Some of the most important work of protecting the brain may depend on immune and other cell types, which make up a surprising 50% of the human brain. In this special Beyond Lab Walls video podcast episode—part of the Salk Institute’s 2026 Year of Brain Health—Salk President Gerald Joyce, MD, PhD, speaks with Nicola Allen, PhD, a leading neuroscientist whose lab studies how non-neuronal brain cells shape brain function in health, aging, and disease.