Modulation of Spectral Power and Functional Connectivity in Human Brain by Acupuncture Stimulation

Abstract

Acupuncture, as an external stimulation, can produce clinical effects via the central nervous system. In order to investigate the modulatory efficacy of acupuncture on brain activity, multichannel EEG signals evoked by acupuncture at "Zusanli" acupoint were recorded from healthy humans in three states: pre-acupuncture, acupuncture, and post-acupuncture. Power spectral density is first used to analyze the EEG power change during acupuncture process. It is found that EEG power significantly increased in the delta and alpha bands under acupuncture and high power level remained in alpha band after acupuncture. Then, we calculated phase lag index to quantify the phase synchronization of pair-wise channels. In acupuncture state, delta and alpha bands exhibit significantly higher synchronization degree than pre-acupuncture state. Additionally, post-effect of acupuncture can be observed in alpha band as high synchronization degree remains in post-acupuncture state. Moreover, functional brain networks converted from synchronization matrix in each band are reconstructed. Acupuncture increases long-range connections between left and right hemispheres and changes the position of main nodes. Graph theory metrics are extracted to explore the change of functional connectivity in different states. The result shows the functional networks in delta and alpha bands are small world networks (SWN) and acupuncture improves the SWN efficiency of functional network.

Functional Integration and Segregation in Multiplex Brain Networks for Alzheimer's Disease

“…Relationships between these properties and the cognitive decline progression were also observed (Kabbara et al, 2018). In addition to the observations in static networks within frequency bands, recent studies have also revealed that the multilayer (cross-frequency) network analysis can provide additional information (i.e., hub) compared to single-layer (frequency-specific) networks (Guillon et al, 2017;Yu et al, 2017). However, most of these studies are focused on the global information processing (integration) but neglected the local information processing (segregation) across frequency bands.…”

“…This result is in line with a recent MEG study reporting the disruption of specific occipital hub regions in AD. During the progression of disease, the patients may exhibit decreased hub centrality or number of hubs (Yu et al, 2017). Alternatively, owing to the loss of original hubs, some non-hub areas may become relatively more important to maintain the information flow within or across frequency bands and even become new hubs.…”

“…For these reasons, graph theory can provide a promising framework to characterize the pathological processes in AD brain (Tijms et al, 2013;Cai et al, 2018). Recent functional network studies have reported that AD is associated with decreased nodal centrality in higher-order association areas and selective impairment of hippocampus and posterior hub areas (Crossley et al, 2014;Yu et al, 2017). At larger topological scales, the brain networks of AD patients showed increased randomness with a loss of small-world features as the disease progresses (Stam et al, 2007;Sanz-Arigita et al, 2010;Vecchio et al, 2016).…”

Acupuncture affects different ways for migraineurs of long- and short- courses on the efficiency of structural brain network

“…This increased global efficiency suggested that acupuncture affected differently on SC and LC. A past trial [10] demonstrated that acupuncture (Zu San Li acupoint stimulation) increased the efficiency of the small-world network of healthy humans. Comparing to that, we considered the increased efficiency of SC in our study could be interpreted that patients with a short course could only build an abnormal brain circuits incompletely (close to healthy human, far from chronic migraineurs).…”

“…The field of functional neuroimaging provided several conclusions. An electroencephalogram (EEG) study [10] demonstrated that acupuncture improved the efficiency of functional brain networks in delta and alpha bands and promoted the long-range connections of bilateral hemispheres on the healthy individuals. A transcranial magnetic stimulation (TMS) trial [11] suggested that single acupoint stimulation increased the motor cortical excitation and decreased its inhabitation for the healthy volunteers.…”