Could One Physics Theory Unlock the Mysteries of the Brain?

The ability of the phenomenon of criticality to explain the sudden emergence of new properties in complex systems has fascinated scientists in recent decades. When systems are balanced at their “critical point,” small changes in individual units can trigger outsized events, just as falling pebbles can start an avalanche. That abrupt shift in behavior describes the phase changes of water from ice to liquid to gas, but it’s also relevant to many other situations, from flocks of starlings on the wing to stock market crashes. In the 1990s, the physicist Per Bak and other scientists suggested that the brain might be operating near its own critical point. Ever since then, neuroscientists have been searching for evidence of fractal patterns and power laws at work in the brain’s networks of neurons. What was once a fringe theory has begun to attract more mainstream attention, with researchers now hunting for mechanisms capable of tuning brains toward criticality.

[rickstr]

I love the fact that brains are trying so hard to understand themselves

[jordanfarr]

Quanta is so good it hurts dude. This is that just-technical-enough layer for scientists to peer into each other's realms, and it is just shockingly beautiful.

[frankburkhard]

Made me think of the way half of the immune system is permanently busy suppressing the other half; like a detonating bomb frozen mid-air by its own regulatory systems, so as not to take out the whole organism trough sheer overkill. Looks like the two most massive adaptive complex systems exploiting the same principles. makes sense to me.

[mateusnicolinibezerra]

I can't comprehend how concepts like this don't make up the front page of YouTube or other websites. It's so fascinating

[Milkshakman]

One application of these ideas not mentioned is in better understanding human mental health. There are two papers that come to mind; "the entropic brain" and "REBUS and the Anarchic Brain", which attempt to use concepts like criticality to explain why psychedelic drugs, when used properly, can be effective treatments for a wide variety of mental health issues. To summarize, they posit that these compounds push brain dynamics to/beyond the critical point, which has the effect of inducing plasticity of beliefs; therefore allowing the possibility of reorganizing beliefs in ways conducive to increased wellbeing.

[Alasarey]

This theory very well summarizes the perceived notion experienced from living with epilepsy. So cool to believe that the epileptic phenomenon can be described as "Super-Critical Neurological Behavior".

[matematicke_morce]

This is eerily similar to the method I've been using for many years to overcome creative blocks. It goes like this: I come up with two very different ways that my project could go wrong, and then I alternate between fixing each of them, until I hit this critical point kind of like what's described in the video. Granted, the method isn't very time-efficient, but it's a good last resort when my other creative methods fail.

[primenumberbuster]

Woah I never thought yall would make a video on this topic. Thanks, this is one of my favourite ones.

[melaniepowell]

As a 53 year old who has suffered from four types of Epilepsy for 48 years I totally agree and think that this is a fantastic video and I can't wait for more to be revealed!

[jake_rogers_music]

My brain reaches the critical point about 1.2 million times a day- I’m an elementary school teacher

[johnathancorgan]

Why no mention of Stuart Kauffman? His early work with self-organized criticality and his time at the Santa Fe Institute in the 1980s and 90s were very important to this line of research.

[matteogirelli]

Yesterday prof. Parisi, noble laureate in physics 2021 for complex systems, was awarded a doctorate in physics ad honorem by the University of Padua (where galileo galilei worked). I believe it is worth mentioning as regards this topic.

[momamba]

I've always thought about the universal relationship between the micro and macro
That was so inspiring to hear that we're going to approach the system wholely-from all aspects
You know, months ago when I first did a research on slime molds and cosmic networks I unlearned the thought of "Biology is a branch of physics", I just observed nature doesn't have categories, and the physics, chemistry, biology are all the same things
Thank you Quanta for inspiring us♥️♥️

[meingutername]

Great video, thank you. Complex dynamic sytems with emergent properties and chaotic behaviour are known and researched since decades. But this was the first time I heard the concept of critical point mentioned in this context, really interesting. It would be fascinating to explore how behaviour and properties of systems at critical point are connected to emergence phenomena or the typival self-x properties of such systems.

[mahagonx]

In 2009 the paper "SORN: a self-organizing recurrent neural network" demonstrated that spike-timing-dependent plasticity (STDP) leads to criticality in a network (liquid state machine). Would be interesting to include it in the discussion.

[dgitpadre]

My one gripe with this video is that you went all the way to Indiana University, talked about fractals, and didn't interview Doug Hofstadter to speak on this! If you've read his books you wouldn't be shocked that there is something profound in self-organized criticality. That it evades being just completely mechanical computation, and has almost harmonious properties of symmetry and self-reference. Shilling for his work aside, this was super cool, and a little bit spooky.

[friedpicklezzz]

Bravo. This is why I have a YouTube premium account. The level of these short documentaries far exceed the mediocre content aired on the likes such as Discovery Channel.

It’s a complex topic explained really well. That’s not an easy task. I’m not in this field but could follow everything. Just the right level of detail and complexity.

[mohamedbensaid]

The sound in this video is so sharp to the ear

[alexanderx]

The thing that keeps it from exiting quasicriticality is neurotransmitter tolerance.
As an error correction mechanism, receptors availability and neurotransmitter production are inversely related. When there is high release the available sites get used up and the sensetivity of the system is moderated.
This is why drugs which take the brain beyond its typically acheivable criticality get less effective with additional dose and why a sustained concenration still moderates overtime even if it is not metabolized out. The potential of the system to deviate is used up. Note however that this will only be the case for drugs which do not change both systems or cause permanent changes to the system by affecting causal factors outside of the error correction mechanism and shift the equilibrium point.

[vladyslavkorenyak]

If you have somewhat independent critical systems that interact with each other in positive and negative ways, the homeostasis arises as an emergent propriety.