Brain Inspired

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Ehud Ahissar runs the Ahissar Lab at the Weizmann Institute in Israel, where he studies the neuronal and behavioral mechanisms of perception. Ehud sees perception as a closed-loop process, in which organisms actively generate the sensory signals they interpret. Today, we discuss his development of an idea about how this kind of processing can account for our conscious experience. It's a type of dualism Ehud calls "perceptual dualism," different than the dualisms you may already know. I'll use his own words to summarize it here…

"The idea is that humans inevitably experience the world through two fundamentally different modes: digital brain–brain (BB) communication and analog brain–world (BW) interaction. In this view, the mind, and consciousness, emerge as social-like phenomena (in the philosophical sense), grounded in BB communication while constrained by BW interaction."

Take note of the term brain-brain, shortened as BB, and the term brain-world, shortened as BW, because throughout our discussion you'll often hear just BB and BW to refer to those two distinct domains.

So we discuss the ins and outs of his ideas, how came to them via studying active sensing in rodent whisker neurophysiology, how the brain implements this dualism via nested loops of neural circuitry that oppose and interlace with each other at multiple levels, and the idea that attractors, in the dynamical systems sense of attractor, may be the corresponding brain signatures of the digital phenomena that belong to the brain-brain mode of cognition.

Ahissar Lab

Related papers

Digital–Analog Perceptual Duality

Closed-loop perception: gaps between artificial intelligence and biology

0:00 - Intro
5:09 - A new kind of dualism
7:19 - Ehud's whiskers background
14:10 - Digital-analog perceptual dualism
26:08 - Digital communication between humans
32:26 - Attractors as the digital-analog interface
39:50 - Consciousness
50:11 - Dynamics and perceptual bottleneck
51:47 - Language, AI, and digital symbols
1:00:54 - Computation and brains (digital and analog)
1:06:43 - Improving AI with event based activation
1:11:10 - Dualism
1:17:26 - The hard problem of consciousness
1:21:26 - BB and BW interaction
1:24:55 - Tension between BB and BW
1:34:28 - Looking forward
1:37:37 - Srange loops

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The Transmitter is an online publication that aims to deliver useful information, insights and tools to build bridges across neuroscience and advance research. Visit thetransmitter.org to explore the latest neuroscience news and perspectives, written by journalists and scientists.

Read more about our partnership.

Check out this story:

From genes to dynamics: Examining brain cell types in action may reveal the logic of brain function

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To explore more neuroscience news and perspectives, visit thetransmitter.org.

Liset de la Prida is director of the Centro de Neurociencias Cajal in Madrid, Spain, where she runs the Laboratory of Neural Circuits. Today we discuss two main topics.

What drew me to invite Liset was her work on neural manifolds, which we've talked about a lot recently on this podcast. She studies how specific subtypes of neurons affect and control neural manifolds. More on that it in a second, because what drew her to study manifolds was her work on what are known as sharp wave ripples in the hippocampus. Sharp wave ripples are generally quick bursts of oscillatory activity as found in local field potential recordings that accompany little bursty sequences of action potentials fired off by sets of neurons. Those ripples have been associated with a quick replaying of some experience an organism has had, with the thinking that by replaying those sequences of neural activity associated with an event, it's helping to consolidate the memory for that event in the cortex. Like everything else, the story isn't so simple, and we talk about some of the findings that have added to the complexity of understanding what sharp wave ripples are doing, and the varieties of sharp wave ripples.

That varieties part is related to the second main thing we discuss, which is the varieties of neuron subtypes and their roles in shaping the manifolds we've discussed a lot recently. As a reminder, manifolds are dynamic structures along which populations of neural activity unfold over time, and they have proved to be one effective way of making sense of how large populations of neurons coordinate their activity to do useful things for our cognition. Liset is interested in the relation between sharp wave ripples and manifolds, and in how specific subtypes of neurons affect manifolds and cognition in general.

Neural Circuits Lab

@lmprida.bsky.social; @LMPrida

Book:

Brain, space and time: The neuroscience of how we navigate reality, memory, or the future

Related

From genes to dynamics: Examining brain cell types in action may reveal the logic of brain function

Cell-type-specific manifold analysis discloses independent geometric transformations in the hippocampal spatial code

From cell types to population dynamics: Making hippocampal manifolds physiologically interpretable

0:00 - Intro
5:29 - Hippocampus
9:31 - Sharp wave ripples
27:30 - Oscillations and epiphenomena
33:37 - Sharp wave ripples to manifolds
43:54 - Manifolds and single neuron types
49:45 - Hippocampus and granularity of cell types
59:23 - Explanation across levels
1:19:38 - Manifolds and higher cognition
1:29:46 - Brain Space and Time

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The Transmitter is an online publication that aims to deliver useful information, insights and tools to build bridges across neuroscience and advance research. Visit thetransmitter.org to explore the latest neuroscience news and perspectives, written by journalists and scientists.

Read more about our partnership.

Sign up for Brain Inspired email alerts to be notified every time a new Brain Inspired episode is released.

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Brains encode information in representations that perform computations to make predictions, right? No, no, no, and no. That's Romain Brette's response to those ill-conceived notions that neuroscience relies on to try to explain how cognition works. He uses more words to do that in his new book, The Brain, in Theory, which we discuss today. In the book Romain breaks down how many of the common metaphors we use don’t withstand scrutiny, and he offers alternative approaches more in line with what we know about how biological entities work. Along those lines, we discuss his ongoing work understanding the cognition of a single celled organism, the paramecium, and what his views might mean for artificial intelligence. This is a long episode, but there's a lot more to be explored in the book, so I recommend you read it. If you're a patreon supporter, I coaxed Romain back on for another 45 minutes to go deeper on his thoughts about how anticipation is the core of cognition, how predictive processing accounts like active inference miss the mark, and a few other topics.

Romain's website.

The Brain, in Theory.

0:00 - Intro
4:01 - The Brain, In Theory
7:10 - Influences
13:11 - Process metaphysics
18:39 - Observer vs system perspective
21:24 - Information in the brain?
22:56 - Why this book?
29:52 - Computations in the brain
52:14 - Behavior is not a computation
1:07:20 - Paramecium cognition
1:22:02 - How should neuroscientists proceed?
1:29:09 - Cognition as collective behavior of autonomous cells
1:36:47 - Constraints, causes, and laws
1:52:36 - Hopes for the book to influence the field
1:55:04 - Thoughts about AI
2:02:13 - Computation and goals
2:08:17 - Anticipation vs prediction

Support the show to get full episodes, full archive, and join the Discord community.

The Transmitter is an online publication that aims to deliver useful information, insights and tools to build bridges across neuroscience and advance research. Visit thetransmitter.org to explore the latest neuroscience news and perspectives, written by journalists and scientists.

Read more about our partnership.

Check out this story: Neural manifolds: Latest buzzword or pathway to understand the brain?

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To explore more neuroscience news and perspectives, visit thetransmitter.org.

Juan Gallego runs the Neocybernetics Lab at the Champalimaud Centre for the Unknown in Lisbon, Portugal, affiliated with the neuroscience of disease and neuroscience programs, and the centre for restorative neurotechnology.

Juan has worked a lot on neural manifolds - the mathematical objects neuroscience is using more and more to describe how big populations of neurons coordinate their activity to do useful things. In fact, he recently gave a short talk that he titled The Manifold Manifesto, because he was asked to be provocative. And he was provocative, suggesting that manifolds are real - as real as chairs and tables are, that they have causal power, and they might be a target of evolution. Of course he talked about his own and others work to support those claims. So today we discuss many of those themes, through the lens of his own and others work, and we talk about what keeps him up at night about the possible limits of using manifolds to connect brain activity with behavior and mental phenomena.

He's not just a manifold person, though. Juan is more broadly interested in motor control and how brains do it.

We also discuss his work in patients with spinal cord injuries, who don't have enough nerve connections to their muscles to actually move, but have enough nerve connections that some signal gets through. Juan and his colleagues can detect that little bit getting through, and use it to infer what behaviors the patients intend to do, and they can use that information to control actions in a computer simulation. The hope is that this will translate to controlling prosthetics to give spinal cord injury patients their mobility again.

Neocybernetics Lab.

@juangallego.bsky.social

Related papers

A neural manifold view of the brain.

A neural implementation model of feedback-based motor learning.

Conjoint specification of action by neocortex and striatum.

Integrating across behaviors and timescales to understand the neural control of movement.

Evolutionarily conserved neural dynamics across mice, monkeys, and humans.

Read the transcript.

0:00 - Intro
4:37 - Manifolds
14:30 - Strengths and weaknesses
24:32 - Conserved manifolds across animals and species
34:31 - Causality and manifolds
47:29 - Constraints and causes
51:05 - What to measure
58:55 - Complexity and manifolds
1:10:29 - Juan's background
1:14:08 - Prosthetics for spinal cord injuries
1:41:06 - Integrating across behaviors and timescales
1:46:56 - Conjoint specification of action by neocortex and striatum.

Support the show to get full episodes, full archive, and join the Discord community.

The Transmitter is an online publication that aims to deliver useful information, insights and tools to build bridges across neuroscience and advance research. Visit thetransmitter.org to explore the latest neuroscience news and perspectives, written by journalists and scientists.

Read more about our partnership.

Sign up for Brain Inspired email alerts to be notified every time a new Brain Inspired episode is released.

To explore more neuroscience news and perspectives, visit thetransmitter.org.

Tom Griffiths directs both the Computational Cognitive Science Lab and the Princeton Laboratory for Artificial Intelligence at Princeton University. He's been on brain inspired before to talk about his previous book Algorithms to Live By: The Computer Science of Human Decisions, which he co-wrote with Brian Christian. Today he's here to talk about his new book, The Laws of Thought: The Quest for a Mathematical Theory of the Mind. In this book, Tom explains how the three pillars of logic, neural networks, and probability theory complement each other to explain cognition, arguing we are on the doorstep to settling what mathematical principles - the so-called "laws of thought" - underly our cognition. So we discuss a little bit about a lot of things, including the concepts themselves, the people who have generated and worked on those concepts. I should also mentioned, Tom recorded a bunch of his interviews with people he writes about, and he's edited and polished those into a podcast called the Cognition Project, which I have enjoyed after reading the book, and I think you'd enjoy it either before or after you read the book.

Computational Cognitive Science Lab

Princeton Laboratory for Artificial Intelligence

Social: @cocosci_lab; @cocoscilab.bsky.social

Book:

The Laws of Thought: The Quest for a Mathematical Theory of the Mind.

Podcast: The Cognition Project

Read the transcript.

0:00 - Intro
3:20 - Tom's approach
7:19 - 3 pillars of the laws of thought
28:24 - Logic and formal systems strip away meaning
39:04 - Nature of thought
50:35 - Kahneman and Tversky
1:015:12 - Enabling constraints and inductive bias
1:12:51 - Hidden layers, probability, and hidden markov models
1:20:47 - Conscious vs nonconscious
1:23:43 - Feelings
1:31:26 - Personal