Dileep George: Brain-Inspired AI | Lex Fridman Podcast #115 | Summary and Q&A

August 14, 2020
Lex Fridman Podcast
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Dileep George: Brain-Inspired AI | Lex Fridman Podcast #115


Leap George, a researcher at the intersection of neuroscience and artificial intelligence, discusses the importance of understanding the brain in order to build intelligent systems.

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Key Insights

  • 🧠 Understanding the brain is crucial for building intelligent systems that closely mimic human intelligence.
  • 💁 Feedback and lateral connections play significant roles in the brain's information processing, allowing for top-down controllability and integration of local and global information.
  • 🎑 Dynamic inference enables the model to incorporate context and make consistent interpretations of visual scenes.


the following is a conversation with the leap george a researcher at the intersection of neuroscience and artificial intelligence co-founder of vicarius with scott phoenix and formerly co-founder of numenta with jeff hawkins who's been on this podcast and donna dubinsky from his early work on hierarchical temporal memory to recursive cortical netwo... Read More

Questions & Answers

Q: Why is it important to understand the brain when building intelligent systems?

Understanding the brain is essential because it provides valuable insights into how intelligence can be engineered and surpassed current models in mathematics and computer science.

Q: How does the Blue Brain Project work in building a brain model?

The Blue Brain Project aims to build a brain model without fully understanding its workings, using detailed biological neurons and interconnecting them based on statistical connections observed in neuroscience experiments.

Q: What is the significance of lateral connections in the visual cortex?

Lateral connections in the visual cortex allow for coordination between different parts of the visual field, ensuring that transformations are coherent. They help in generating accurate interpretations of objects and their relationships within an image.

Q: How does dynamic inference work in the neural model?

Dynamic inference involves continuously updating and integrating local evidence with global context, allowing the model to make consistent interpretations. It helps reconcile conflicting local information and derive meaningful conclusions about the visual scene.


In this podcast episode, Lex Friedman interviews Theanne LeGeorge, a researcher at the intersection of neuroscience and artificial intelligence. They discuss the importance of understanding the brain in order to build it and the limitations of current brain-inspired AI. LeGeorge emphasizes the need for a computational framework to connect neuroscience insights and build functional models of the brain. They also delve into the concept of feedback connections and top-down controllability in the brain's visual cortex. LeGeorge explains the significance of the cortical microcircuits and their role in perception and cognition.

Questions & Answers

Q: Do we need to understand the brain in order to build it?

Yes, if we want to build the brain, we definitely need to understand how it works. Building a brain without understanding it, such as with the Blue Brain Project, will not likely lead to success. Without a thorough understanding, it would be challenging to debug and refine the model.

Q: What is the Blue Brain Project?

The Blue Brain Project aims to simulate the brain by incorporating the details of the brain's structure and connections based on neuroscience experiments. However, simply simulating neurons and their connections is not sufficient. Without a solid theoretical framework, it is difficult to understand the contribution of each neural component.

Q: How are neurons modeled in the Blue Brain Project?

The Blue Brain Project uses biophysical models of neurons, which involve simulating the effects of turning on and off various channels and receptors in the neuron. These detailed models can replicate the neural dynamics of a single neuron, but they do not provide a complete understanding of how the entire system functions.

Q: Do neuroscience experiments provide valuable insights into brain function?

Absolutely. Neuroscientists have conducted rigorous experiments to understand various aspects of the brain, including the dynamics of individual neurons and the connectivity between different brain regions. While these experiments do not directly translate into a functional brain model, they provide crucial hints and information from which computational frameworks can be built.

Q: How far are we in our understanding of the brain?

It is difficult to predict timelines accurately, but we have made significant progress in understanding different aspects of the brain. For example, we have gained insights into the dynamics of individual neurons and the collective communication between neurons. However, there is still much to discover, particularly regarding the emergence of intelligence and the intricate mechanisms underlying brain function.

Q: What are the useful aspects of the brain for building AI models?

The visual cortex and its feedback connections are particularly intriguing. Neuroscientists have studied the detailed circuitry and conducted experiments to understand how neurons respond to stimuli and communicate with each other. These insights have inspired computational models that can perform tasks such as object recognition and segmentation.

Q: How does feedback connectivity play a role in the visual cortex?

Feedback connections in the brain allow for top-down controllability and inference. They enable the brain to project expectations onto the world and manipulate visual knowledge in cognition-driven ways. These connections facilitate the process of building a model of the world, inferring meaning from sensory input, and simulating scenarios.

Q: What is the concept of top-down controllability?

Top-down controllability refers to the brain's ability to generate and manipulate its predictions and expectations about the world. It allows us to control our perception and imagine different outcomes or scenarios. Neural networks, such as the Recursive Cortical Network (RCN) model, can capture this controllability by factoring the world into separate entities, such as foreground and background, and modeling the relationships between them.

Q: How do cortical microcircuits contribute to vision?

Cortical microcircuits are the circuits within a level of the cortex that encode various concepts or variables. Each cortical column represents a concept, such as the presence or absence of an edge or object. These columns are interconnected and communicate through complicated layered neural structures. Additionally, the connections between cortical columns and the thalamus encode the relationships between concepts.

Q: Are concepts in the brain human-interpretable or more abstract?

Concepts in the brain do not necessarily need to be human-interpretable. They can be represented as binary variables, indicating the presence or absence of something. The interpretability of these concepts can be derived from their connections and relationships with other concepts. The primary focus is on their usefulness in the brain's computational framework.


Understanding the brain is crucial for building it, but current brain-inspired AI should be approached with caution as it can be over-hyped. Building functional models of the brain requires a computational framework that integrates neuroscience insights. Feedback connections play a significant role in the brain's visual cortex, enabling top-down controllability and inference. Cortical microcircuits encode concepts and their relationships within the brain. The brain's perception and cognition systems are interconnected, and perception should not be seen in isolation from cognition. Future research should combine insights from neuroscience and AI to continue unraveling the mysteries of the brain.

Summary & Key Takeaways

  • Leap George is a researcher at the intersection of neuroscience and artificial intelligence.

  • He emphasizes the need to understand the brain in order to build intelligent systems and discusses the limitations of current brain-inspired AI models.

  • Leap George highlights the role of feedback connections, lateral connections, and dynamic inference in the brain's functioning.

  • He also explores the potential applications of his research, such as cracking text-based captchas.

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