Astral Codex Ten

Gyorgy Buzsaki

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Gyorgy Buzsaki

Article

Gyorgy Buzsaki is a recurring person in the Astral Codex Ten archive, appearing 2 times across 2 issues between October 20, 2022 and November 08, 2022. The archive places it in contexts such as “I read Rhythms Of The Brain by Prof. Gyorgy Buzsaki”; “RotB author Gyorgy Buzsaki’s new book”. It most often appears alongside Alexander Buhl, Alpha, Andres.

Metadata

  • Category: People
  • Mention count: 2
  • Issue count: 2
  • First seen: October 20, 2022
  • Last seen: November 08, 2022

Appears In

Source Context

Recovered passages from the original issue text. When the raw archive preserved outbound links inside the source passage, they are listed directly under the quote.

Book Review: Rhythms Of The Brain
October 20, 2022 · Original source
I read Rhythms Of The Brain by Prof. Gyorgy Buzsaki to answer these questions. This is a tough book, probably more aimed at neuroscientists than laypeople, and I don’t claim to have gotten more than the most superficial understanding of it. But as far as I know it’s the only book on brain waves - and so our only option for solving the mystery. This review is my weak and confused attempt to transmit it, which I hope will encourage other people toward more successful efforts.
Inline links: Rhythms Of The Brain
You get concentric rings of oscillating on and off! I can’t stress enough how fake this model is. Buzsaki doesn’t use it; even his simplified examples are much more careful. But this was what helped me (a person who is not a neuroscientist but does play around with Conway’s Game of Life sometimes) get a basic intuition of why the brain might produce oscillations. Here are five of the most important differences between this fake model and a real brain: 1: The real brain has more sources of oscillations. For example, many are produced by inhibitory interneurons - neurons that, when turned “on”, turn other neurons off: A normal excitatory neuron is linked to an inhibitory neuron. Whenever the excitatory neuron fires, it makes the inhibitory neuron fire; whenever the inhibitor neuron fires, it turns off the excitatory neuron. Once the excitatory neuron is off, that turns off the inhibitory neuron, leaving the excitatory neuron free to fire again if the original stimulus is still there. 2: Also, sometimes individual neurons oscillate on their own. Whenever they get too depolarized, that opens ion channels that repolarize them again, and vice versa. If you take a neuron out of the brain and put it in a test tube, it might fire at some natural frequency not necessarily related to its frequency in the broader network of the brain; it contributes its own frequency, which other nearby cells speed up or slow down. 3: In the fake model, every neuron was connected to a few nearby neighbors. The real brain has a much more complicated graph. Neurons can connect to thousands of other neurons, and one out of every X connections goes somewhere far away on the other side of the brain, for the same reason a good transportation network has some local trains vs. some express trains - you can get from Point A to Point B fastest with a combination of fast direct long-range connections and slower short-range ones. 4: The real brain includes many different kinds of neurons, inhibitory neurons, connections between neurons, and types of tissues with different graph theoretic organizations. If the fake model is kind of like the Game of Life, the real model is kind of like a version of the Game of Life in some contorted multidimensional space with each cell following a different rule set. 5: Also there is actual sensory stimulation and cognition happening in lots of places at once, messing up the otherwise elegant wave pattern. So instead of one oscillation taking over the whole brain, you get lots of oscillations with different properties arising, competing against, and interfering with each other, producing complicated self-organizing patterns that arise and disappear from moment to moment Complex patterns arising and evolving in the Game of Life. What Are Brain Waves Like? In the real brain, with many areas and types of neurons and sources of stimulation, the many different oscillations settle into what Buzsaki calls a 1/n, scale-free, or pink noise pattern. Complex waves can be decomposed by Fourier analysis into sums of simpler regular waves: (source) If you measure “brain waves” with an EEG, you get some very complex summed total wave. When you break it down, you find that as frequency goes up, power goes down, according to a power law. In the study of sound, this pattern is called “pink noise”. (source) Pink noise is apparently omnipresent in natural systems for kind of mysterious reasons - see eg this Quanta article, which says pink noise “is found in all kinds of electrical noise, stock market activity, biological rhythms, and even pieces of music — and no one [knows] why.” Buzsaki is pretty excited about this, and suggests that human-produced music has a pink noise spectrum in order to complement the pink noise spectrum of the brain; other sources argue that literal pink noise (for example, from a fan) has healing properties compared to white noise or silence. Did you know: White noise was named because its wave spectrum resembles white light. Pink noise was named because its wave spectrum resembles pink light. Brown noise was named after Robert Brown, who helped discover it. This is one of my least favorite facts. Lots of scientists seem tempted to wax rhapsodic about the importance of pink noise; the exact reasons were one of the parts of the book I didn’t quite understand. For our purposes, it just matters that this is the overall wave spectrum of the brain. How is this spectrum formed? This was one of the questions the book didn’t resolve for me. Are there a few hundred neurons here oscillating at 1 hertz, a few thousand there oscillating at 1.1 hertz, and so on, until we have enumerated thousands of different neuronal populations with very slightly different rhythms, and when you add them together you get the nice smooth pink noise curve? And then after a second, they all spontaneously rearrange themselves and there are a different few thousand populations and rhythms, still on the aggregate summing to pink noise? Sometimes it seems like the book is pointing to a model like this. Other times it seems like there are approximately five different rhythms in the brain, each with a name like “hippocampal theta” or “visual alpha”, and each usually involving a whole brain macroregion (eg the visual cortex). I still haven’t figured out how to reconcile these two perspectives - maybe the major rhythms are broad categories, and there are lots of subrhythms within them? In any case, these 1/n rhythms form the “background noise” of the brain. They exist at all times, whether you’re thinking hard, or in a sensory deprivation tank, or asleep (although each of those states will change which rhythm predominates). When neuroscientists want to study how the brain reacts to something, they usually measure the brain, do the thing, and subtract the pink noise spectrum from the result - again, on the grounds that it’s “background noise” which is disguising the effect of whatever their interesting intervention was. Buzsaki questions this practice and presents evidence that the state of the “background noise” matters a lot - this is the “randomness” that explains why the same person will respond to the same intervention different ways at different times. For example, he presents evidence showing that if you give someone a near-threshold stimulus (for example, a flashing light just barely bright enough that someone can detect it 50% of the time), then whether they detect it or not will depend on whether it occurs at the peak or the trough of the brain waves in the relevant area. Are Brain Waves Useful? Brain waves are kind of unavoidable. Rhythms presents a thought experiment about trying to design a brain that doesn’t fall into any natural oscillatory patterns. It’s pretty hard! Even if brain waves were useless, we would probably have them just because they’re too much trouble to avoid. Still, evolution tends to make virtues out of necessity, and Buzsaki thinks brain waves matter a lot. Again without claiming to have fully understood this, here are four things that brain waves might do: Brain waves provide “synchrony”, allowing a smallest granular unit of time and essentially converting life into a turn-based game. Suppose that a snake bites your foot. You see the snake with your eyes, and also get a pain signal from your foot. The pain signal has to travel a long way, nerves have conduction delays, and so it reaches your brain well after the visual signal. But your brain needs to be able to combine the visual and pain signals into a single story (snake bit my foot). Brain waves separate experience into short granular “turns” so that the brain can attribute both stimuli to the same “turn” and connect them. It’s also possible I’m totally misunderstanding this part, sorry.
Inline links: https://substackcdn.com/image/fetch/$s_!vg24!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2Fbf360690-6ffc-41d9-8e6f-056bbe9e033e_1920x278.png, https://substackcdn.com/image/fetch/$s_!zvsa!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2F36224fdc-b706-4f38-8989-135b68f77668_360x240.gif, https://substackcdn.com/image/fetch/$s_!_l2P!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2F4b25b1e9-86ca-4d85-9d31-cc93472c5cf2_401x302.gif, source, https://substackcdn.com/image/fetch/$s_!JqB5!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2Fca9fb777-23a6-4cf4-b997-15e5861c5541_555x374.png, source, other sources argue, https://substackcdn.com/image/fetch/$s_!0bfI!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2F75286799-6c21-4dda-be19-12e4b2410dbc_389x369.png
(source) Pink noise is apparently omnipresent in natural systems for kind of mysterious reasons - see eg this Quanta article, which says pink noise “is found in all kinds of electrical noise, stock market activity, biological rhythms, and even pieces of music — and no one [knows] why.” Buzsaki is pretty excited about this, and suggests that human-produced music has a pink noise spectrum in order to complement the pink noise spectrum of the brain; other sources argue that literal pink noise (for example, from a fan) has healing properties compared to white noise or silence. Did you know: White noise was named because its wave spectrum resembles white light. Pink noise was named because its wave spectrum resembles pink light. Brown noise was named after Robert Brown, who helped discover it. This is one of my least favorite facts. Lots of scientists seem tempted to wax rhapsodic about the importance of pink noise; the exact reasons were one of the parts of the book I didn’t quite understand. For our purposes, it just matters that this is the overall wave spectrum of the brain. How is this spectrum formed? This was one of the questions the book didn’t resolve for me. Are there a few hundred neurons here oscillating at 1 hertz, a few thousand there oscillating at 1.1 hertz, and so on, until we have enumerated thousands of different neuronal populations with very slightly different rhythms, and when you add them together you get the nice smooth pink noise curve? And then after a second, they all spontaneously rearrange themselves and there are a different few thousand populations and rhythms, still on the aggregate summing to pink noise? Sometimes it seems like the book is pointing to a model like this. Other times it seems like there are approximately five different rhythms in the brain, each with a name like “hippocampal theta” or “visual alpha”, and each usually involving a whole brain macroregion (eg the visual cortex). I still haven’t figured out how to reconcile these two perspectives - maybe the major rhythms are broad categories, and there are lots of subrhythms within them? In any case, these 1/n rhythms form the “background noise” of the brain. They exist at all times, whether you’re thinking hard, or in a sensory deprivation tank, or asleep (although each of those states will change which rhythm predominates). When neuroscientists want to study how the brain reacts to something, they usually measure the brain, do the thing, and subtract the pink noise spectrum from the result - again, on the grounds that it’s “background noise” which is disguising the effect of whatever their interesting intervention was. Buzsaki questions this practice and presents evidence that the state of the “background noise” matters a lot - this is the “randomness” that explains why the same person will respond to the same intervention different ways at different times. For example, he presents evidence showing that if you give someone a near-threshold stimulus (for example, a flashing light just barely bright enough that someone can detect it 50% of the time), then whether they detect it or not will depend on whether it occurs at the peak or the trough of the brain waves in the relevant area. Are Brain Waves Useful? Brain waves are kind of unavoidable. Rhythms presents a thought experiment about trying to design a brain that doesn’t fall into any natural oscillatory patterns. It’s pretty hard! Even if brain waves were useless, we would probably have them just because they’re too much trouble to avoid. Still, evolution tends to make virtues out of necessity, and Buzsaki thinks brain waves matter a lot. Again without claiming to have fully understood this, here are four things that brain waves might do: Brain waves provide “synchrony”, allowing a smallest granular unit of time and essentially converting life into a turn-based game. Suppose that a snake bites your foot. You see the snake with your eyes, and also get a pain signal from your foot. The pain signal has to travel a long way, nerves have conduction delays, and so it reaches your brain well after the visual signal. But your brain needs to be able to combine the visual and pain signals into a single story (snake bit my foot). Brain waves separate experience into short granular “turns” so that the brain can attribute both stimuli to the same “turn” and connect them. It’s also possible I’m totally misunderstanding this part, sorry.
Inline links: source, other sources argue, https://substackcdn.com/image/fetch/$s_!0bfI!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2F75286799-6c21-4dda-be19-12e4b2410dbc_389x369.png
Highlights From The Comments On Brain Waves
November 08, 2022 · Original source
[RotB author Gyorgy Buzsaki’s new] book seems to get at the idea that the brain is a self-coherent system, which is stable in and of itself without needing to be "driven" by sensory events. Anyway the summary [here] can do a better job than me, for the lazy its all summarised from about 1:02
I would say that there's a significant proportion of the field that is, shall we say, "skeptical" of the Buzsaki-style view on oscillations. Everyone agrees that the oscillations exist, and that changes in the oscillations are often correlated with changes in brain state, but making *causal* statements about their impact has proven much more difficult. There are certainly some suggestive data in the hippocampus pointing towards the importance of things like theta-band power and sharp wave ripples, but even there you get inconvenient data points like the fact that bats have a completely normal, functioning hippocampus with no apparent theta band oscillations: https://www.sciencedirect.com/science/article/pii/S0092867418312297
Inline links: https://www.sciencedirect.com/science/article/pii/S0092867418312297
On Buzsaki’s Next Book: