Jeff Hawkins: Founder of the Redwood Center for Theoretical Neuroscience and Numenta, author of On Intelligence, working to reverse-engineer the neocortex and build brain-inspired AI.
What this episode covers
Jeff Hawkins lays out his lifelong mission to understand how the human neocortex produces intelligence, arguing that studying the brain is the fastest route to building intelligent machines. He traces his work from hierarchical temporal memory to his recent Thousand Brains Theory, which proposes the cortex stores everything in reference frames and that thousands of cortical columns each build complete models that vote to reach consensus. He critiques deep learning's point-neuron model as too simplistic, explaining how real neurons act as time-based predictive engines using sparse representations. The conversation ranges across continuous learning, consciousness, existential AI risk, and why he believes intelligent machines should not be made human-like or emotional. Hawkins ends with a vision of intelligent machines preserving humanity's knowledge as our true legacy.
Recommended on this episode
Why Red Doesn't Sound Like a Bell
Kevin O'Regan
“The best treatise I've read about this is by a guy named O'Regan, he wrote a book called why red doesn't sound like a bell”— guest
The guest's own work
On Intelligence
Jeff Hawkins
“in this 2004 book titled on intelligence and in the research before and after he and his team have worked to reverse-engineer the neocortex”— Lex Fridman
On Intelligence
Jeff Hawkins
“the hierarchical temporal memory theory which you first proposed on intelligence and went through a few different generations”— Lex Fridman
Also referenced (named, not recommended)
Anki
“there's an app called Anki that helps you remember different concepts and they talk about like a memory palace”— Lex Fridman
The Denial of Death
Ernest Becker
“do you know the denial of death by Becker... there's a thought that death is our whole conception of our world model kind of assumes immortality”— Lex Fridman
Big reveals from this episode
- Hawkins's core Thousand Brains claim: there is no single model of an object; thousands of cortical columns each build complete models that vote to reach consensus.
- The central insight that the neocortex stores everything in reference frames anchored to objects, like CAD coordinate systems, throughout the entire cortex.
- Theory that the cortex repurposed ancient grid cells and place cells used for spatial navigation to build maps of abstract concepts.
- Argument that artificial 'point neurons' barely model real neurons, which use thousands of synapses and dendritic spikes as predictive engines.
- Claim that the brain uses sparse population codes (about 2% active) which give robustness and resistance to adversarial examples.
- Assertion that backpropagation cannot happen in real brains; learning is pure Hebbian synaptogenesis on dendritic segments.
- Position that intelligence is just the neocortex and that we should deliberately not build AI with human emotions, drives, or desire to reproduce.
- Hawkins frames humanity's true legacy as knowledge, to be preserved beyond us through intelligent machines.
Worth remembering
- The neocortex occupies about 70 to 75 percent of the volume of the human brain and exists only in mammals.
- The neocortex is about 2.5 millimeters thick, roughly the size of a dinner napkin, and looks remarkably uniform everywhere across species.
- Vernon Mountcastle argued in 1978 that the whole neocortex runs on the same common cortical algorithm.
- If the optic nerve is rewired to a different cortical region, that region becomes a visual area; blind people's visual cortex gets repurposed.
- Hawkins says he wakes in the middle of the night and stays awake an hour in a half-sleep state to think through these problems.
- He tests his theory of place cells by navigating his house to the bathroom with eyes closed, estimating his accumulating error.
- Real neurons can have 5,000 to 30,000 synapses, but about 95 percent are too far from the cell body to fire it individually.
- Charles Babbage invented the computer in the 1800s and was largely forgotten until much later.
- Color does not exist in the world; the brain only receives axons firing at rates correlated with light frequency.
- In phantom limb syndrome, amputees feel and can move a non-existent arm, showing the brain holds a model of the body that may not match reality.