Rewiring the Brain

Language is one of the most experience-dependent human abilities, but 'neuroplasticity' is often used as a slogan or assumed to be a mechanism. Research in the developmental, bilingual, clinical and neuromodulation fields has developed in parallel, with few syntheses that critically address methodology. This critical review asks which neural principles link plasticity to language and how reliably they can be measured, what the evidence shows for language growth and disorder recovery, and how strong the evidence is for interventions that harness plasticity. Studies were identified through keyword searches prioritising meta-analyses, randomised trials and longitudinal studies, and appraised for sample size, design, controls, measurement reliability and replication. The dual-stream model that has superseded the classical Broca-Wernicke model, and network-based accounts emphasising flexible redistribution across language-selective and domain-general areas offer the best theoretical basis, though neuroimaging inference is limited by small samples, poor reliability and reverse inference. In language growth, conversational experience is related to left inferior frontal activity in children; grammatical learning declines gradually after late adolescence; bilingualism is associated with structural changes while the behavioural bilingual advantage is less robust; and ageing involves maintenance, reserve and compensation. Post-stroke aphasia shows most recovery in the first year; evidence of plasticity in dyslexia, developmental language disorder and primary progressive aphasia remains limited. Intensive speech-language therapy has the strongest support; transcranial stimulation shows low-certainty effects; and speech neuroprostheses involve few participants with paralysis rather than aphasia. The review recommends preregistered, longitudinal trials, individualised functional mapping, and early, intensive rehabilitation and language-rich environments.