Network-based characterization of brain functional connectivity in Zen practitioners

Abstract

In the last decade, a number of neuroimaging studies have investigated the neurophysiological effects associated with contemplative practices. Meditation-related changes in resting state functional connectivity (rsFC) have been previously reported, particularly in the default mode network, frontoparietal attentional circuits, saliency-related regions, and primary sensory cortices. We collected functional magnetic resonance imaging data from a sample of 12 experienced Zen meditators and 12 meditation-naïve matched controls during a basic attention-to-breathing protocol, together with behavioral performance outside the scanner on a set of computerized neuropsychological tests. We adopted a network system of 209 nodes, classified into nine functional modules, and a multi-stage approach to identify rsFC differences in meditators and controls. Between-group comparisons of modulewise FC, summarized by the first principal component of the relevant set of edges, revealed important connections of frontoparietal circuits with early visual and executive control areas. We also identified several group differences in positive and negative edgewise FC, often involving the visual, or frontoparietal regions. Multivariate pattern analysis of modulewise FC, using support vector machine (SVM), classified meditators, and controls with 79% accuracy and selected 10 modulewise connections that were jointly prominent in distinguishing meditators and controls; a similar SVM procedure based on the subjects’ scores on the neuropsychological battery yielded a slightly weaker accuracy (75%). Finally, we observed a good correlation between the across-subject variation in strength of modulewise connections among frontoparietal, executive, and visual circuits, on the one hand, and in the performance on a rapid visual information processing test of sustained attention, on the other. Taken together, these findings highlight the usefulness of employing network analysis techniques in investigating the neural correlates of contemplative practices.

Dynamic interactions of the cortical networks during thought suppression

“…IC23, another marginally Suppression-related component, was the only one that significantly involved the insular cortices. This insular activation has been reported in both thought suppression and inhibition studies (Krmpotich et al 2013;Kemmer et al 2015;Lin et al 2015;Rigon et al 2015) but lacks an established interpretation. This area has been implicated in a wide variety of functions (Corbetta et al 1998), including mental imagery (Mellet et al 1996;Kosslyn and Thompson 2003;Ganis et al 2004;Mazard et al 2004;Sack et al 2008).…”

Signal or noise: brain network interactions underlying the experience and training of mindfulness

“…The inconsistency across findings that is typical for this literature is well illustrated by the three significant findings identified for FC between the default and executive networks. Whereas two studies found increased FC between the dlPFC and regions of the default network (PCC and mPFC/ACC, respectively), one study using independent component analysis found decreased FC between the entire default and executive networks . These findings are not exact contradictions, but the pattern of both increased and decreased FC is difficult to reconcile.…”

“…Whereas two studies found increased FC between the dlPFC and regions of the default network (PCC and mPFC/ACC, respectively), one study using independent component analysis found decreased FC between the entire default and executive networks. 25,27,79 These findings are not exact contradictions, but the pattern of both increased and decreased FC is difficult to reconcile. A likely explanation for this divergence is the diversity of methods employed.…”

The brain on silent: mind wandering, mindful awareness, and states of mental tranquility

“…31), recent cross-sectional fc studies of meditators have generally demonstrated increased connectivity between the two main nodes of the DMN (PCC and vmPFC) and between nodes of the DMN and salience and executive networks during a nonmeditative resting state. 109,111,114,[129][130][131][132] These studies reflect changes that are sustained in nonmeditative states. In a small number of studies, increased fc has been found between DMN nodes and task-positive regions (e.g., dACC, dlPFC) during and across styles of meditation practice (Fig.…”