Chanting Amitofo increases slow­wave brain activities: an EEG component cluster analysis

Abstract

Introduction: Chanting and praying are some of the most common religious practices across the world. When chanting repetitively, the individuals’ mental state may change correspondingly. The frequency of EEG and brain rhythmic activities reflect the state of the neuronal network and its change may denote a state transition (Nguyen, Barbieri et al. 2008). Component cluster analysis may be able to extract the source of electroencephalogram (EEG) (Wyczesany, Grzybowski et al. 2015) and explore the neural correlates of religious chanting. In this experiment, we will explore the neural correlates of chanting Amitofo Buddha, which is one of the most popular forms of chanting in the Buddhist religion. It is often assumed that chanting Amitofo can induce a positive and peaceful mind state. Methods: Twenty one Buddhist participants with at least one-year chanting Amitofo experience were recruited. They were asked to chant 10 minutes silently of either Amitofo or Santa Claus (randomized sequence). A 128-channel EEG system was used to record these closed-eye EEG data. Independent component analysis (ICA) in EEGLab (https://sccn.ucsd.edu/eeglab/) was applied to categorize the ICA components of all the 42 data sets (21 participants x 2 chanting conditions). Eight clusters were generated by component clustering in EEGLab. A specific cluster of interest was selected to compare the ICA components in the two conditions. Position of the cluster was selected based on our pilot functional MRI study on chanting Amitofo, which found decreased computational centrality in precuneus area using eigenvector centrality mapping (see Figure 1). Thus we selected regions nearby for cluster analysis. Results: The slow-wave bands, delta and theta wave have significantly increased power in the left occipital brain region (see Figure 2). The power for delta wave (1-4Hz) during chanting Amitofo was significantly higher than that during chanting Santa Claus, their means were 37.21± 5.18 dB (Mean ± SD) and 32.69± 8.15 dB respectively, p = 0.011. The power for theta wave (4-8Hz) during chanting Amitofo was also higher than that during chanting Santa Claus, their means were 36.38 ±4.76 dB and 32.61 ±6.98 dB respectively, p = 0.04. The power analysis on other bands (alpha (8-12Hz), beta (12-30Hz), gamma (30-45Hz)) were not significant. Conclusions: The cluster analysis on EEG resting data showed that chanting Amitofo induced more slow-wave brain activities in the right posterior regions. Delta waves usually originate in thalamus or suprachiasmatic nuclei. It associates with the feeling of loving kindness (Faber 2016). Transcendent meditation also increases delta wave in the right temporal lobe (Cahn and Polich 2006). This preliminary study implies that repetitive religious chanting as external rhythms may entrain the endogenous neural oscillation in the low frequency band. One limitation is that more validation on component clustering of EEGLab might be required. Better localization methods of religious chanting could be explored in future studies. References Cahn, B. R. and J. Polich (2006). 'Meditation states and traits: EEG, ERP, and neuroimaging studies.' Psychological Bulletin 132(2): 180-211. Faber, E. S. L. (2016). 'The neural correlates of two forms of spiritual love: an EEG study.' bioRxiv beta: 1-23. Nguyen, D., R. Barbieri, M. Wilson and E. Brown (2008). Instantaneous frequency and amplitude modulation of EEG in the hippocampus reveals state dependent temporal structure. Conf Proc IEEE Eng Med Biol Soc: 1711-1715. Wyczesany, M., S. J. Grzybowski and J. Kaiser (2015). 'Emotional Reactivity to Visual Content as Revealed by ERP Component Clustering.' Journal of Psychophysiology 29(4): 135-146.