How to Improve at Learning Using Neuroscience & AI | Dr. Terry Sejnowski

KEYPOINTS

• 01

  The brain learns actions by predicting the next reward

  Sejnowski, a computational neuroscientist and PhD physicist, says the algorithm the brain uses to learn sequences of actions toward a goal was worked out theoretically in the 1990s and later confirmed with neuron recordings and human imaging. You predict the reward an action will bring, compare it with what you actually get, and use the difference to adjust synapses. Over a lifetime this builds a 'value function' of what is good or bad for you, such as knowing what to order at a restaurant.

• 02

  The same algorithm powered AlphaGo

  In AI this is reinforcement learning, the approach DeepMind used to beat the world Go champion. Sejnowski notes Go is to chess what chess is to checkers in difficulty, because many battles unfold across the board at once.

• 03

  Basal ganglia loops run both movement and thinking

  The basal ganglia form loops with the motor cortex for actions and with the prefrontal cortex for thinking. The prefrontal loop is among the last to mature, in early adulthood. Sejnowski says adolescents' 'no-go' circuitry often doesn't yet kick in to stop actions that aren't in their interest.

• 04

  Procedural learning beats book learning for fast, expert skills

  Cognitive learning is step-by-step and inefficient; procedural learning becomes automatic. You can't learn tennis from a book. As a physicist, Sejnowski says solving problem sets, not memorizing equations, made him competent. Huberman adds that knowing the mechanism behind a protocol and then practicing it reinforces both.

• 05

  Sleep spindles move the day's learning into long-term memory

  Recording from epilepsy patients who spend about two weeks in hospital with brain electrodes, Sejnowski's team found spindles (bursts of 1–2 seconds in non-REM transitional stages) traveling in circles around the cortex. Spindles help consolidate the hippocampus's replay of daytime experience into cortical storage. Getting enough sleep is the first lever, and the two discuss research linking daytime exercise to more spindles.

• 06

  Every brain hack has a cost

  The Ambien finding (below) shows you 'don't get anything for free.' Huberman extends the point: low-dose testosterone therapy can bring vigor but is like a second puberty, and puberty is one of the fastest phases of aging. Growth hormone can likewise give vigor while visibly aging skin. He says he is neither for nor against them; responses are highly individual.

• 07

  Aging thins connections but preserves old memories

  Infants overproduce synapses and then prune them because synapses are energetically expensive. Pruning slows but continues with age, so the cortex thins. Memories laid down young remain 'rock solid' and form the foundation for later learning, and adults can still learn, if less quickly.

• 08

  Mitochondria explain falling vigor, and exercise restores it

  With age, mitochondria become fewer and less efficient, so learning costs more energy. Some prescription drugs can also harm mitochondria. Sejnowski calls exercise 'the best drug you could ever take' because it benefits every organ, including the brain. He runs on the beach below the Salk Institute daily and climbs back up the roughly 340-foot cliff.

• 09

  Ketamine reveals a glutamate side of schizophrenia

  Ketamine blocks NMDA glutamate receptors and reduces inhibitory interneuron signaling, raising cortical excitation. People who use it at parties two days in a row can arrive at emergency rooms in full psychosis, with auditory hallucinations and paranoia indistinguishable from a schizophrenic break, which resolves after a couple of days of isolation. Sejnowski believes large language models could have flagged this connection 20 years earlier.

• 10

  Parkinson's alters the sense of speed

  Dopamine neurons, which carry the reward-prediction signal for procedural learning, are vulnerable to toxins such as pesticides. When the first L-DOPA trials began, people who had been 'locked in' started talking again. Parkinson's patients who move slowly feel they are moving fast, yet they can move at normal speed if asked, suggesting the brain's internal set point for speed has shifted.