Definition
Neural plasticity is the brain's capacity to physically change itself in response to experience. The brain is not fixed hardware running variable software; the hardware itself rewires. Every lasting memory, learned skill, and recovered function is a structural change in neural tissue.
Behave uses plasticity to dismantle a stubborn intuition — that biology is destiny. Genes and early life matter enormously, but the brain that experiences the world is reshaped by it, continuously, into adulthood.
Why it matters
How it works
Plasticity operates at several scales. At the synapse, connections strengthen with use and weaken with disuse, following the principle that neurons which fire together wire together. Beyond synapses, neurons can grow new dendritic branches, the brain can recruit regions for new tasks after damage, and even new neurons can be born in certain regions throughout life.
Sapolsky stresses that plasticity is neutral about outcomes. Practising a skill, surviving chronic stress, or enduring trauma all sculpt the brain — sometimes adaptively, sometimes harmfully. This is why the same prolonged stress that reshapes a hippocampus shows up later as a measurable change in behavior. The brain you have is a record of the life you have lived.