Sergio Elías Hernández 1 , Alfonso Barros-Loscertales 2 , Yaqiong Xiao 3 , José Luis González-Mora 4 , Katya Rubia 5 Affiliations expand PMID: 29275207 DOI: 10.1016/j.neuroscience.2017.12.017 Free article
Abstract
Some meditation techniques teach the practitioner to achieve the state of mental silence. The aim of this study was to investigate brain regions that are associated with their volume and functional connectivity (FC) with the depth of mental silence in long-term practitioners of Sahaja Yoga Meditation. Twenty-three long-term practitioners of this meditation were scanned using Magnetic Resonance Imaging. In order to identify the neural correlates of the depth of mental silence, we tested which gray matter volumes (GMV) were correlated with the depth of mental silence and which regions these areas were functionally connected to under a meditation condition. GMV in medial prefrontal cortex including rostral anterior cingulate cortex were positively correlated with the subjective perception of the depth of mental silence inside the scanner. Furthermore, there was significantly increased FC between this area and bilateral anterior insula/putamen during a meditation-state specifically, while decreased connectivity with the right thalamus/parahippocampal gyrus was present during the meditation-state and the resting-state. The capacity of long-term meditators to establish a durable state of mental silence inside an MRI scanner was associated with larger gray matter volume in a medial frontal region that is crucial for top-down cognitive, emotion and attention control. This is furthermore corroborated by increased FC of this region during the meditation-state with bilateral anterior insula/putamen, which are important for interoception, emotion, and attention regulation. The findings hence suggest that the depth of mental silence is associated with medial fronto-insular-striatal networks that are crucial for top-down attention and emotional control.
Introduction: While cross-sectional studies have shown neural changes in long-term meditators, they might be confounded by self-selection and potential baseline differences between meditators and non meditators. Prospective longitudinal studies of the effects of meditation in naïve subjects are more conclusive with respect to causal inferences, but related evidence is so far limited.
Methods: Here, we assessed the effects of a 4-week Sahaja Yoga meditation training on gray matter density and spontaneous resting-state brain activity in a group of 12 meditation-naïve healthy adults.
Results: Compared with 30 control subjects, the participants to meditation training showed increased gray matter density and changes in the coherence of intrinsic brain activity in two adjacent regions of the right inferior frontal gyrus encompassing the anterior component of the executive control network. Both these measures correlated with self-reported well-being scores in the meditation group.
Conclusions: The significant impact of a brief meditation training on brain regions associated with attention, self-control, and self-awareness may reflect the engagement of cognitive control skills in searching for a state of mental silence, a distinctive feature of Sahaja Yoga meditation. The manifold implications of these findings involve both managerial and rehabilitative settings concerned with well-being and emotional state in normal and pathological conditions.
(a) Spatial contiguity between the right inferior frontal clusters showing increased GM density (in blue) and a modulation of coherent activity (in red) after meditation training. The overlap between morphometric and resting‐state data is shown in green. (b) Spectral power of intrinsic activity in the executive control network, providing a measure of the contribution of each frequency bin (between 0 and 0.25 Hz) to the fluctuations of BOLD signal at rest (asterisks indicate the frequency bins displaying a significant effect in time‐by‐group interaction). Meditators, compared with non meditators, display a reduction of power at ultra‐low frequencies, and an increase at low–middle frequencies, after training. (c) Average GM density in the cluster resulting from VBM interaction analysis for the two time points of both training (MG) and control (CG) groups (error bars depict standard deviations). Meditators, compared with non meditators, display a significant increase of GM density with training in the right fronto‐insular cluster depicted in green color in panel A
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Source: National Library of Medicine, National Center of Biotechnology Information, https://pubmed.ncbi.nlm.nih.gov/30485713/
