The Crucial Role of Chaos in Our Brains’ Extraordinary Functions

Think back through your day and consider all the amazing tasks your brain has aided you in accomplishing. From simple activities like brushing your teeth to complex tasks such as reading, your thoughts, feelings, and actions might appear to stem from a finely-honed machine.

Merely stating your name is a small marvel, with electrical signals zipping across a 1.3-kilogram lump of jelly. “You’re pulling off one of the most complex and exquisite acts of computation in the universe,” states Keith Hengen, a biologist at Washington University in St. Louis.

The precise mechanisms that facilitate this complexity have puzzled both philosophers and neuroscientists for centuries. However, new research suggests that the key may lie not in precision but rather in the brain’s inherent messiness.

A New Perspective: The Critical Brain Hypothesis

Researchers such as Hengen propose the “critical brain hypothesis.” This theory states that our brain exists near a tipping point between cohesion and chaos, which they refer to as the “critical zone” or more evocatively, the “edge of chaos.” Not unlike avalanches and forest fire spread, the brain functions in a state where small events lead to significant consequences.

Systems on the verge of criticality adhere to strict mathematical principles, and it appears these dynamics may similarly clarify our minds’ remarkable efficiency and adaptability. “Criticality provides a powerful framework for interpreting brain function and dysfunction,” adds Karim Jerbi, a neuroscientist at the University of Montreal.

This hypothesis might be pivotal in predicting the impacts of psychoactive drugs, improving diagnostic methods for conditions like Alzheimer’s, explaining variations in intelligence, and even delving into the mysterious nature of consciousness.

Exciting developments hint that certain meditative practices could help us shift our brain states, enhancing our mental agility.

Tracing the Roots of the Theory

The origins of the critical brain hypothesis can be traced to Danish physicist Per Bak, who outlined the rules governing critical systems in the 1980s and 90s. He demonstrated that the propagation of forest fires lies on a tipping point; veering too far in one direction leads to rapid devastation, while straying too far in the opposite direction causes fires to extinguish too quickly.

Bak revealed that forest fires could exhibit “scale-invariance,” indicating that fires of varying magnitudes were possible. The frequency of these events aligns with a “power law” that is contingent upon factors like the ecosystem’s climate and terrain.

By the early 2000s, neuroscientists began observing that the brain’s electrical activity exhibited similar patterns. Neurons interconnect in intricate synaptic networks, meaning that one neuron’s activation can trigger others to respond. “Activity accumulates much like an avalanche,” explains Jordan O’Byrne, a PhD student of Jerbi’s, who recently published a review of the growing evidence supporting the critical brain hypothesis.

To explore this concept, researchers John Beggs and Dietmar Plenz studied rat brain slices, measuring neuronal electrical activity as they spontaneously fired within a Petri dish.

They discovered that, on average, each active neuron triggered only one additional neuron to fire as a consequence—a figure indicative of the brain’s tipping point. If this ratio were enlarged, avalanches could spiral out of control; if reduced, activity would evaporate before gaining momentum. The observed brain slices displayed the very scale-invariance and power law distribution characteristic of other critical systems.

Advancing Findings on Brain Dynamics

Subsequent research has demonstrated evidence of criticality across various forms of neuronal behavior, including the synchronization of disparate brain regions. Signs of criticality have even been observed across numerous species, including zebrafish, cats, monkeys, and, naturally, humans.

Nonetheless, some earlier studies did not identify the characteristics of criticality, prompting skepticism and motivating scientists to refine their methodologies. Hengen notes, “Skeptical groups have driven the field deeper into criticality analysis.”

In collaboration with Woodrow Shew, Hengen investigated data from 320 prior experiments and determined that seemingly contradictory results could be reconciled through improved statistical tests of criticality. Their findings were published in Neuron, a prominent neuroscience journal, in June.

Factors such as network connectivity and neurotransmitter balance strongly influence an individual’s proximity to the critical point. “There’s a zone of healthy functioning around criticality,” asserts Shew.

This zone facilitates adaptive thinking, allowing the brain to be stable enough to interpret the world while dynamic enough to respond optimally to it. “It provides the brain latitude to modulate its level of criticality based on circumstances,” explains O’Byrne.

The Link to Intelligence and Creativity

The fact that the healthy brain operates near criticality may endow it with notable advantages. First is the enhanced capacity for information processing and transmission. The scale-invariance characteristic of critical systems allows signals to travel across both minor and substantial distances, enabling effective communication within and between various brain regions. This yields a significantly higher computational capability. “The brain can navigate the full solution space,” remarks Hengen.

Positioning itself between order and chaos may also aid the brain’s ability to adapt to new circumstances. “It permits the brain to be stable enough to comprehend the world while fluid enough to respond appropriately,” notes Jerbi. If this hypothesis holds, we might predict that minor variations in proximity to the critical point impact cognitive performance—an expectation validated by research conducted by Naoki Masuda and his team.

The researchers engaged 138 adults in tests measuring fluid intelligence, the capacity to apply reasoning and logic to unfamiliar problems. These assessments were then compared with fMRI scans measuring brain activity. Masuda and his colleagues found that individuals with higher intelligence scores tend to operate closer to the boundary between order and chaos than those with lower scores — exactly what would be anticipated if criticality enhances the brain’s processing and calculation abilities.

This heightened flexibility seen near the critical point was demonstrated in a study by Jaana Simola and her collaborators. Participants played a computer game requiring them to adapt swiftly to changing rules; those with brains closer to the critical point showcased better performance.

Jerbi postulates that this proximity may be particularly crucial for creativity, defined as the ability to navigate novel ideas while maintaining sufficient structure to render them meaningful. “Criticality may cultivate the optimal neural landscape for fostering this process, enabling the brain to transition seamlessly between divergent thought and focused reasoning,” he says.

However, significant deviations from the critical zone—whether toward order or chaos—can lead to severe cognitive dysfunction. “Criticality bestows the brain its distinct edge, but it also means that minor shifts — owing to stress, illness, or injury — can sometimes push it into detrimental states,” cautions Jerbi.

Alzheimer’s disease vividly illustrates this point, as research indicates that patients often experience substantial brain degradation prior to notable cognitive decline. This could signify a tipping point when the brain struggles to maintain critical status, leading to a drastic decrease in cognitive functionality. “At a certain threshold, removing enough nodes from a network can significantly reduce the network’s richness,” explains Vincent Zimmern, a PhD student investigating the clinical implications of criticality.

The Role of Sleep in Brain Function

Interest surrounding brain criticality has burgeoned among neuroscientists, with increasing enthusiasm about its implications. Hengen speculates whether sleep has evolved to restore the brain to its critical state. His analysis of rat behavior underscores the strong association between fatigue and criticality. “The most reliable predictor of whether an animal will remain awake or fall asleep is its proximity to criticality,” he asserts. The closer an individual approaches this tipping point, the more probable they are to remain awake, while the further they are from it, the more likely they are to succumb to sleep.

This suggests that prolonged cognitive exertion pushes the brain away from the critical point, and that sleep helps recalibrate it. Absent sufficient rest, the brain may descend into an impaired state, leading to the well-documented cognitive deficits caused by insomnia. Quality and quantity of sleep play a significant role in numerous automatic processes, including breath regulation, according to Hengen. These extensive repercussions imply that sleep serves to mitigate an underlying factor influencing brain processing — its proximity to criticality.

O’Byrne echoes this sentiment, suggesting that sleep’s central function may involve recalibrating brain connections to restore overall dynamics to criticality.

Stimulants like caffeine could induce temporary boosts in alertness by pushing the brain toward criticality, albeit at a cost. Jerbi’s colleague at the University of Montreal, Philipp Thölke, recently conducted laboratory studies where participants were instructed to sleep under controlled conditions. Each was given caffeine doses—equivalent to a dense espresso—before bed on one night while experiencing withdrawal on another.

The team recorded the participants’ brain activity with EEG and established that caffeine consistently nudged the brain closer to criticality during sleep. “It maintained a semi-alert state in the brain,” explains Jerbi, also a co-author of the study published earlier this year. “This not only disrupted sleep patterns but also hindered the brain’s restorative functions.”

Exploring the Mysteries of Consciousness

Insight into brain criticality has led to attempts to conceptualize the complex phenomenon of consciousness. While challenging to define, most neuroscientists agree that consciousness involves a subjective perspective, integrating perceptions or mental constructs that evoke specific emotional qualities.

One predominant hypothesis, “integrated information theory,” posits that this subjective viewpoint emerges from the manner in which the brain processes and integrates data. Intriguingly, mathematical models suggest that information integration peaks when the brain gravitates toward the critical point, potentially linking this state to awareness of one’s thoughts and self.

To empirically test this theory, various anesthetic effects on consciousness have been examined. For instance, drugs like xenon and propofol appear to abolish conscious experience entirely, while ketamine results in dissociation—cutting individuals off from external stimuli without erasing awareness. Users may still perceive vivid dreams and sensations of self when administered ketamine.

Research published last year harnessed data from patients under different anesthetics, with findings indicating that while ketamine users’ brains remained near the critical zone, those under xenon and propofol drifted away from this tipping point. “This suggests that brain criticality may be fundamental to consciousness, though more research is necessary for definitive claims,” concludes O’Byrne.

Adjusting Brain States: A Potential Path

Given criticality’s significance in cognitive function, one might ponder whether individuals can fine-tune their brain’s position within the critical zone. Would it be possible to slightly diverge from this state before sleep or align it closer for complex tasks and creativity bursts?

Hengen is actively investigating this premise. “Woody [Shew] and I are analyzing whether we can influence a brain’s proximity to criticality to improve learning outcomes,” he reveals, remaining somewhat elusive about specifics. However, he notes that findings from animal experiments show promising results.

Meditation offers another potential avenue for modulating brain states; however, the specific form of meditation is crucial. For example, Samatha meditation—focused concentration on a singular experience such as breath—may push the brain away from criticality. “This finding is intuitive since criticality allows maximum sensitivity and flexibility,” elucidates O’Byrne.

Conversely, Vipassana, or open-monitoring meditation, promotes unprejudiced awareness of all thoughts and sensations. “In this case, we would expect criticality to be heightened, making the subject highly receptive to their environment,” notes O’Byrne. A recent assessment from Annalisa Pascarella provides exciting support for this idea.

This study analyzed brain activity among twelve Buddhist monks during their engagement in both Samatha and Vipassana for six minutes each. Using a magnetoencephalography (MEG) headgear, the researchers measured neural activity and observed that focused Samatha meditation shifted the brain away from the critical point, while Vipassana practice moved it toward it, suggesting it is indeed possible to cultivate the brain’s position within criticality through practice.

While each monk logged over 2000 hours of meditative experience, future innovations may make it easier for anyone to foster such adaptability. Jerbi highlights the upcoming possibilities with devices like neurofeedback, which display real-time brain activity via portable EEGs. This feedback could accelerate individuals’ training in specific meditation techniques.

Meanwhile, let us embrace those occasional moments of delightful chaos in our thoughts, for they might signal that we are comfortably residing within the critical zone, reaping its many advantages.