The Brain That Rewires Itself
For decades the adult brain was thought to be fixed. It is not. Neuroplasticity is the brain's lifelong ability to change its structure and function in response to experience, learning, and injury. Several mechanisms drive it.
At the level of connections, learning strengthens the synapses that fire together — a process called long-term potentiation (LTP), often summarized as "cells that fire together, wire together." Conversely, unused connections are removed through synaptic pruning, which is especially dramatic in childhood and adolescence: the brain sculpts an efficient network by discarding what it does not use.
At a larger scale, the cortex can remap: when one region is deprived of input (say, after the loss of a limb or of sight), neighboring regions can take over its territory, reassigning cortical real estate. And contrary to old dogma, the adult brain retains some neurogenesis — the birth of new neurons — notably in the hippocampus, supporting new learning and memory.
Plasticity is greatest in early development (the critical and sensitive periods), when experience most powerfully shapes the wiring, but it never fully stops. It is the biological basis of learning itself, and of recovery after brain injury.
Common pitfall: believing neuroplasticity ends in childhood. Plasticity is greatest early in life, but it continues throughout adulthood — the adult brain keeps forming, strengthening, and pruning connections (and even growing some new neurons) as long as it keeps learning.