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Brain plasticity refers to the brain’s capacity to reorganize its structure and function, both during natural development and in response to injury. Neurons communicate through synapses, and increases in both neuron and synapse numbers underpin plastic changes.
Infants exhibit the highest degree of plasticity. Between birth and age 2–3, synapses per neuron surge from roughly 2,500 to 15,000, giving toddlers twice the synaptic density of adults.
During adolescence, the brain undergoes synaptic pruning—eliminating unused connections while retaining those reinforced by experience. By late adolescence, the total number of synapses is roughly halved compared to early childhood.
Contrary to earlier assumptions that the adult brain is static, learning and new experiences can still generate new synapses and strengthen existing ones. Remarkably, dendritic branching often increases in older adults relative to middle‑aged individuals, supporting continued adaptability.
Traumatic events such as stroke or accidents trigger compensatory plasticity. Although neuron count remains largely unchanged, the efficacy of remaining connections can improve, aiding functional recovery.
