Functional connectivity and power spectral density analysis of EEG signals in trained practitioners of Bhramari pranayama

Abstract

Bhramari Pranayama, which belongs to the group of pranayama, is a calming breadth practice. In the present study, we aim to investigate the cortical dynamics associated with Bhramari pranayama. We evaluated the power spectral density and cross-spectral density matrices in thirty trained practitioners before, during, and after they performed Bhramari pranayama. A significant increase (p < 0.05) in overall theta (12.64 µV2/Hz and 17.51 µV2/Hz) and alpha spectral power (19.36 µV2/Hz and 26.11 µV2/Hz) in the right temporal region of the brain was found during and after the pranayama. Additionally, a significant increase (p < 0.05) in gamma spectral power in the right (1.99 µV2/Hz) and left temporal (1.66 µV2/Hz) and parietal (1.62 µV2/Hz) regions, was observed during and after the pranayama. The cross-spectral density significantly increases after performing the Bhramari pranayama compared to before the pranayama in the alpha band (p < 0.05). Subsequently, all-to-all functional connectivity between EEG channels in sensor space is presented using circular graphs. Further graph theory analysis is employed to assess the effects of Bhramari pranayama on functional brain networks. These findings reveal that the alpha band's functional network topology of Bhramari meditators is more integrated during and after the meditation. Also, the power spectral changes are more prominent in the temporal region of the brain due to the generation of humming sound. By measuring these changes, meditators can determine the effectiveness of their pranayama practice inducing relaxation. Therefore, these results are valuable for enhancing pranayama practice and help in understanding the cortical mechanisms underlying pranayama.