Brain plasticity

Neuroplasticity, also known as brain plasticity or neural plasticity, is an umbrella term that describes lasting change to the brain throughout an individual's life course. The term gained prominence in the latter half of the 20th century, when new research showed that many aspects of the brain can be altered (or are "plastic") even into adulthood. This notion is in contrast with the previous scientific consensus that the brain develops during a critical period in early childhood and then remains relatively unchanged (or "static").

Neuroplasticity can be observed at multiple scales, from microscopic changes in individual neurons to larger-scale changes such as cortical remapping in response to injury. However, cortical remapping is more extensive early in development. Behavior, environmental stimuli, thought, and emotions may also cause neuroplastic change through activity-dependent plasticity, which has significant implications for healthy development, learning, memory, and recovery from brain damage.

At the single cell level, synaptic plasticity refers to changes in the connections between neurons, whereas non-synaptic plasticity refers to changes in their intrinsic excitability.

From the late 1500s neurologists largely supported the theory of localizationism, which holds that the brain comprises functionally specialized areas. The famed astronomer Galileo Galilei is credited with the origins of localizationism. According to Norman Doidge, Galileo's studies of space and its celestial bodies led him to believe that "all nature functioned as a large cosmic clock" and that these bodies "began to explain individual living things, including our bodily organs, mechanistically". He saw the universe as a giant machine rather than as a living organism. When applied to the brain, this means that its parts have hardwired functions as a machine has parts designated to a certain area. According to this theory, the functional specialization of each brain area could mean that localized damage to one area would lead to a loss of the function that it served. This led physicians to consider certain diseases or conditions arising from brain damage as untreatable.

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