The modulation of brain functional connectivity with manual acupuncture in healthy subjects: An electroencephalograph case study

Abstract

Manual acupuncture is widely used for pain relief and stress control. Previous studies on acupuncture have shown its modulatory effects on the functional connectivity associated with one or a few preselected brain regions. To investigate how manual acupuncture modulates the organization of functional networks at a whole-brain level, we acupuncture at ST36 of a right leg to obtain electroencephalograph (EEG) signals. By coherence estimation, we determine the synchronizations between all pairwise combinations of EEG channels in three acupuncture states. The resulting synchronization matrices are converted into functional networks by applying a threshold, and the clustering coefficients and path lengths are computed as a function of threshold. The results show that acupuncture can increase functional connections and synchronizations between different brain areas. For a wide range of thresholds, the clustering coefficient during acupuncture and post-acupuncture period is higher than that during the pre-acupuncture control period, whereas the characteristic path length is shorter. We provide further support for the presence of “small-world" network characteristics in functional networks by using acupuncture. These preliminary results highlight the beneficial modulations of functional connectivity by manual acupuncture, which could contribute to the understanding of the effects of acupuncture on the entire brain, as well as the neurophysiological mechanisms underlying acupuncture. Moreover, the proposed method may be a useful approach to the further investigation of the complexity of patterns of interrelations between EEG channels.

Ordinal Pattern Based Complexity Analysis for EEG Activity Evoked by Manual Acupuncture in Healthy Subjects

“…The central effects of acupuncture stimulus are different from the previous results by Rosted et al [2001] and Xu et al [1998], which showed there are no changes brought about by acupuncture in the EEG signals. The modulations of brain activities with MA provide further support for the previous hypothesis that the brain plays a key role in acupuncture research [Yi et al, 2013a;Bian et al, 2011;Hsu et al, 2011;Yi et al, 2013b;Luo et al, 2012;Yi et al, 2013c;Hui et al, 2000;Litscher & Cho, 2000]. Our results also highlight the notion that modulation of cortical electrical activities may be an important mechanism by which acupuncture exerts its complex multisystem effects [Bian et al, 2011;Yi et al, 2013b;Luo et al, 2012;Yi et al, 2013c;Hui et al, 2000;Litscher & Cho, 2000].…”

“…As EEG can simultaneously record multichannel neural electrical signals in different brain areas at the macroscopic level, it is especially valuable for exploring brain behaviors after short, surprising stimuli, such as MA. Thus, a number of researchers introduced it to investigate the effects of acupuncture stimulus on brain activity [Chen et al, 2006;Yi et al, 2013a;Bian et al, 2011;Muchtadi et al, 2009;Sakai et al, 2007;Tanaka et al, 2002;Hsu et al, 2011;Yi et al, 2013b;Luo et al, 2012;Yi et al, 2013c].…”

“…As an alternative to spectral analyses, the linear connectivity measures are applied to explore the functional interactions between brain regions by acupuncture stimulus. It has been observed that acupuncture can increase EEG coherences and functional connections between different brain areas [Yi et al, 2013c]. However, there are no consistent results and it is difficult to integrate these findings into a unified framework.…”

Action potential threshold of wide dynamic range neurons in rat spinal dorsal horn evoked by manual acupuncture at ST36

“…It is an important meridian on Stomach Meridians, and acupuncturing it manually has been shown to produce various beneficial therapeutic effects [2,[4][5][6], such as treating sleep disorders, handling dizziness and gastrointestinal diseases, controlling stress, keeping calm and sedative, and so on. Meanwhile, this acupoint has also been commonly selected in experiments to study the acupuncture effects on brain activity [2,4,[6][7][8][9][10][11][12][13][14][15][16][17].…”

“…Thus, it has also been widely used to investigate the acupuncture-induced effects. With this noninvasive recording technique, our group has shown that acupuncturing at ST36 manually could increase EEG complexity [12][13][14] and coherence [15,16], reduce EEG relative powers in alpha and beta bands [17], enhance functional connection of brain network [15] and contribute to the information exchange between different brain areas [16]. However, how acupuncture at ST36 acupoint induces these modulatory effects on brain activity is still unclear.…”