principles of experience-dependent plasticity
If practice rewires the brain, the natural question is: what kind of practice, and how much? Researchers have distilled a set of plain principles that summarise when the brain actually changes in useful ways. They read almost like coaching rules, and they are the closest thing rehabilitation has to a recipe for driving recovery in the right direction.
A widely cited list includes: use it or lose it (skills and the circuits behind them fade without practice); use it and improve it (training a function can drive its improvement); specificity (the brain changes in line with exactly what you practise, so practising the real target matters); repetition matters (real rewiring needs many repetitions, not a token few); intensity matters (enough vigour and dose is needed to trigger change); time matters (different changes happen in different windows after injury); salience matters (the task must matter to the person — meaningful, motivating practice changes the brain more than boring drills); age matters (younger brains often change more readily); and transference and interference (practising one skill can help related skills, or unhelpful patterns can crowd out the ones you want). Together they explain why a few half-hearted, generic exercises rarely produce real recovery.
These principles are the backbone of modern, intensive, task-specific rehabilitation. They justify pushing for high repetition counts, meaningful and motivating activities, and practice that closely matches real life, rather than light, scattered, generic exercise. The honest caveat is that they were largely distilled from animal experiments and basic science, the ideal 'dose' for a given person and injury is still uncertain, and real patients are limited by fatigue, pain, and time — so the principles guide judgement; they are not exact prescriptions.
Designing therapy for a keen gardener after a stroke, the team uses the principles deliberately: many repetitions (repetition), of real gardening tasks she loves (salience and specificity), at a demanding dose (intensity), started early — instead of a handful of bland, generic arm lifts.
Meaningful, specific, high-repetition practice drives change better than bland exercise.
These principles come largely from animal and laboratory studies; the exact intensity, timing, and dose that work best for a particular human injury remain uncertain, and pain, fatigue, and time impose real limits. They guide therapy rather than dictating exact numbers.