Common and distinct lateralised patterns of neural coupling during focused attention, open monitoring and loving kindness meditation

Abstract

Meditation has been integrated into different therapeutic interventions. To inform the evidence-based selection of specific meditation types it is crucial to understand the neural processes associated with different meditation practices. Here we explore commonalities and differences in electroencephalographic oscillatory spatial synchronisation patterns across three important meditation types. Highly experienced meditators engaged in focused attention, open monitoring, and loving kindness meditation. Improving on previous research, our approach avoids comparisons between groups that limited previous findings, while ensuring that the meditation states are reliably established. Employing a novel measure of neural coupling - the imaginary part of EEG coherence - the study revealed that all meditation conditions displayed a common connectivity pattern that is characterised by increased connectivity of (a) broadly distributed delta networks, (b) left-hemispheric theta networks with a local integrating posterior focus, and (c) right-hemispheric alpha networks, with a local integrating parieto-occipital focus. Furthermore, each meditation state also expressed specific synchronisation patterns differentially recruiting left- or right-lateralised beta networks. These observations provide evidence that in addition to global patterns, frequency-specific inter-hemispheric asymmetry is one major feature of meditation, and that mental processes specific to each meditation type are also supported by lateralised networks from fast-frequency bands.

Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1

Grand average of the imaginary part of coherence (ICoh) as a function of frequency pooled for all investigated electrode combinations during resting state (REST), focused attention meditation (FAM), open monitoring meditation (OMM), and loving kindness meditation (LKM).

Figure 2

Schematic presentations of electrodes (in grey) and clusters used for analyses marked as C1, C2, C3, C4, C1-C2, C3-C4, C1-C3, C2-C4, C1-C4, and C2-C3. Electrodes in C1: F7, F5, F3, F1, FC5, FC3, FC1, C5, C3, C1; Electrodes in C2: F8, F6, F4, F2, FC6, FC4, FC2, C6, C4, C2; Electrodes in C3: CP5, CP3, CP1, P7, P5, P3, P1, PO7, PO5, O1; Electrodes in C4: CP6, CP4, CP2, P8, P6, P4, P2, PO8, PO6, O2. Inter- and intra-hemispheric connectivity is reflected by cluster-based measures of ICoh (mean of all electrode pairs between C1 and C2 for C1-C2, mean between all electrode pairs between C1 and C3 for C1-C3, etc.).

Figure 3

Schematic illustration of statistically significant differences in the re-distribution of strongest and weakest connections (reflected by ICoh) between the respective meditation state (FAM, OMM, LKM) and resting state for clusters in delta, theta, slow alpha, fast alpha, and beta frequency ranges. Blue colour indicates meditation-related increase (statistically significant, Bonferroni corrected, p < 3.10−4 - continuous line; trend, Bonferroni corrected, 3.10−4 < p < 3.10−2 - dashed line). Circles designate within-cluster (C1, C2, C3, C4) comparisons, lines designate intra- and inter-hemispheric comparisons for C1-C3, C1-C2, C3-C4, etc.

Figure 4

(A) Mean values ± standard error of ICoh difference between REST and respective meditation conditions (FAM, OMM and LKM) pooled together, for theta, alpha 1 and alpha 2 frequency bands for left-hemisphere clusters (C1, C3, and C1-C3) and right-hemisphere clusters (C2, C4, and C2-C4). Left vs. Right asymmetry common for all meditation conditions is illustrated. (B) Mean values ± standard error of ICoh difference between REST and respective meditation conditions (FAM, OMM and LKM) for the beta frequency range for left-hemisphere clusters C1, C3, and C1-C3 pooled together, and right-hemisphere clusters C2, C4, and C2-C4 pooled together. Left vs. Right asymmetry differentiating the three meditation conditions is illustrated.

Figure 5

Topography maps of grand average integrated connectivity (IC) presented as a difference between REST and the respective meditation condition (FAM, OMM, and LKM) for three frequency ranges (theta, alpha 2, and beta), which showed systematic differences. Blue colour indicates meditation-related increase; red colour indicates meditation-related decrease.