|Reference code: ||PT/FB/BL-2006-044.19|
|Location: ||Arquivo PCA - Pasta 19/2006|
|Brain electric activity in meditation: Extension of earlier work and hypothesis testing|
|Publication year: ||2010|
A major objective of our Bial grant concerned the exploration of conceivable commonalities and differences of brain electric states in different traditions of meditation.
Pursuing this goal, brain electric functional connectivity was studied in experienced meditators of five traditions (13 Tibetan Buddhists, 15 QiGong, 14 Sahaja Yoga, 14 Ananda Marga Yoga, 15 Soto Zen) during tradition-specific meditation (selfdissolution, QiGong, Samadhi, Satori) and during wakeful resting before ('rest1') and after ('rest2') meditation. EEG (19-56 electrodes) was computed (via sLORETA, current density
in 6239 voxels) into intracerebral waveshapes of 19 intracerebral regions (ROIs) that correspond to cortex underlying the 10/20 electrode positions. Functional connectivity was computed from scalp-recorded data as conventional coherence between 19 locations, and from sLORETA waveshapes as 'lagged coherence' between 19 ROI's; lagged coherence only measures connections with time delay; these are interpretable as true
functional connectivity. - For each meditator group, t-tests identified significant coherence differences between rest1 vs meditation and rest2 vs meditation in each of 8 EEG frequency bands (delta to gamma). There are 171 connections between 19 locations or ROIs. For each subject and frequency band, we counted the percentage of connections that reached significantly different coherence between rest1 vs meditation and rest2 vs meditation; from these two %values, mean% was computed, and averaged across all 8 bands, separately for each tradition.
In the 5 traditions, for scalp coherences, 1% to 4% of the connections were significant higher in meditation than rest, 6% to 36% lower; for intracerebral lagged coherence, 0% were higher, between 26% to 68% were lower. On average across the 5 traditions, scalp coherence decreased most strongly in alpha1&2 and beta 1&2, while intracerebral lagged coherence decreased most strongly in delta, theta, beta1&2. For the gamma frequency band alone, scalp coherences were higher between 1% to 13%, lower between 1% to 27%; intracerebral lagged coherences were higher in 0%, lower between 2% to 75% of cases.
In sum, all 5 traditions clearly showed more significant decreases than increases in scalp coherence, and only significant decreases, but no increases in intracerebral lagged coherence that avoids distorting volume conduction. Contrary to published reports of strongly increased gamma band coherence in meditation, our 5 traditions on average in scalp coherence increased significantly only 4% of the gamma band coherences while 9% decreased; intracerebral lagged coherence showed no increase at all, but decrease in 44% of the coherences.
|Accessibility: ||Document does not exist in file|
|Secondary author(s): |
|Tei, S., Faber, P., Kumano, H., Gianotti, L., Pascual-Marqui, R.|
|Document type: |
|Number of reproductions: |
|Lehmann, D., Tei, S., Faber, P., Kumano, H., Gianotti, L., & Pascual-Marqui, R. (2010). Brain electric activity in meditation: Extension of earlier work and hypothesis testing. In Aquém e além do cérebro. Behind and beyond the brain. Proceedings of the 8th Symposium of Fundação Bial (pp. 205-206). Porto: Fundação Bial.|
|Indexed document: ||No|
|Keywords: ||Meditation traditions / Electroencephalogram (EEG) / Lagged coherence / sLoreta / Functional connectivity|
Brain electric activity in meditation: Extension of earlier work and hypothesis testing