In one experienced compassion meditator, generating feelings of love and compassion while reciting a mantra activated the left medial prefrontal cortex extending to the anterior cingulate gyrus, as well as the right caudate body extending to the right insula and the left midbrain near the hypothalamus. These brain areas are involved with empathy and pleasant feelings, supporting the hypothesis that compassion meditation engages neural circuits related to social emotions.
A review of 28 neuroimaging studies on meditation published between 2016 and 2019 identifies four intention-based dimensions of meditation practice: focusing on the present moment, cultivating wholesome qualities, avoiding unwholesome qualities, and adopting certain attitudes. Half of the studies did not assess participants' subjective experience. The findings relate meditation-related brain function to cognitive, affective, somatic, and self domains, with most studies describing results in terms of brain processes. The authors recommend five improvements for future research: providing clear definitions, including measures of subjective experience, correctly assessing processes, combining methodologies, and avoiding overinterpretation.
The default mode network (DMN) is a set of brain regions that activate together during mind wandering, self-reflection, and considering others' perspectives. Abnormal DMN activity correlates with symptom severity in mental disorders, suggesting it could serve as a biomarker for diagnosis and for assessing pharmacological treatments. Meditation practice also modulates the DMN, and meditation is increasingly recognized as beneficial for treating mental disorders. The authors propose using DMN measures as a biomarker to monitor the therapeutic effects of meditation in mental disorders, noting recent findings support this approach.
Moderately experienced meditators with less than two years of practice show significant activation in the hippocampus and parahippocampal formations during silent mantra meditation, as measured by functional magnetic resonance imaging. Activation also occurred in the middle cingulate cortex and precentral cortex, but not in the anterior cingulate cortex, and only small clusters appeared in the prefrontal cortex. The findings suggest that hippocampal activation occurs early in meditation practice and across different meditation styles, including relaxation. The authors propose further research to clarify whether this hippocampal activity relates to memory consolidation.