vice versa? Well, it seems that the answer is – neither and both. It is the total system of communication that organises "up" to the "form", growing into a recognisable organism, and "down" to determine what building blocks are available. You might be surprised that the nucleus of the cell is connected to (and is a part of) the connective tissue network (fascia). Mechanical tension in the whole-body fascial network affect the tension on the surface of the cell nucleus, and directly affect gene expression – a specific example of "Form Follows Function, Function Follows Form".

If you consider Pask’s communication cell with respect to the conversations between cognitive mind and body, this presents a clear working relationship.