This strikes me as totally unsurprising. How could it be otherwise? It's basically saying that a brain normally operates in an interesting dynamical mode: not chaotic, and not very regular. Wow? If it were chaotic, we wouldn't have coherent or consistent behavior at any scale. If overly regular, we'd be incredibly dull and unable to respond to the environment.
You could do this with a computer. If your signals coming from the computer are either too regular or too unexpected, then it's probably broken. This sort of thing might be useful diagnostically, but doesn't really provide us with greater understanding...
Complex Systems guy: we just showed a system operates in a critical state scale-free phase transition and its key statistics have a power law distribution!
Everyone: okay, so?
CS guy: I dunno? That's what our discipline does. It tells you things are in critical states with power laws. So now you know that...
The social politics that came out were most interesting to me. The person with a smaller contribution to the project taking a lion's share of credit. The lead, a soft coward who has been conditioned to let her take credit. The history of that tribe of people doing this sort of self promotion.
Indeed it has long been known that the awake human brain operates near a critical point. Unfortunately, their significance statement is very generic and doesn't really summarise their main contributions.
The abstract has more information, describing how this paper adds to the picture a mathematical determination of that critical point, and the insight that low-frequency oscillations play a key role when switching consciousness states.
The level of the experiments is quite high, also they use primates (humans and macaques), some of them epileptic, and they administer psychedelics. All this sets the paper apart from lower-tier work.
It doesn't strike me as a real ground-breaking paper, but still an important contribution to the field. And the methods are impressive.
I didn't read the whole thing, but I did find parts of it surprising.
Some things that jumped out at me:
> during conscious states, the electrodynamics of the cortex are poised near a critical point or phase transition and that this near-critical behavior supports the vast flow of information through cortical networks during conscious states
But we've had a lot of success building artificial systems that support a "vast flow of information" which I would expect are mostly nowhere near such a boundary. Stuff moves around within a periodic structure, and moving more info has corresponded to moving more information per period. Why would we not expect a pile of neurons with a ginormous number of connections to be able to move a lot of information even through largely periodic behavior?
> we found that the Lempel–Ziv complexity of the model’s simulated electrodynamics (with noise inputs) was maximal when the deterministic component of its dynamics were poised near this critical onset of chaos
I guess if the measure of "information richness" is based in compressibility of electrical activity ... is it surprising that it isn't higher in the chaotic phase? Why wouldn't one expect the chaotic system to produce as much or more random output?
> Why wouldn't one expect the chaotic system to produce as much or more random output?
Because neurons as systems don't like random input. Noisy random input doesn't make (most) neurons fire. Rather the opposite, actually.
Neurons aren't (usually) simple threshold comparators of a single input; they're arbitrarily-complex gate-like recognizers, that fire in response to detecting signals in their combined inputs, or even upon matching temporal firing patterns within the signals of their combined inputs.
In that sense, if you tune every component in the system to produce more noise (chaos), you decrease the signal-to-noise ratio, and so the components that react to "important recognizable changes in the signal" within that noise have a harder time recognizing the thing they're looking for, and so they recognize it less, and so switch less.
---
By trite analogy: suppose you're a security guard. Your job is to recognize+report "real crimes in progress", while not reporting "false alarms." (Pretend that the police charge for false dispatches in your town, so your boss wants to optimize shrinkage vs. call budget.)
Also, your boss has decided to "keep you on your toes" by introducing "noise" into your computerized security system. Sometimes it'll show a burglary in progress when there isn't one. Sometimes it'll show that everything's fine, when actually the boss has secretly sent in a white-hat burglar of his own.
How willing to believe the security cameras should you be, to optimize your output signal to downstream demand?
As it turns out, you should probably try to figure out the false-positive vs. false-negative rate you're seeing reported by the downstream, and then calibrate your confidence up/down until you're making a balanced number of Type 1 vs. Type 2 errors. That level of confidence is the "critical point" — where the noise in the system is equally likely to help your detection (by "correcting" a false negative/positive, turning it into a true positive/negative) as it is to harm.
Moving away from that critical point, in either direction, makes your output less useful as a downstream signal.
>I guess if the measure of "information richness" is based in compressibility of electrical activity ... is it surprising that it isn't higher in the chaotic phase? Why wouldn't one expect the chaotic system to produce as much or more random output?
Chaos can be highly regular. For example, the limiting case of the logistic map, x -> 4x - 4x^2, is chaotic, but also has an exact solution x[n] = sin^2(arcsin(sqrt(x[0])) * 2^n). It's not hard to see why this still obeys the usual properties of Lyapunov doubling etc, but a simple double exponential doesn't seem like the sort of thing that leads to consciousness! From an information-theoretic point of view, the nth bit of x[0] becomes relevant at roughly step n, which means there is a steady "trickle" of information into the system instead of the more complicated dynamics we expect of a "computational" system -- in fact, if we consider the binary expansion of (arcsin(sqrt(x[0]))/pi) we find that only a finite number of bits have an effect on the system's measurable properties at any time, and the effect is rather like scrolling steadily along an infinite tape of random bits.
This is not supported by the literature as far as I'm aware, do you have a source? Propofol, the most common adult surgical anesthetic, decreases neuronal activity via the mechanism of making it harder for action potentials to fire [0], and has a litany of effects few of which are excitatory , and generally correlated to decreasing cortical activity [1].
And ketamine, the most common pediatric and veterinary anesthetic, has a complex mechanism of action acting on GABA, NMDA, and other receptor systems, often with generally inhibitory characteristics [2] and with definite decrease in brain activity in animal models [3].
A captured signal may represent a pathway for intervention, a cause, or a margin to address.
Imagine if we found that schizophrenia or other potentially debilitating mental health condition were 99.9999% correlated with this signal being weak or strong. That would be telling. If only for diagnosis, and possibly as a cause.
It's interesting that we can measure, quantiatively, what the dynamical operating mode of a system is. It's interesting, to me anyway, because it's a high-level characteristic that describes most (all?) information processing systems.
>If overly regular, we'd be incredibly dull and unable to respond to the environment.
What do you mean by this? Are computers regular? What about a computer programmed to respond to its environment? What do you even mean "respond to environment"? Why does it operate in this mode when awake but not when asleep?
Please, since this research is so obvious to you, I would love to hear your insights on consciousness. They are far beyond mine.
I had the same reaction. I wouldn’t be surprised if you could even formalize it and say that all information processing takes place on this edge between stability and chaos. That’s where all interesting/useful Turing machines live, for example.
Im fairly uneducated in CS, but this fascinates me, could you expand more? I can see why the brain's randomly firing neurons leads to novel thought and exploratory behavior but other than generating random numbers for various purposes, what good is chaos? What turing machines for example? Thanks
It's not that the interesting Turing machines are chaotic, but they are close to the boundary, in the sense that they have interesting dynamical behaviour. The reason why it's so hard to do static analysis of computer programs (for example, an automated detection of memory vulnerabilities in C programs) is pretty much this near-chaotic dynamic behaviour that doesn't easily yield to static analysis.
One example that doesn’t require any CS to appreciate is Rule 110[1], arguably the simplest Turing complete system. It clearly shows this pattern graphically. Wikipedia describes it this way:
“Rule 110, like the Game of Life, exhibits what Wolfram calls "Class 4 behavior", which is neither completely stable nor completely chaotic. Localized structures appear and interact in complex ways.”
Pretty cool. I am surprised that low frequency dynamics are so strongly associated with reports of aware conciousnes states given that the high frequency 40 Hz activity of cortico-thalamo-cortical loops are necessary (if not sufficient) for consciousness as well. I'd put my money on the low frequency dynamics being a downstream effect from the cessation of the ~40 Hz cortico-thalamo-cortical loops under anesthesia. I'd also like it if they had included a gas anesthetic along with the receptor mediated anesthetics.
This appears to be an indication of a new phenomenon correlated to criticality in cortical electrodynamics, that also correlates to consciousness as we understand it.
It looks to me is a huge step, because even the result is so far empirical, the first step to understand anything is being able to measure it.
It's a weird feeling to realize how we're all just hardware, and it might be possible to wake up someone who's "brain dead"/vegetative by LSD (the paper mentions how psychedelics affect this cortical electrodynamics, and as this old article[1] mentions the LSD).
Imagine someone flipping a switch (in the future where tech to control the electrodynamics exists) and you're awake and aware of your surroundings again.
> “The first report of a zolpidem awakening came from South Africa, in 1999. A patient named Louis Viljoen, who, three years before, was declared vegetative after he was hit by a truck, had taken to clawing at his mattress during the night. Thinking he was suffering from insomnia, his family doctor suggested zolpidem to help him sleep. But 20 minutes after his mother ground the tablet up and fed it to him through a straw, Viljoen began to stir. His eyes, which normally wandered the room, vacant and unfocused, flickered with the light of consciousness. And then he began to talk (his first words were “Hello, Mummy”), and move (he could control his limbs and facial muscles). A few hours later he became unresponsive. But the next day, and for many days after that, zolpidem revived him, a few hours at a time” - https://www.nytimes.com/2011/12/04/magazine/can-ambien-wake-...
> The idea of using LSD as a treatment has floated around the Internet for decades. There are rumors — totally unconfirmed — that an astronomical dose of LSD — "a quarter of a vial," or 25 hits — woke up an unresponsive dude and, after a few days, he was able to speak. It's entirely possible those stories are true.
So, consciousness is like a big casino in which the brain builds a bets for different theories, and this chaos measured come from all the dice throwing.
It's hard to describe features of chaos / nonlinear dynamics simply.
There are features of chaotic systems that undergo phase changes from one type of behavior to another. Think a signal on one side of the transition to look like a pure sine wave and on the other side of the transition to look like purely random white noise.
What these guys are reporting is that they found a parameter, a signal they can measure in brains that seems to correlate with consciousness. When the signal is right up near the edge of this kind of chaotic phase transition, the subject is conscious, when nowhere near the phase transition, you aren't. So they have a way to sort of measure and quantify consciousness and perhaps even control it a little by measuring and doing things to manipulate this signal.
It might be sort of like an OPEN sign in a store, just a signal that happens to reflect consciousness, or this brain wave behavior might be a fundamental part of consciousness and higher thinking. It all seems quite interesting.
Projecting guesses out for this is that chaotic dynamics are a fundamental part of how our brains, especially at the highest levels work. One would guess given this evidence and other things that one of the things that makes consciousness possible is a complex system kept balanced at a knife edge of a certain kind of chaotic phase transition. It's also the kind of thing that can open a backdoor for free will in a deterministic universe, your brain in this chaotic state might behave deterministically but the actual state would never be knowable with enough precision to predict the outcome of inputs for any amount of time (butterfly effect).
> it's also the kind of thing that can open a backdoor for free will in a deterministic universe, your brain in this chaotic state might behave deterministically but the actual state would never be knowable with enough precision to predict the outcome of inputs for any amount of time
Hmm, what about predictability conflicts with the idea of free will? Just because my actions are predictable doesn't mean they aren't a reflection of my will. It seems to me that the opposite is true, there is no coherent "you" if your actions aren't based on a consistent set of rules since that implies how you behave ultimately has no connection to who you are. To escape determinism means to become literally insane.
For me personally, when I use the term "free will", I mean something stronger than "deterministic, but not provably so". That's more of a "free will of the gaps" - claiming that free will is hiding somewhere in the holes in our knowledge.
Whatever people mean by free will, this feeling like we're driving our bodies and minds around usually, there's no mechanism by which it could exist.
Either the things in our brains follow deterministic patterns or they're random. Neither one of those gives me room to decide to get a glass of orange juice. In fact, any desire I have at all for an orange is dependent on that type of plant having emerged billions of years ago. I can imagine a fruit that doesn't exist, but I can't desire it and I can't buy it at the store. I had no say in any part of that causal chain whatsoever.
> It's also the kind of thing that can open a backdoor for free will in a deterministic universe, your brain in this chaotic state might behave deterministically but the actual state would never be knowable with enough precision to predict the outcome of inputs for any amount of time (butterfly effect).
I think all it would mean is that the human brain is non-deterministic.
That’s different from free will though which is really an untestable, philosophical idea rather than a testable scientific hypothesis.
In any event, a random chaos state can be both non-deterministic and not intentional, or what many would call “free will”.
I always find it interesting drawing the determinism line on chaotic systems.
For example, is a chaotic system that depends on initial conditions so precise that having adequate measurement to predict the outcome would violate the uncertainty principle still deterministic?
"chaotic systems" aren't just... unpredictable things that we find laying around and say "yeah we'll call that chaotic because it looks like my kid's bedroom". they've got to satisfy that description.
I'm asking if there's a proof for determinism itself. I was under the impression that we've only ever been inferring consistency is a property of reality.
If you can QED me to a conclusion that yes, in fact, the sun will rise in the morning, I would genuinely find that useful.
If the underlying physics is deterministic, then a chaotic system (e.g. the Three Body Problem) is just a collection of deterministic parts interacting with each other, and is therefore itself deterministic. The overwhelming complexity and unpredictability we observe is just a commentary on our own ignorance and limitation as humans. There was never room for any non-deterministic thing to magic itself into the system at some point as the complexity and unpredictability of the system got bigger and bigger.
I appreciate the good faith engagement (cue side glare sigstoat), and I'm in agreement with everything but the use of "never" in the your closing sentence.
> There was never room for any non-deterministic thing to magic itself into the system
Depending what you mean by "into the system," existence itself is a glaring counterexample.
How did any of it get here in the first place?
Was there an uncaused cause?
Is entropy reversible?
Until we can explain-away these types of questions, it'd be prudent to remain noncommittal on the topic. The type of determinism that sigstoats expect might not even make sense in other regions or eras of reality. Things get profoundly hazy past Planck Era.
I wonder if it's possible to prove that you can't end up with a non-deterministic system if that system is constituted only by deterministic parts? I get the sense that such a proof is possible, but I am not sure. We can trivially prove it for deterministic systems that we can model mathematically, but what about a generic proof for those systems that are beyond our modelling capabilities?
Regarding existence itself, I agree that determinism is not an exhaustive set of possibilities (if it was, it would imply an infinite chain of causes, which presents its own problems). I just challenge the idea that one can possibly get a non-deterministic system if we assume that we're working with purely deterministic components/rules.
I've been thinking about it like we're located in some pocket of reality whose local conditions generate the nature we know and love, but outside of which might be unrecognizable.
Whatever the Big Bang event was, I'm assuming it was a result of some exterior nature.
What I worry about is whether or not its even possible to connect the dots between the two.
Gödel's second theorem may just straight up make this whole exercise pointless.
Just imagining that outcome gives me the urge to primal scream.
All I know for certain is I've got a lot of questions.
> I'm asking if there's a proof for determinism itself.
sounds like you tried to take a flying leap away from the mathematically sound, and pedestrian statement of darawk into philosophy. you should warn people about that, so that people know not to bother.
> If you can QED me to a conclusion that yes, in fact, the sun will rise in the morning, I would genuinely find that useful.
if "gravity" isn't enough of an answer for you, then nothing can ever be.
If the human mind is deterministic there's no free will. If it isn't there might be. That makes free will half of a scientific question - science can only rule it out.
Oddly, nondeterministic systems tend to be statistically more predictable than certain classes of deterministic systems (to wit: a chaotic system is a type of deterministic system). So possibly the opposite is true, you need the human mind to be (mostly) deterministic for there to be free will.
I personally don't think that any macromolecular physical system can be entirely nondeterministic. We just don't understand how to make predictions for the system yet, but being beyond our understanding doesn't make it nondeterministic.
> It's also the kind of thing that can open a backdoor for free will in a deterministic universe
It really doesn't, because free will implies control over one's choices. Randomness, non-determinism, etc. doesn't provide that, and I bet you can't describe a way in which it could.
"Think a signal on one side of the transition to look like a pure sine wave and on the other side of the transition to look like purely random white noise."
This reminds me of something Rupert Sheldrake says is possible - that consciousness is 'off-site', that the body is more of a radio receptor.
There is no magic, nor room for it for any person that believes in the scientific method. There are a sufficient number of real mysteries and wonders not to waste time with pseudoscience. The brain is not a consciousness antennae, and there are no good reasons to think so.
Consciousness is an emergent phenomenon entirely dependent on and contained within the brain.
brain-as-a-radio-antenna is a common trope amongst those who would believe that meatspace isn't capable of generating consciousness alone (always looking for some sort of elan vital, to equate with another pursuit for the magic stuff of life).
From a purposely scientific perspective, we have to begin with the working assumption that materialism is true, until such point that it is conclusively proven false.
There is no evidence that the brain works in any way like an antenna, at least insofar as any electromagnetic waves or other such messaging systems supported by the physics of our current world as we know it.
Thus, the brain-as-antenna thinking necessarily pre-supposes an other-worldly explanation; it assumes what it's trying to prove.
Even if it were true (HIGHLY unlikely), we can't begin with that as the starting point in our search for understanding it. Otherwise, our brains are incredibly adept at shaping our thoughts and concepts to fit those prescribed notions of animacy and otherworldliness.
It's no wonder that many pseudoscientific principles BEGIN with the presupposition that you have to be willing to believe in order for the effect to become apparent.
We can actually show that consciousness persists even when surrounded by shielding that would prevent the passage of any known particle or radiation except neutrinos from affecting whatever is inside.
If you shut off all outside signals, the brain works just fine, there's no effect at all. (Except maybe the stress of whatever situation you're in that landed you in a super shielded bunker. )
Except materialism has been proven false for the past 100 years thanks to quantum mechanics. There is mountains of evidence against it and none for it.
Quantum mechanics follows from physicalism by demonstrating that the physical nature of reality is incredibly complex and counterintuitive, particularly at quantum scales.
But that in no way implies that quantum mechanics leads to non-materialism or opens the door for materialism to be false. It simply becomes subsumed into materialism itself:
materialism requires that all phenomena be ultimately explainable via physical explanations, and those explanations must account for quantum-mechanical phenomena.
At some point, through mathematics or a sufficient resolution of simulation, we will be able to run software that achieves consciousness. Through rigorous proof, the first method will provide the basis for falsifiable conjecture and exploration of the phenomena of consciousness and subjective experience. The second path will require laborious, tedious, and methodical experimentation with the model to tease out the underlying math.
Consciousness exists. It ceases to exist when the brain is damaged or killed. We can predictably modify conscious systems with drugs and experiences. Particular types of injury and illness sometimes result in predictable consequences, letting us know things such as that the hippocampus is critical to memory, and that whatever hierarchy of semantic meaning is stored in the brain, neurons in the hippocampus represent ontological peaks in the mental landscape of constructed meaning.
With a sufficiently high resolution brain interface, you could record, replay, simulate, and share experiences between consciousnesses. If the mind is an emergent phenomena brought about within the confines of the skull, shared experience will be possible, up to the point that your subjective experience of being another person will be complete for the duration of the replay. If there's some outside factor playing a role in consciousness, it will be missing and likely prevent attempts at recording experience.
I'm interpreting it as there is a point in the meatspace of your brain that is like a sailboat on a stormy sea. The Water is one level, the air is another, and your consciousness is the sailboat that glides around where the two meet.
Using the radio metaphor, I think I could edit the radio so that the signal would be heard differently. Just turning up the volume is a sort of alteration of consciousness, as would be increasing/decreasing the bass/treble.
These are alterations to the way the sound is experienced, but do not affect the signal itself.
Maybe taking drugs would be akin to running the received signal through some sort of special effects board? Ie a different/unusual type of alteration to the signal.
+1...but my reaction to folks who worry much about free will in a deterministic universe, "butterfly effect quasi-free will", etc. is that they really should have gotten outside to play more when they were kids.
The 1992 book, Complexity: The Emerging Science at the Edge of Order and Chaos, arguably remains the classic introduction to complexity theory. And it doesn't require any maths.
So to put things simply, this comes from a view of a neuron (or network of neurons) as a dynamical system with various states. These states are constantly in flux and we can describe the states as patterns that are seen from plotting the pieces of the instantaneous state of the system in question. These patterns will repeat and change over time based on inputs and such, hence the term "phase change"
At least that's my current understanding of the matter, coming from the mouth of an undergrad late in a biochem degree with a focus on neuro
What does "a critical point or phase transition [of the] electrodynamics of the cortex" mean? Electricity doesn't have "phases" AFAIK (well there's two/three-phase power but I don't think that's what they're talking about).
Interesting, though the only example I see listed in that article that's not a change in the physical properties of matter is the ferromagnetic<=>paramagnetic phases.
Lots of the list are changes of physical properties of matter (e.g. breaking of physics symmetries in the cooling universe)... that are not conventional matter phase transitions between e.g. liquid and gas.
One that isn’t a matter it’s convection currents in a closed vessel between two plates of different temperatures.
At low differentials there’s no convection just conduction, as you raise the temperature difference you get a stable single circulation loop which is well behaved, continue further and you get a tempest of circulations coming and going in an entirely unpredictable manner.
There are distinct phase transitions between each of these states.
Another one is a forced double pendulum. With just a little periodic force they swing gently back and forth, with a lot they do constant crazy unpredictable loops around each other.
And if you're still interested, there's a more in-depth explanation with mathematical formulas and all. Even if I understood only 10-20% of what Ken Wilson was talking about, he gives a lucid motivation for why critical points are important and why they can be found in practice using renormalization groups, and not computer simulations:
Its a transition between distinct operational phases of a dynamic system, iirc these can be described with a (my terminology may be a bit off here) topological phase diagram
I find that it's disingenuous to propose attributes of consciousness when consciousness hasn't even properly been defined. There is not a shred of evidence that something like our concept of consciousness even exists.
Consciousness here means being in a conscious state, i.e. not sleeping, not fainted, not in an altered psychedelic state. It is clearly defined. Regrettably the word consciousness also refers to the "hard-problem of consciousness" thing.
And incidentially the field has a huge problem with pseudoscience, with studies that are not replicable, lying with statistics, theories which aren't falsifiable...
The problem with consciousness is that the only evidence it exists is that individuals claim to experience it, without even really defining what it is they experience. This "evidence" has a much simpler explanation than the existence of an almost-magical consciousness.
It's not that there can't be something like consciousness, but there is currently nothing to indicate this.
Materialism died out over a 100 years ago and has been repeatedly proven through hundreds of experiments from labs throughout the world to be total junk science.
Why do people feel the need to continuously push this fake science?
"This book deals with epiphenomenalism, which has to do with consciousness as a mere accessory of physiological processes whose presence or absence... makes no difference... whatever are you doing?"
You could do this with a computer. If your signals coming from the computer are either too regular or too unexpected, then it's probably broken. This sort of thing might be useful diagnostically, but doesn't really provide us with greater understanding...