Gray Matter and Functional Connectivity in Anterior Cingulate Cortexare Associated with the State of Mental Silence During Sahaja YogaMeditation

Abstract—Some meditation techniques teach the practitioner to achieve the state of mental silence. The aim ofthis 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 theneural correlates of the depth of mental silence, we tested which gray matter volumes (GMV) were correlated withthe depth of mental silence and which regions these areas were functionally connected to under a meditation con-dition. GMV in medial prefrontal cortex including rostral anterior cingulate cortex were positively correlated withthe subjective perception of the depth of mental silence inside the scanner. Furthermore, there was significantlyincreased FC between this area and bilateral anterior insula/putamen during a meditation-state specifically, whiledecreased connectivity with the right thalamus/parahippocampal gyrus was present during the meditation-stateand the resting-state. The capacity of long-term meditators to establish a durable state of mental silence insidean 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 regionduring 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 medialfronto-insular-striatal networks that are crucial for top-down attention and emotional control