Brain functional connectivity network studies of acupuncture: a systematic review on resting-state fMRI

doi:10.1016/j.joim.2017.12.002

Journal of Integrative Medicine

Volume 16, Issue 1, January 2018, Pages 26-33

https://doi.org/10.1016/j.joim.2017.12.002 Get rights and content

Abstract

Background

Functional magnetic resonance imaging (fMRI) is a novel method for studying the changes of brain networks due to acupuncture treatment. In recent years, more and more studies have focused on the brain functional connectivity network of acupuncture stimulation.

Objective

To offer an overview of the different influences of acupuncture on the brain functional connectivity network from studies using resting-state fMRI.

Search strategy

The authors performed a systematic search according to PRISMA guidelines. The database PubMed was searched from January 1, 2006 to December 31, 2016 with restriction to human studies in English language.

Inclusion criteria

Electronic searches were conducted in PubMed using the keywords “acupuncture” and “neuroimaging” or “resting-state fMRI” or “functional connectivity”.

Data extraction and analysis

Selection of included articles, data extraction and methodological quality assessments were respectively conducted by two review authors.

Results

Forty-four resting-state fMRI studies were included in this systematic review according to inclusion criteria. Thirteen studies applied manual acupuncture vs. sham, four studies applied electro-acupuncture vs. sham, two studies also compared transcutaneous electrical acupoint stimulation vs. sham, and nine applied sham acupoint as control. Nineteen studies with a total number of 574 healthy subjects selected to perform fMRI only considered healthy adult volunteers. The brain functional connectivity of the patients had varying degrees of change. Compared with sham acupuncture, verum acupuncture could increase default mode network and sensorimotor network connectivity with pain-, affective- and memory-related brain areas. It has significantly greater connectivity of genuine acupuncture between the periaqueductal gray, anterior cingulate cortex, left posterior cingulate cortex, right anterior insula, limbic/paralimbic and precuneus compared with sham acupuncture. Some research had also shown that acupuncture could adjust the limbic-paralimbic-neocortical network, brainstem, cerebellum, subcortical and hippocampus brain areas.

Conclusion

It can be presumed that the functional connectivity network is closely related to the mechanism of acupuncture, and central integration plays a critical role in the acupuncture mechanism.

Introduction

Acupuncture has been used as a traditional medicine in China for over 2000 years [1], and is now rapidly gaining popularity in Western alternative and complementary medicine practice for its undeniable therapeutic effects [2]. Exploring the mechanism of acupuncture has been a hot topic in the research of alternative and complementary medicine.

Since the 1970s, many studies in animal models have shown that the integration of the central nervous system is involved in the effect of acupuncture [3]. In the last 20 years, extensive functional magnetic resonance imaging (fMRI) research has focused on the study of the neurophysiological mechanism of acupuncture. Using neuroimaging technologies, researchers have been able to examine the acupuncture process in the brain noninvasively [4]. fMRI is a new method to quantify how acupuncture affects changes in the brain network [5], [6], [7], [8]. Many resting-state fMRI (rs-fMRI) studies have indicated that acupuncture regulates the activity of some cortical and subcortical brain regions [9], [10], [11].

This review presents a summary of current studies about brain functional connectivity networks in acupuncture research. The authors discussed aspects of study participants, acupoints, acupuncture methods, research methodology and their associated challenges. For this purpose, the study outcomes are discussed in several subgroups. The results provide an overview of changes in functional connectivity networks stimulated by different acupuncture acupoints or methods.

Section snippets

Literature search

The authors adopted a systematic search strategy according to the PRISMA guidelines [12]. Electronic searches were performed in PubMed using the keywords “acupuncture” and “neuroimaging” or “resting-state fMRI” or “functional connectivity”. Then the articles were screened by title and abstract. The PubMed database was initially searched from January 1, 2006 to December 31, 2016 with restriction to human studies in English language.

Eligibility criteria

Original studies of acupuncture on the brain functional

Study inclusion

A literature search was conducted, including publications from 2006 to 2016. Our search terms retrieved 136 records. After screening the title and abstract, the number was reduced to 83 articles. A further 39 articles were excluded when the full text failed to meet the inclusion criteria, leaving 44 articles for use in this study (Fig. 1). The publication year of all articles is shown in Fig. 2.

Result tables

A comparison of all included studies with regard to acupoints used, control intervention, number of

Discussion

Neuroimaging, as an effective means to explore the central mechanism of acupuncture’s effects, is widely used in acupuncture research. In recent years, instead of focusing on the changes in a single brain area during acupuncture, the researchers have focused more on the relationships among brain areas. The development of medical imaging has provided a good technical platform for the study of acupuncture mechanism. Brain connection is one of the most popular concepts in neuroscience at present,

Conclusion

This review provides an overview of 44 neuroimaging studies, including trials with healthy subjects, and patients with nervous system diseases, motor system diseases and other diseases. The results of this review show that acupuncture could increase DMN, SMN connectivity with pain-, affective- and memory-related brain areas. Verum acupuncture showed significantly greater connectivity between the PAG, ACC, left PCC, insula, limbic/paralimbic and precuneus compared with sham acupuncture. Some

Funding

This article was supported by the National Natural Science Foundation of China (No. 81473784), University Science Research Project of Anhui Province of China (No. KJ2017A298), the Key Project of the Youth Elite Support Plan in Universities of Anhui Province of China (No. gxyqZD2016134), Construction Project of Scientific Research Innovation Platform of Anhui Province of China (No. 2015TD033).

Conflict of interest

The authors declare that there is no conflict of interest regarding the publication of this paper.

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View full text

Systematic ReviewBrain functional connectivity network studies of acupuncture: a systematic review on resting-state fMRI

Abstract

Background

Objective

Search strategy

Inclusion criteria

Data extraction and analysis

Results

Conclusion

Introduction

Section snippets

Literature search

Eligibility criteria

Study inclusion

Result tables

Discussion

Conclusion

Funding

Conflict of interest

Pain

Pain

Neuroimage

Int J Surg

Magn Reson Imaging

Pain

Brain Res

Brain Res

Complement Ther Med

Magn Reson Imaging

Neuroimage Clin

Mol Pain

Neuroimage Clin

Neuroimage

Celestial lancets: a history and rationale of acupuncture and moxa

The developmental status and prospect of the science of acupuncture and moxibustion abroad

Zhongguo Zhen Jiu

FMRI study of acupuncture-induced periaqueductal gray activity in humans

Neuroreport

Neuroimaging and neuromonitoring effects of electro and manual acupuncture on the central nervous system: a literature review and analysis

Evid Based Complement Alternat Med

Connectomics: a new direction in research to understand the mechanism of acupuncture

Evid Based Complement Alternat Med

Opportunities and limitations of intrinsic functional connectivity MRI

Nat Neurosci

Consistency of network modules in resting-state fMRI connectome data

PLoS One

Clustering of resting state networks

PLoS One

FMRI connectivity analysis of acupuncture effects on an amygdala-associated brain network

Mol Pain

Combining spatial and temporal information to explore function-guide action of acupuncture using fMRI

J Magn Reson Imaging

Monitoring acupuncture effects on human brain by fMRI

J Vis Exp

Imaging the functional connectivity of the periaqueductal gray during genuine and sham electroacupuncture treatment

Mol Pain

Divergent neural processes specific to the acute and sustained phases of verum and sham acupuncture

J Magn Reson Imaging

The limbic-prefrontal network modulated by electroacupuncture at CV4 and CV12

Evid Based Complement Alternat Med

Systematic Review
Brain functional connectivity network studies of acupuncture: a systematic review on resting-state fMRI