David Eagleman: Neuroplasticity and the Livewired Brain | Lex Fridman Podcast #119

Eagleman argues the brain is best understood not through the hardware/software metaphor but as 'livewear': a system that physically reconfigures itself throughout life. He explains that different brain regions harden at different rates depending on how stable their input data is, and that plasticity persists into old age, driven largely by relevance and motivation. The conversation ranges across brain-computer interfaces (where he is skeptical of invasive approaches), the 'potato head' theory that the brain can absorb data from any sensor, free will, in-group/out-group neuroscience, the limits of GPT-3, and his own company Neosensory, which feeds sound and other data streams to the brain through vibrations on the skin. He closes with book recommendations and advice to young people to stay adaptable.

• Eagleman notes children under about seven can have an entire brain hemisphere removed (hemispherectomy) and still function nearly normally.
  00:06:14
• He explains he chose 'livewired' over 'plasticity' because the brain never reaches an endpoint, it rewires constantly your whole life.
  00:10:54
• He is openly skeptical that invasive brain-computer interfaces like Neuralink will become a mainstream consumer business.
  00:26:18
• Using the Kalahari-bushman-and-radio analogy, he speculates free will might have a source outside the visible machinery of the brain.
  00:48:35
• His lab's brain-scan study showed people empathize more with in-group hands being stabbed, even with arbitrary coin-toss tribes.
  00:54:13
• He predicts GPT-3 will never do a really good job because it has no model of what it's like to be a human.
  01:08:10
• He reveals he gave up his lab and spends 90% of his time running Neosensory, calling it the most important thing happening right now.
  01:21:35

• The visual cortex hardens quickly because visual data is stable, while motor and somatosensory cortex stay malleable because the body keeps changing.
  00:12:26
• An alligator's brain is essentially the same now as 100,000 years ago, whereas humans drop into the world with a 'half-baked' brain to absorb culture.
  00:14:31
• Hundreds of thousands of people already hear and see via cochlear and retinal implants that speak 'the dialect of silicon valley,' not biology.
  00:30:53
• Some people with physical Alzheimer's damage show no symptoms while alive because constant cognitive challenge builds new neural roadways.
  00:36:33
• Each neuron contains the entire human genome, and the brain has roughly half a quadrillion connections.
  00:46:30
• The Mars rover Curiosity effectively died when a wheel got stuck, while a wolf simply gnaws off a trapped leg and relearns to walk.
  01:15:21
• Neosensory's wristband lets deaf people 'hear' through skin vibrations, becoming a new qualia, for $399, far cheaper than a cochlear implant.
  01:22:37
• Eagleman has tested sensory expansion, feeling infrared and ultraviolet, and once located a hidden night-vision camera by following the sensation on his wrist.
  01:31:23