Studying the default mode and its mindfulness-induced changes using EEG functional connectivity.

The default mode network (DMN), typically studied with brain imaging, was investigated using electroencephalography (EEG) functional connectivity (FC) during mindfulness meditation (MM). Three groups of meditators were compared with controls. DMN activity appeared as reduced overall inter-hemispheric gamma mean phase coherence (MPC) when transitioning from rest to a time production task. MM produced a state increase in alpha MPC and a trait decrease in EEG-FC, regardless of expertise or band. Specifically, reductions occurred in right theta MPC and left alpha and gamma MPC. Left gamma MPC negatively correlated with MM expertise, possibly reflecting lower internal verbalization. The lower gamma MPC supports the idea that MM reduces DMN activity related to self-reference and mind-wandering.

Study at a glance

Abstract

The default mode network (DMN) has been largely studied by imaging, but not yet by neurodynamics, using electroencephalography (EEG) functional connectivity (FC). mindfulness meditation (MM), a receptive, non-elaborative training is theorized to lower DMN activity. We explored: (i) the usefulness of EEG-FC for investigating the DMN and (ii) the MM-induced EEG-FC effects. To this end, three MM groups were compared with controls, employing EEG-FC (-MPC, mean phase coherence). Our results show that: (i) DMN activity was identified as reduced overall inter-hemispheric gamma MPC during the transition from resting state to a time production task and (ii) MM-induced a state increase in alpha MPC as well as a trait decrease in EEG-FC. The MM-induced EEG-FC decrease was irrespective of expertise or band. Specifically, there was a relative reduction in right theta MPC, and left alpha and gamma MPC. The left gamma MPC was negatively correlated with MM expertise, possibly related to lower internal verbalization. The trait lower gamma MPC supports the notion of MM-induced reduction in DMN activity, related with self-reference and mind-wandering. This report emphasizes the possibility of studying the DMN using EEG-FC as well as the importance of studying meditation in relation to it.