How does the brain transform experiences into lasting memories? Neuroscientist Marlene Bartos studies two key neuron types that control learning. Principal cells store information, while inhibitory neurons regulate and fine-tune their activity. Their interaction determines which signals become stable memories. Also on the show: Do IQ tests really measure intelligence? Plus: We follow the release of lynx back into the wild, join an avalanche researcher studying dangerous snowpacks, and accompany a geologist searching for natural white hydrogen deep beneath the Alps.