Does Neuroplasticity Change Gray Or White Matter?

We all know that the brain is complex and constantly changing. But does neuroplasticity actually change the physical makeup of the brain? Does it make gray matter grow or shrink, or does it simply change the way neurons are wired together?

The answer, it turns out, is a bit of both. Neuroplasticity does both change the structure of gray matter and rearrange white matter connectivity. And these changes can happen quickly—within days or weeks—in response to experience or training.

For example, one study found that London taxi drivers who had been on the job for at least four years had more gray matter in the posterior hippocampus, a brain region important for spatial navigation, than novice taxi drivers or non-taxi driving controls. This difference in gray matter concentration was correlated with the number of years spent driving taxis.

Another study found that people who completed an eight-week mindfulness meditation training program had increased gray matter density in the hippocampus and decreases in gray matter density in the amygdala, a brain region important for anxiety and stress. These changes were correlated with participants’ self-reported improvements in mindfulness and decreased stress.

So neuroplasticity does indeed change gray matter, but it doesn’t necessarily do so by making more or less of it. Rather, it seems to be about changes in how gray matter is organized. And this can have big implications for how we think and behave.

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