How does meditation affect the brain?

The University of Pittsburgh examined the brains of long-time meditators specifically when they were not meditating. MRI scans show that after an eight-week course of mindfulness practice, the brain’s ‘fight or flight’ center, the amygdala, appears to shrink. This primal region of the brain, associated with fear and emotion, is involved in the initiation of the body’s response to stress. As the amygdala shrinks when meditators heard the sounds of people suffering, they had stronger activation levels in their temporal parietal junctures, a part of the brain tied to empathy, than people who did not meditate. Mediators are more compassionate. The amygdala actually shrinks, and this correlates with the reduction in perceived stress.

Animals are able to turn their amygdala on and off. Gazelles are a good example; if a lion chases them, their amygdala begins firing, and this helps them get away from the predator. But as soon as the lion stops chasing them, the herd is back to grazing within five minutes. They need to eat, and so have learned to turn their amygdala off when they don’t need it. What we find in humans is the amygdala switches on, but because we have our imagination and we can think about all the future things that might go wrong, it doesn’t so easily switch off for many of us. We end up worrying about the future or brooding about the past. The amygdala is kept switched on for things that have not even happened yet – we can invent worries.

The pre-frontal cortex – associated with higher order brain functions such as awareness, concentration, and decision-making – becomes thicker. In addition, EEG research has shown that concentration and open monitoring meditations tend to deactivate the brain’s default mode network, whereas automatic self-transcending meditations activate it. The default mode network is sort of like a relaxed idling mode of the brain.

Functional magnetic resonance imaging (fMRI) has also been used to study meditation. This allows researchers to look more deeply into what’s happening in the brain and what the changes are. A pioneering study by Sara Lazar published in 2005 found that insight meditation increased the thickness of the brain’s cortex. There have been a number of studies since then that have found a similar result. This isn’t surprising, and many other activities, such as playing a musical instrument, have been shown to change the brain. Again, the particular approach to meditation has a bearing on what part of the brain is affected.