Dynamic Functional Connectivity Within the Fronto-Limbic Network Induced by Intermittent Theta-Burst Stimulation: A Pilot Study

Yingying Tang; Xiong Jiao; Junjie Wang; Tianyuan Zhu; Jie Zhou; Zhenying Qian; Tianhong Zhang; Huiru Cui; Hui Li; Xiaochen Tang; Lihua Xu; Ling Zhang; Yanyan Wei; Jianhua Sheng; Liu Liu; Jijun Wang

doi:10.3389/fnins.2019.00944

Dynamic Functional Connectivity Within the Fronto-Limbic Network Induced by Intermittent Theta-Burst Stimulation: A Pilot Study

Front Neurosci. 2019 Sep 13:13:944. doi: 10.3389/fnins.2019.00944. eCollection 2019.

Authors

Yingying Tang^{1

2}, Xiong Jiao^{1

3}, Junjie Wang^{1

4}, Tianyuan Zhu¹, Jie Zhou^{1

3}, Zhenying Qian¹, Tianhong Zhang¹, Huiru Cui¹, Hui Li¹, Xiaochen Tang¹, Lihua Xu¹, Ling Zhang⁴, Yanyan Wei¹, Jianhua Sheng¹, Liu Liu⁵, Jijun Wang^{1

6

7}

Affiliations

¹ Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
² Key Laboratory of Embedded System and Service Computing, Ministry of Education, Tongji University, Shanghai, China.
³ School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.
⁴ Institute of Mental Health, Suzhou Guangji Hospital, The Affiliated Guangji Hospital of Soochow University, Suzhou, China.
⁵ Department of Nuclear Medicine, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China.
⁶ CAS Center for Excellence in Brain Science and Intelligence Technology (CEBSIT), Chinese Academy of Sciences, Shanghai, China.
⁷ Institute of Psychology and Behavioral Science, Shanghai Jiao Tong University, Shanghai, China.

Abstract

Purpose: The utility of transcranial magnetic stimulation (TMS) has been growing rapidly in both neurocognitive studies and clinical applications in decades. However, it remains unclear how the responses of the stimulated site and the site-related functional network to the external TMS manipulation dynamically change over time.

Methods: A multi-session combining TMS-fMRI experiment was conducted to explore the spatiotemporal effects of TMS within the fronto-limbic network. Ten healthy volunteers were modulated by intermittent theta-burst stimulation (iTBS) at a precise site within the left dorsolateral prefrontal cortex (DLPFC, MNI coordinate [-44 36 20]), navigated by individual structural MRI image. Three-session resting-state fMRI images were acquired before iTBS (TP1), immediately after iTBS (TP2), and 15 min after iTBS (TP3) for each participant. Seventy-four regions of interests (ROIs) within the fronto-limbic network were chosen including the bilateral superior frontal gyrus (SFG), middle frontal gyrus (MidFG), inferior frontal gyrus (IFG), orbital gyrus (OrG), cingulate gyrus (CG), and subcortical nuclei (hippocampus and amygdala). Regional fractional amplitude of low-frequency fluctuation (fALFF) and ROI-to-ROI functional connectivity (FC) were compared among TP1, TP2, and TP3.

Results: The immediate iTBS effect was observed at the stimulated site. FC between the left dorsolateral SFG and left dorsal IFG and between the left rostral IFG and right MidFG increased at TP2 as compared to at TP1 (all FDR-p < 0.05), while FC within the left OrG decreased. The relatively long-term iTBS effect transmitted with decreased FC between the left IFG and right amygdala, increased FC between the left MidFG and left OrG, and decreased FC between bilateral IFG and OrG at TP3 than at TP1 (all FDR-p < 0.05). Meanwhile, mean fALFF values over the left SFG, MidFG, ventral CG, and IFG were significantly increased at TP3 as compared to those at TP2 (all p < 0.05 with Bonferroni correction).

Conclusion: By combining TMS and fMRI, it becomes possible to track the spatiotemporal dynamics of TMS after-effects within the fronto-limbic network. Our findings suggested that the iTBS effect dynamically changed over time from the local neural activation at the stimulated site to its connected remote regions within the fronto-limbic network.

Keywords: after-effects; functional connectivity; intermittent theta-burst stimulation; the fronto-limbic network; transcranial magnetic stimulation.