Interconnections and global transitions among functional states encode activity-related dynamics as brain topology changes after yoga training

Figures

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  Fig. 1. Spatial configuration of MSs and analysis of temporal parameters. (a) Topographic plots of the MSs. (i) Data from before yoga training show cluster maps of A, B, C & D, and (ii) data from after yoga training reveal cluster maps of B, C, D & E. Estimated GEV (b), occurrence (c), time coverage (d), and mean duration (e) from four MSs before and after yoga training. Maps B & D decreased in frequency after yoga training from 1.47 Hz (± 0.346) to 0.628 Hz (± 0.510) (p = 0.048). (Gray color indicates pre-yoga, and orange color indicates post-yoga). The decreased occurrence of MSs may suggest enhanced attention and focus after yoga training among subjects.

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  Fig. 2. Transition probabilities before (gray color) and after (orange color) yoga training (p values of 0.0332 (*), 0.0021 (**), 0.0002 (***)). The decreased probability of transition (from B →◊D t (13) = 2.98, p value = 0.011) was not significant (to 3% after yoga training). The transition may implicate changes in network activity from visual to salience network regions.

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  Fig. 3. Functional connectivity networks assessed before and after yoga training. (a) The temporal variability of microstate B decreased from 0.994 to 0.985, and that of microstates C & D decreased from 0.99 to 0.96. (b) The spatial variability for microstate classes B, C, & D did not indicate any major differences. The box plot left of each pair shows variability before yoga training, and the box plot on the right of each pair shows variability after yoga training (** indicates a significant difference with p < 0.05, *** indicates a significant difference with p < 0.001).

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  Fig. 4. Relative power spectral density before and after yoga training (a & b). Frequency domain power topography plots before and after yoga training averaged across all the participants. The power from 5 frequency bins (0–4;4–8; 8–13;13–30;30–45 Hz) before yoga training and after yoga training was averaged over 2 s. The activity distribution before and after yoga clearly differed in the frequency ranges of α, β and γ. (c) The relative percentage changes observed before and after yoga training decreased in the frontal regions at the α,β, and γ frequencies.

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  Fig. 5. Yoga training study design. The study design comprised a total duration of 22 min and 20 s and was divided into distinct phases. The initial phase consisted of prerecording (blue color) with the eyes closed, lasting 2 min and 40 s, which captured baseline measurements prior to yoga training. Following this, participants engaged in a 15-minute session of yoga training (green color), a series of 12 postures performed in a flowing sequence as in pictorial representation. After the training, there was a 2-minute break (gray color) to allow the participants to rest. Finally, a post-yoga recording (pink color) of 2 min and 40 s was conducted with the participants’ eyes closed. This process was repeated for all 39 trials (3 trials each on 13 subjects).

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  Fig. 6. Illustration of global field power and microstate analysis for yoga training data. (a) Noise-removed preprocessed data. (b) Estimated global field power (GFP) across brain topologies. (c) The peaks of the GFP are used for clustering via algorithms such as k-means, typically from n = 4 to n = 8. (d) Fitting the cluster maps to the original data. (e) Microstates segmented from a trial in an epoch for a period of 1 s (x-axis is time in seconds).