Differing regions of the human brain work in tandem to form large-scale integrated brain networks. Three large-scale brain region networks organize much of human brain activity: the Central Executive Network (CEN), the Salience Network (SN), and the Default Mode Network (DMN).

The CEN is dominant when we are deliberately focusing on a task, the SN is dominant when we are evaluating sensory input in preparing to respond, and the DMN is dominant when we are off-task and mind-wandering. 

These networks are relevant to mindfulness meditation which involves deliberate attentional focus (CEN) on bodily sensations (SN) that minimizes mind-wandering (DMN). Much of the research on the effect of mindfulness meditation training on these brain networks is limited by small sample sizes, correlational findings, and the lack of control groups. 

Bremer et al. [Scientific Reports] tested the longitudinal effect of mindfulness training on the functional connectivity between these brain networks using functional magnetic resonance imaging (fMRI) with adult participants.

The researchers assigned 46 German meditation-naïve adults (50% male; average age = 35) to 31 days of either web-based mindfulness or health education training. Initial assignment was random, but researchers slightly adjusted the assignments to equalize the sex and age of the groups.

Participants underwent resting-state fMRI brain scans before and after intervention. Trainings involved daily 10-15-minute audio and video content. Mindfulness training was developed by a MBSR instructor. Health training involved excerpts from popular science broadcasts on a broad array of health topics. Participants needed to complete at least 23 sessions to be included in the data analysis. 

fMRI data were analyzed for functional connectivity, dynamic functional connectivity, and seed-based connectivity. Functional connectivity measures how much two brain networks are interconnected at a given time. Dynamic functional connectivity measures how much connectivity between networks fluctuates in tandem over time. Seed-based connectivity measures how regions of interest interact with the whole brain.

While the functional connectivity analysis showed no significant effects, the dynamic functional connectivity analysis showed the mindfulness training group had increased dynamic functional connectivity between regions of the DMN and regions of the SN while controls did not.

Seed-based connectivity analysis (using the DMN and SN regions identified in the prior analysis as seeds) found similar increases in connectivity between regions of the DMN and SN in the mindfulness group but not controls. 

The researchers interpret this greater functional connectivity as reflecting an individual’s growing awareness of when they are mind-wandering during mindfulness practice and using that awareness as a signal to return to focusing.

This study shows an increased DMN-SN dynamic functional connectivity after mindfulness training in naïve meditators. These brain findings offer some neural function correlates of how meditators track mind-wandering and re-focus attention.

The researchers caution that focused-attention and open-monitoring meditations would probably result in different patterns of connectivity. 

Reference:

Bremer, B., Wu, Q., Mora Álvarez, M. G., Hölzel, B. K., Wilhelm, M., Hell, E., Tavacioglu, E. E., Torske, A., & Koch, K. (2022). Mindfulness meditation increases default mode, salience, and central executive network connectivity. Scientific Reports.

Link to study