Britta K. Hölzel et al., “How Does Mindfulness Meditation Work? Proposing Mechanisms of Action From a Conceptual and Neural Perspective” (Perspectives on Psychological Science, 2011) here:
Several neuroscientific studies have reported the ACC to be implicated in meditation (Cahn & Polich, 2006). Using functional MRI (fMRI), Holzel et al. (2007) pursued the question of which brain region would be distinctly activated when meditators performed focused attention meditation.
Compared with age-, gender-, and education-matched controls, experienced meditators showed greater activation in the rostral ACC (Holzel et al., 2007), suggesting an effect of meditation practice on ACC activity.
A similar effect (greater rostral ACC activation in meditators compared with controls) was identified when individuals engaged in a mindfulness practice while awaiting unpleasant electric stimulation (Gard et al., 2010).
Five days of Integrative Body-Mind Training may lead to greater activation of the rostral ACC during the resting state (Tang et al., 2009).
Although ACC activation might initially be enhanced when acquiring greater attentional control, it might later decrease with higher levels of expertise, when the focus of attention is so steady that monitoring distractions becomes superfluous (Brefczynski-Lewis, Lutz, Schaefer, Levinson, & Davidson, 2007).
In addition to these functional findings, structural MRI data also indicate that meditation practice might exert an influence on the ACC.
Cortical thickness in the dorsal ACC was greater in experienced meditators compared with control subjects in an analysis of brain gray matter (Grant, Courtemanche, Duerden, Duncan, & Rainville, 2010), and 11 hr of Integrative Body-Mind Training led to an increase in white matter integrity in the ACC (Tang et al., 2010).
In line with the assumption that ACC function is strengthened through concentrative meditation, electroencephalogram data document increased frontal midline theta rhythm during meditation (Aftanas & Golocheikine, 2002; Kubota et al., 2001).
Frontal midline theta is associated with attention demanding tasks and presumably reflects ACC (and medial prefrontal cortex) activity (Asada, Fukuda, Tsunoda, Yamaguchi, & Tonoike, 1999).
Conclusion:
“Mindfulness as a state, trait, and clinical intervention has been extensively researched over the last two decades; however, knowledge of the underlying mechanisms of mindfulness is still in its infancy. Future work should identify additional components of mindfulness and establish to what extent the components described in this article are truly distinct mechanisms or how they can be integrated into fewer components. We believe that it will be necessary both to further differentiate each component and to further integrate them into a comprehensive model. This future empirical work is critical in order to optimally apply mindfulness in the clinical domain and to advance techniques that aim at cultivating a healthy mind and increased well-being.”
See also: Can people change their brains and behaviour through meditation?
Hat tip: Stephanie West Allen at Brains on Purpose