For most of the 20th century, scientists believed the adult brain was fixed and unchangeable. We now know that's profoundly wrong: the brain rewires itself throughout life in response to experience. This property — neuroplasticity — is the biological basis of all learning and a source of real hope.
Learning Objectives
- •Understand neuroplasticity
- •Learn how connections strengthen and prune
- •Understand adult neurogenesis
The brain rewires throughout life
NEUROPLASTICITY is the brain's lifelong ability to reorganize itself — forming, strengthening, and weakening connections — in response to how it's used. Learning a skill, recovering from injury, building a habit: all are neuroplasticity in action. The brain you have is shaped by the experiences you've had and the things you repeatedly do. It's not fixed hardware; it's continuously remodeled.
Fire together, wire together (LTP)
How do connections strengthen? Through a process captured by the phrase 'neurons that fire together, wire together'. When two neurons are repeatedly activated at the same time, the synapse between them STRENGTHENS — a mechanism called LONG-TERM POTENTIATION (LTP). This is the cellular basis of learning: practice physically strengthens the neural circuits you use, which is why repetition builds skill.
Use it or lose it: pruning
The flip side: connections you DON'T use weaken and get eliminated, a process called SYNAPTIC PRUNING. The brain is efficient — it invests in circuits you use and prunes away those you don't. This 'use it or lose it' dynamic is why skills fade without practice, and why continually challenging your brain matters: you're deciding which circuits to keep.
Neurogenesis: new neurons
Beyond rewiring existing connections, the adult brain can even grow NEW neurons (NEUROGENESIS), notably in the hippocampus (a memory hub). This was long thought impossible in adults. Neurogenesis is supported by exercise, learning, and good sleep — and suppressed by chronic stress. So your lifestyle influences not just how your brain is wired, but whether it's building new cells.
Why London taxi drivers have enlarged hippocampi
In a famous study, London taxi drivers — who must memorize the city's vast maze of streets — were found to have an enlarged posterior hippocampus (the region for spatial memory), and it grew with years of experience. It's a striking demonstration that intense, sustained mental practice physically reshapes the brain's structure. Neuroplasticity isn't abstract — it's measurable in brain anatomy.
Neuroplasticity, by the numbers
- ▸The brain rewires itself throughout life based on use (neuroplasticity)
- ▸'Fire together, wire together' — long-term potentiation (LTP) strengthens used connections
- ▸Unused connections are pruned ('use it or lose it')
- ▸The adult brain can grow new neurons (neurogenesis), supported by exercise and learning
The adult brain is fixed and cannot change.
The adult brain is remarkably plastic — it rewires throughout life, strengthens used connections, prunes unused ones, and can even grow new neurons. Learning, recovery, and habit change are all neuroplasticity at work.
Quick Check
What is neuroplasticity?
Quick Check
What does 'neurons that fire together, wire together' describe?
True or False
Sustained mental practice (like memorizing a city's streets) can physically enlarge brain regions.
Summary
- →Neuroplasticity: the brain rewires itself throughout life based on use
- →LTP ('fire together, wire together') strengthens used connections — the basis of learning
- →Unused connections are pruned — 'use it or lose it'
- →The adult brain can grow new neurons (neurogenesis), aided by exercise and learning
One of the most important things the plastic brain does is form memories. Next: how memory works.