It seems that at certain times, the brain is more amenable to change. These neuroplasticity windows open and then close especially during key periods in the brain’s development. The neurons and supporting cells have set up a “neuroplastic milieu”; an environment that will enthusiastically promote and support new synapse formation temporarily. In a classic study by Hubel and Wiesel in the 1970’s, a monkey had one eye sutured shut for the first 6 months of its life. Even when the eye was eventually opened, the monkey was essentially “blind” in that eye; not because it had any mechanical problems with the eye but the brain wiring required to process vision did not develop. This work led to the theory of “critical periods”. The brain requires the input from visual neurons at the right time for the right connections to be made. This is why children should have visual problems corrected very early in life. Another example of a critical period is during the learning of language. I remember reading stories of young children who were either severely isolated or essentially ‘feral’ who, once rescued, could only learn rudimentary language. It seems they missed the window for language acquisition. We know that young children (less than 5 years old) if frequently exposed to a language will adopt that language or languages as “mother tongue”.  Children who are older and exposed to the same intensive language immersion do not adopt that language as easily.

Another very important neuroplasticity window is during the first weeks after a brain injury. Neurons that die set off a series of events in surviving neurons that promote new synaptic connections…

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