Your brain is constantly perched on the edge of chaos. And it’s not because you’re behind on 47 laptop updates or obsessing over that typo in an email you sent your boss.
No, because even at your most zen, your 86 billion brain cells strut along a tightrope between calm and catastrophe; serenity and disarray; order and disorder. At any moment, they could domino into disaster. But no need to panic.
This tricky brain stunt is actually a good thing.
It’s probably why you can juggle all your racing thoughts in the first place, and in fact, scientists even believe tracking this precarious state could one day lead to an exciting new generation of mental health therapies.
We’re part of the universe
You might’ve noticed your lungs look like trees.
It’s because both abide by a fractal sequence, where an object continuously breaks out into smaller versions of itself. Tree branches resemble mini tree trunks, twigs are like mini-mini tree trunks and so on. This methodical pattern adorns snowflakes, blood vessels, lightning bolts and even the most riveting star explosions. Our universe loves structure. It loves order.
However, as physicists often say, our universe is also headed straight toward disorder. Barring a few nuances, Murphy’s Law captures the gist: “Anything that can go wrong, will go wrong.”
But between these two extremes, the universe has a third, even more intriguing state. Systems that tiptoe between harmony and mayhem. Mountains, threatening to collapse in an avalanche. The stock market, verging on a massive crash. And for the last decade or so, more and more research has shown our brains take residence here, too.
By studying the minds of monkeys, turtles, fish and, of course, humans, scientists have delved into this perilous place. It’s known as the “edge of chaos,” or less dramatically, the “critical point.”
“You have a mixture of structure that comes from the order, but then you also have some sort of randomness, which leads to variety, that comes from the side that’s on the disorder,” explains John Beggs, a professor of physics from Indiana University.
While some scientists believe the brain works with inputs and outputs (sort of like a computer), others — including Beggs — suggest it experiences the world by floating fluidly around this “chaotic” point. Presumably, such flux helps brains fulfill very important brain duties. A research paper published last month in Physical Review Letters, for instance, states the critical point offers brains a “desirable trade-off between linearity, optimal for information storage, and nonlinearity, required for computation.”
And when brains deviate from this crucial point, Beggs says, “that is associated with lots of disorders.” This bit is precisely why decoding the brain’s edge-of-chaos-secrets could help us revolutionize mental health treatment.
Already, studying the so-called critical point has begun changing the way scientists approach psychiatry.
“Researchers have turned to criticality based tools to improve their understanding of common psychiatric conditions like depression, schizophrenia, anxiety, post-traumatic stress disorder,” writes Vincent Zimmern, author of a 2020 paper titled Why Brain Criticality Is Clinically Relevant: A Scoping Review.
But before we dive into that, here’s what your brain is up to right now at the border between order and disorder.
Say your brain wants to signal for you to do something, like open up Seamless, the food delivery app. It must pass information along a network of brain cells, or neurons, to get you to tap the little orange square on your phone.
Theoretically, there are three ways it can go about that.
It can send the “hello, open Seamless” signal to more than one neuron at a time. It can send it to less than one neuron at a time. Or, it can send it to something like one neuron at a time. (Try to think about neurons as divisible into parts because we’re approaching the brain from a more mathematical standpoint than a biological one.)
Let’s assume your brain goes with one. One neuron talks to two neurons, which talk to four, and so on, like a gossip train. Soon, all your neurons are on high alert about your Seamless quest, or as Beggs puts it, the network “blows up really quickly.”
This is called supercritical behavior, and it’s usually way too much stimulation. You’d be in overdrive. Your brain would be so overwhelmed it would start glitching. And in fact, supercriticality is thought to be associated with chronic seizures, or epilepsy.
OK, that’s a no-go. What about two? One neuron sends information to half a neuron, which sends it to a fourth…then to an eighth… and the signal pretty much “dies out,” Beggs says. This is called subcritical behavior, and wouldn’t effectively pass the Seamless message along.
Our final path is three. One neuron shares information with “about” one neuron, which shares information with another, and the signal easily goes from point A to point B. This is good. This is called critical behavior. To effectively get a message like the Seamless one across a network of neurons, our brains “prefer” path three. Path one and path two both pose solid hurdles for neuron information transfer, but path three makes something like a neuron assembly line that ultimately connects the mind to the external world.
But remember how the critical point is also called the edge of chaos? Yeah, there’s more.
Consider the stock market, which also stands at the critical point.
Always, some people want to sell and others want to buy. It’s an almost exactly balanced duality, which is why markets are usually pretty steady. But what if something catastrophic occurs, like a global pandemic? Or a war?
People would panic, and as most financial gurus would agree, they’d start to sell. That’d spur massive market fluctuations. Chaotic fluctuations. “Market crashes are sometimes orders of magnitude larger than the typically observed daily loss,” Beggs explains. Think of these “fluctuations” as a signature of edge-of-chaos systems.
By contrast, some things follow what’s called Gaussian distribution, aka a standard bell curve, which doesn’t lead to those fluctuations. Human height is a good example of something with Gaussian distribution. If we were to map the height of every person in the world, we’d rarely see anyone fall far from the average. No massive fluctuations.
Of these two options, brains seem to have the edge-of-chaos signature.
When a horror movie jump scare happens, for instance, your neurons might “panic,” like stock market investors, and fluctuate into supercritical land. “You can have a cascade of activity or a neuronal avalanche that could travel through the entire brain,” Beggs said.
Now, you might be thinking, why wouldn’t the brain prefer a calmer, Gaussian lifestyle? The edge-of-chaos world seems highly risky. Well, there are a wealth of benefits to teetering between order and disorder, too.
Edge-of-chaos systems have a super-duper-ultra-wide range within which to work, thanks to the whole fluctuation thing.
With stock markets, there’s the chance you hit the jackpot. And with brains, “you could have information passed from one part of the brain to the next … and perhaps even go through the entire brain,” Beggs said.
Realistically, that’s important for alerting neurons to remain vigilant in a frightening situation, or maybe creating new brain connections while learning languages. In other words, when done very carefully, the brain can tread into chaos to help us function in a very (very) complicated world.
If the brain followed a Gaussian distribution, by contrast, it’d sort of be restricted when communicating stuff. It couldn’t reach neurons far across the organ during frightening situations to be like “hey neurons, turn on high alert, something is going to happen.”
In a 2009 paper, Manfred Kitzbichler — a neuroscientist from Cambridge University and among the first to consider the brain as residing on the edge of chaos — said criticality “would allow us to switch quickly between mental states in order to respond to changing environmental conditions.”
Further, leaving the critical point and heading into subcritical land might be helpful for our brain when we want to be on autopilot. Though scientists still aren’t quite sure how this mechanism would work, Beggs says “one possibility is if something is extremely well learned and highly rehearsed, it gets transferred to some sort of stereotypical circuit that just repeats its pattern.”
I’m on board, now what?
Well, most of the time in physics, researchers aren’t trying to negate what we already know, or even come up with new angles. Rather, they’re refining questions that have already been answered. This way, we can keep finding increasingly precise solutions.
The same is true for edge-of-chaos studies.
Human brains are constantly bombarded with external stimuli like people talking, bustling street noise and even the warmth of holding a coffee cup. This means neurons turn on and off constantly. Because of such flux, it’s unrealistic for the brain to be at the ideal critical point all the time. Imagine trying to walk along a straight line but people keep jostling you around as you step forward. It’s kind of like that.
Therefore, a follow-up question might be: What does our brain do instead? How does it operate there?
In a paper published last year in Physical Review Letters, Beggs’ team might’ve found the answer.
After running neurological experiments on mice, they saw that if the animals’ brains couldn’t access the critical point, they optimized themselves by following what’s called the Widom line, or simply, the second best choice.
Beggs calls this phenomenon “quasi-criticality.”
Other researchers studying how the brain operates around the critical point, by contrast, have suggested non-quasi-criticality solutions. Some have suggested brains always work slightly below criticality and others believe they randomly move around the critical point.
But, rolling with the quasi-criticality principle, Beggs started considering whether the brains of people suffering from mental illness, such as depression, have trouble accessing that second-best path.
“We looked at about 600 patients, and we’ve been plotting their different critical points,” he said. “From the trends, you can notice the age of the patient, or the gender of the patient, based on where they lie near this region of quasi-criticality.”
Therefore, it’s likely that “aging causes you to go to one place, depression causes you to go to another and epilepsy to another. But, they all might be equally far away from the critical point.”
That is, more research is needed to really decode the brain’s edge-of-chaos. Nevertheless, Beggs believes these findings will eventually lead to innovative therapeutics.
For example, he says we know the brain kind of shuts down for a while after having a really bad seizure. During that period, it has ways of trying to bring itself back online, one of which is growing lots of new connections. But, remember the supercriticality conundrum where way too many neurons turn on high alert, then “blow up” the network really quickly?
“You’d think that’s a good thing to do, because it’s just saying, ‘Hook this thing up again, and we’ll get some activity,’ but when it grows those connections after a seizure, once it comes back online, it’s over connected. So, it’s actually more common to have a seizure the next time.”
However, if we can harness the critical point, maybe we can stimulate brain tissue somehow and prevent it from sensing it’s in its shutdown state in the first place. Instead, it’d think everything’s fine, and therefore not make all those new connections that could lead to a subsequent seizure.
“If you sort of tricked it into not forming new connections,” Beggs said, “It would be far less likely to have a seizure.”
Right now, Beggs and fellow researchers are still in the process of dissecting how all of this works. It’s going to be a long, yet rewarding, road ahead. And if you’ve read until here, first of all congratulations.
Second, if you walk away with only one message, I hope it’s this one: The next time you’re stressed out, if someone asks how you’re doing and you say, “I’m on the edge of chaos,” you’re not being dramatic at all.
You’re being scientifically accurate.