The brain is overrated: a look at cognition in slime mould

Historical, scientific and philosophical adventure into the nature of consciousness seems to have, nine times out of ten, made the assumption that cognition should be explored within the kingdom of animalia. This top down approach seeks to derive a mechanism for consciousness from that which we already know, rather than from first principles of computation. That is understandable: it is difficult for us to imagine consciousness without those components that comprise our consciousness. 

These components are the layers of neural feedback we get from systems across the body: they overlap, interconnect, and crucially, they are coordinated. All of this is controlled by an organ that someone less cynical might call “mystical” – the brain. We are obsessed with the brain; it is to physiology what quantum mechanics is to physics… click-bait. Bang the prefix “neuro” before pretty much any noun and you have a shiny new product ready to go into the Argos catalogue (does that even exist anymore) – see the NeuroGolf Band or NeuroDrinks or NeuroBliss. They all sound very clever don’t they. While it is true that we have been able to isolate various coordinative centres in the brain, and it is likely that they contribute to bringing about the unified picture that makes up our consciousness, I posit that our inability to understand the very mechanisms that cause conscious experience comes from this obsession with an organ that may be less critical than we think. 

Image credit: Bernard Spragg, via Flickr

I have been fascinated by this weird substance, slime mould, for some time now. If you’re not aware, it is exactly what it says on the tin: a type of mould, that looks like slime. But what sets these autopoietic (self-replicating) protista apart from their seemingly dumb cousins is an incredible ability to process information, store it and make decisions. Based on the traditional model of cognition, you need a nervous system for that. In fact it was only in 2012 at the Francis Crick Memorial Conference in Cambridge, led by an almost Avengers level line up, that it was declared that non-human organisms could even have consciousness. 

These autopoetic protista have an incredible ability to process information, store it, and make decisions.

Slime mould has no signalling platform at all akin to a nervous system. So what can this mouldy messiah do? Well, its problem solving ability is really quite remarkable, on a level that potentially only humans and computers are able to match. A very simple experiment involves creating a maze with an oat flake in the very centre – the slime mould will fill the maze quickly and subsequently compute what the most efficient root to the centre is. The mould will then only grow in this path – solving the maze. That’s cool, but realistically the vast majority of humans would solve the maze quicker than the mould. However, increase the complexity of the problem and it’s a whole different story.  

The Japanese railway system is much revered across the globe. It boasts a rail map that optimises efficiency across the nation, linking all of the major cities. If you built a map of Japanese cities using oat flakes, and set a lump of slime mould where Tokyo is, the mould does something genuinely incredible. It links the cities with tracts of mould in a pattern that is almost identical to the Japanese rail map – the most efficient route between them. What took a crack team of Japanese rail-engineers decades takes the mould mere hours. 

What we see here is a brilliant example of computation at the most basic level. But, without the nervous systems of the human, and without the processing power of the computer, how does it work? Well, while slime mould doesn’t have explicit neurons or wires, it does have something that harnesses the same concept. It has a calcium ion gradient-dependent metabolic process: nutrient rich areas of the mould map increase the frequency of calcium-dependent depolarisation and actin (a muscle protein) polymerisation in a pattern that follows the Kuramoto model (a mathematical model that describes synchronous oscillators). This increases waves of peristalsis and growth in those directions. Furthermore, slime mould exhibits a form of memory. Experiments were carried out where slime mould was exposed to periodic noxious stimuli, in the form of colder and drier conditions. To cope with this, slime mould slowed its metabolic rate and locomotion. When the conditions ceased, the rate of locomotion returned to normal. However, when they stopped the noxious stimuli altogether, the slime mould continued to periodically slow down its locomotion in accordance with the former pattern of noxious stimuli for a period of time.

This is hugely relevant to the fundamentals of cognition in our own nervous systems.

What is beautiful about this is that the whole thing is determined by the action of calcium-dependent Kuramoto oscillation. This is hugely relevant to the fundamentals of cognition in our own nervous systems. Kuramoto oscillation accurately models the actions of our neurons and can mimic the effects of neurodegenerative diseases, like Parkinson’s Disease. Calcium ions are critical to our normal neuronal function and more recently have been considered to have a role in quantum consciousness. I know I said quantum mechanics was click-bait and merging that with neuroscience is the most basic thing possible – but oh well, it is pretty cool. 

In the 1999 book, The Feeling of What Happens, Portugese-American neuroscientist Antonio Demasio outlined his theory of levels of consciousness. In this, he described a bottom tier of cognition, known as the protoself. This is the most basic level of computation, consisting of neural patterns that regulate the minute-by-minute maintenance and homeostasis of the organism, rather than any conscious thought. This is exactly what our slime mould exhibits, to the point where the proponents of slime mould consciousness refer to it as “protoconscious”

What we can learn from this is that we do not need a massive coordinative centre, like the brain, to experience a level of cognition. Francis Crick and Christof Koch have described “neural correlates for consciousness” – lines of sensory information that come together to make up our experience of consciousness. This is the bottom up approach. It could be argued that slime mould demonstrates this as the Kuramoto model deals with synchronous oscillation across the organism. It is true that the number of inputs is nowhere near as vast as in animalia, but it does offer a snapshot into the mechanism through which our own cognition could work. 

We are not so different to those gross little blobs of mould – they offer a glimpse into the mechanisms through which we gain exactly what it is that defines us as human, our sense of self. If we base theories of consciousness on these living turds we will start off with a strong knowledge-base to grow our theory. For example, the tubulin structures that run throughout slime mould have been outlined as critical to their computation; these exist in large volumes in our neurons and particularly in our brains. Furthermore, quantum mechanics being a basis for consciousness is a theory that is becoming increasingly popular, but the link between calcium ions and oscillation modelling makes the argument even more compelling. In order to model and understand our consciousness, we should first be able to fully describe these basic mechanisms of cognition, and slime moulds could be a good place to start. From there it is a matter of scaling up the mechanism to account for the noise and complexity of human systems, with the ultimate aim of fully deriving the mechanism for our experience of consciousness.

This post was written by Harin Wijayathunga and edited by Ailie McWhinnie.

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