Larger whole brain grey matter associated with long-term Sahaja Yoga Meditation: A detailed area by area comparison

Abstract

Objectives Our previous study showed that long-term practitioners of Sahaja Yoga Meditation (SYM) had around 7% larger grey matter volume (GMV) in the whole brain compared with healthy controls; however, when testing individual regions, only 5 small brain areas were statistically different between groups. Under the hypothesis that those results were statistically conservative, with the same dataset, we investigated in more detail the regional differences in GMV associated with the practice of SYM, with a different statistical approach. Design Twenty-three experienced practitioners of SYM and 23 healthy non-meditators matched on age, sex and education level, were scanned using structural magnetic resonance imaging (MRI). Their GMV were extracted and compared using Voxel-Based Morphometry (VBM). Using a novel ad-hoc general linear model, statistical comparisons were made to observe if the GMV differences between meditators and controls were statistically significant. Results In the 16 lobe area subdivisions, GMV was statistically significantly different in 4 out of 16 areas: in right hemispheric temporal and frontal lobes, left frontal lobe and brainstem. In the 116 AAL area subdivisions, GMV difference was statistically significant in 11 areas. The GMV differences were statistically more significant in right hemispheric brain areas. Conclusions The study shows that long-term practice of SYM is associated with larger GMV overall, and with significant differences mainly in temporal and frontal areas of the right hemisphere and the brainstem. These neuroplastic changes may reflect emotional and attentional control mechanisms developed with SYM. On the other hand, our statistical ad-hoc method shows that there were more brain areas with statistical significance compared to the traditional methodology which we think is susceptible to conservative Type II errors.

The Effect of Yoga Meditation Practice on Young Adults’ Inhibitory Control: An fNIRS Study

“…This suggests that participants in YoMed without having to react to unpredictable changes in the external environment, but simply focus on the stable environment in meditation, which may not have more impact on the reaction speed of participants. Therefore, we speculate that the reason why this study differs from the above studies in response time index may be that different YoMed practice methods were adopted in this study ( Hernandez et al, 2020 ).…”

Resting State Functional Connectivity Associated With Sahaja Yoga Meditation

“…Later on, Reva reported influences of SYM on event-related potentials sensitive to improvements in emotion processing (Reva et al, 2014). Our own research showed structural and functional differences in long-term practitioners of SYM relative to healthy non-meditators overlapping in the right inferior frontal cortex/insula, anterior cingulate cortex, and temporal cortex (Hernández et al, 2016(Hernández et al, , 2018(Hernández et al, , 2020, with structural differences extending further to the left inferior frontal cortex and right angular gyrus (Hernández et al, 2016(Hernández et al, , 2020. A recent study by Dodich et al (2019) found that, even after a short period (4 weeks) of SYM training, non-meditators demonstrated similar increased gray matter in the right inferior frontal cortex/insula and changes in the coherence of intrinsic brain activity in the right IFG and anterior parts of the executive control network, suggesting a direct association between SYM practice and these brain regions.…”

“…The volunteers had no physical or mental illness, no history of neurological disorders, and no addiction to nicotine, alcohol, or other drugs. All the SYM experts and non-meditator volunteers had participated in three of our previous studies (Hernández et al, 2018(Hernández et al, , 2020Dodich et al, 2019). The current analyses focuses on the resting-state FC acquisition that had not been previously reported.…”

“…The current analyses focuses on the resting-state FC acquisition that had not been previously reported. Our previous studies analyzed the differences in structural (Hernández et al, 2016(Hernández et al, , 2020 and FC during meditation state (Hernández et al, 2018) between those two samples. As such, the reported descriptive statistics on the participants are identical, while the resting-state fMRI dataset and analysis differences differ in terms of the analyzed MRI modality and respective phenomena.…”

“…Importantly, a common goal between SYM and these other meditation techniques is to keep the attention in the here and now at the present moment, detecting and correcting mind-wandering episodes. However, while some of these other meditation techniques have, as a key attentional focus, their own breathing , SYM is based on the spontaneous (Sahaja = spontaneous) awakening of the Kundalini energy (Coward, 1985), which meditators subjectively perceive as a cool breeze when they put their hands some centimeters above their head, which is associated with the achievement of yoga (yoga = union; Devi, 1997;Hendriks, 2018;Hernández et al, 2020). The "kundalini awakening" is suggested to allow the practitioners to perceive the state of their "subtle centers" called chakras that SYM practitioners mention that they perceive through "reflex points" that the chakras have in their hands (Devi, 1997;Morgan, 1999).…”