Large effects of brief meditation intervention on EEG spectra in meditation novices

Abstract

This study investigated the impact of a brief meditation workshop on a sample of 223 novice meditators. Participants attended a three-day workshop comprising daily guided seated meditation sessions using music without vocals that focused on various emotional states and intentions (open focus). Based on the theory of integrative consciousness, it was hypothesized that altered states of consciousness would be experienced by participants during the meditation intervention as assessed using electroencephalogram (EEG). Brainwave power bands patterns were measured throughout the meditation training workshop, producing a total of 5616 EEG scans. Changes in conscious states were analysed using pre-meditation and post-meditation session measures of delta through to gamma oscillations. Results suggested the meditation intervention had large varying effects on EEG spectra (up to 50 % increase and 24 % decrease), and the speed of change from pre-meditation to post-meditation state of the EEG co-spectra was significant (with 0.76 probability of entering end-meditation state within the first minute). There was a main 5 % decrease in delta power (95 % HDI = [-0.07, -0.03]); a global increase in theta power of 29 % (95 % HDI = [0.27, 0.33]); a global increase of 16 % (95 % HDI = [0.13, 0.19]) in alpha power; a main effect of condition, with global beta power increasing by 17 % (95 % HDI = [0.15, 0.19]); and an 11 % increase (95 % HDI = [0.08, 0.14]) in gamma power from pre-meditation to end-meditation. Findings provided preliminary support for brief meditation in altering states of consciousness in novice meditators. Future clinical examination of meditation was recommended as an intervention for mental health conditions particularly associated with hippocampal impairments.

Keywords: Brain waves; Electroencephalogram (EEG); Meditation; States of consciousness; Stress.

Fig. 1

Shows violin plots of posterior estimates for classifier accuracy by meditation technique, indicating invariance of accuracy across meditation techniques.

Fig. 2

Depicts violin plots of posterior estimates for classifier proficiency by meditation technique, indicating invariance of proficiency across meditation techniques.

Fig. 3

Shows a violin plot of the posterior estimates of logistic regression intercept of classification series for each meditation technique. The intercepts are quite large indicating changes in EEG co-spectra occurred quite quickly and the figure also depicts the invariance of intercept across techniques.

Fig. 4

Shows the median estimates for logistic regression of classification series for each meditation technique.

Fig. 5

Illustrates a violin plot of the posterior estimates for logistic regression slopes of classification series for each meditation technique. D2S2 has a larger slope than D3S2 indicating end-meditation EEG co-spectra was achieved more rapidly for D2S2.

Fig. 6

Depicts violin plots of the posterior estimates for percent change in Delta power for each meditation technique, and indicates a varied effect of technique, with groups showing increases (D1S2, D3S1, D4S1), invariance (D2S2) and decreases (D1S1, D1S3, D2S1, D2S3, D3S2) in power.

Fig. 7

Shows the overall median posterior estimate for proportion change in power band topographies.

Fig. 8

Consists of violin plots of the posterior estimates for percent change in Theta power for each meditation technique. The majority of techniques increased theta power.

Fig. 9

Shows violin plots of the posterior estimates for percent change in alpha power for each meditation technique. The majority of techniques increased alpha power.

Fig. 10

Depicts violin plots of the posterior estimates for percent change in beta power for each meditation technique. The majority of techniques increased beta power, while three techniques (D1S1, D1S3, D2S1) had no change in beta power.

Fig. 11

Shows violin plots of the posterior estimates for percent change in gamma power for each meditation technique. The majority of techniques increased gamma power, with two techniques showing no change in gamma power and one showing a decrease.

Fig. 12

Summarises the posterior estimates for percent change in power for each meditation technique and each power band. The pattern of power changes were quite varied for each technique.