In 1949, a Canadian psychologist with no patience for the strict behaviorism of his day proposed a rule for how connections between neurons change with experience — and used it to imagine how thought could emerge from cell assemblies firing in loops. That idea became "neurons that fire together, wire together," now one of neuroscience's most repeated phrases, even though Donald Hebb himself never wrote it quite that way. This episode follows Hebb from a childhood in Nova Scotia, through failed ambitions as a novelist, into a career that helped found a whole way of thinking about the mind — one whose fingerprints are now all over modern learning algorithms.

Dopamine has long been called the brain's pleasure chemical — the one that surges when you eat sugar or scroll through your phone. That story turns out to be mostly wrong. What dopamine neurons are actually doing is more surprising, and more mathematical. This episode traces how that discovery came together — through a neurophysiologist recording from monkey brains and a pair of computational neuroscientists who had been reading about reinforcement learning. It ends with how the same math is being used to understand depression and addiction.

Valentino Braitenberg spent decades studying how the brain is wired, convinced that anatomy, looked at carefully enough, reveals function. But he is best remembered for a slim 1984 book about imaginary robots that seemed to feel fear, show aggression, fall in love. This episode takes us into his world — a life that spanned continents, and a mind that refused to stay in one discipline.