Neuroplasticity, the brain's capacity to change its structure and function in response to experience, is not restricted to early development. It operates throughout the lifespan, and the activities that engage it include forms of deliberate mental training. In 2005, Sara Lazar at Harvard Medical School published a study using structural MRI to compare the brains of experienced meditators to non-meditating adults of similar age and background. The meditators showed significantly greater cortical thickness in the prefrontal cortex and right anterior insula, regions associated with attention, interoception, and emotional regulation.
The MBSR Evidence Base
Mindfulness-Based Stress Reduction, an 8-week programme developed by Jon Kabat-Zinn, is the most extensively researched mindfulness intervention. A 2011 study by Britta Holzel and colleagues found that 8 weeks of MBSR produced measurable increases in grey matter density in the left hippocampus, posterior cingulate cortex, and cerebellum, and decreases in grey matter density in the right amygdala in the direction of reduced emotional reactivity. These structural changes correlated with participants' self-reported reductions in stress.
What Mindfulness Does to the Default Mode Network
The default mode network is active when the mind is not engaged in a specific task and characteristically produces mind-wandering, self-referential rumination, and the kind of repetitive thought loops associated with anxiety and low mood. Mindfulness practice consistently reduces default mode network activity and strengthens connections between the prefrontal cortex and the salience network, improving the capacity to notice mind-wandering and redirect attention. This is the neurological mechanism behind the widely reported reduction in rumination associated with consistent meditation practice.
Sources
- Lazar, S.W., et al. (2005). Meditation experience is associated with increased cortical thickness. NeuroReport, 16(17), 1893-1897.
- Holzel, B.K., et al. (2011). Mindfulness practice leads to increases in regional brain gray matter density. Psychiatry Research: Neuroimaging, 191(1), 36-43.
- Brewer, J.A., et al. (2011). Meditation experience is associated with differences in default mode network activity and connectivity. Proceedings of the National Academy of Sciences, 108(50), 20254-20259.