Interhemispheric disconnectivity in the sensorimotor network in bipolar disorder revealed by functional connectivity and diffusion tensor imaging analysis

Takuya Ishida; Tomohiro Donishi; Jun Iwatani; Shinichi Yamada; Shun Takahashi; Satoshi Ukai; Kazuhiro Shinosaki; Masaki Terada; Yoshiki Kaneoke

doi:10.1016/j.heliyon.2017.e00335

Interhemispheric disconnectivity in the sensorimotor network in bipolar disorder revealed by functional connectivity and diffusion tensor imaging analysis

Heliyon. 2017 Jun 23;3(6):e00335. doi: 10.1016/j.heliyon.2017.e00335. eCollection 2017 Jun.

Authors

Takuya Ishida^{1

2}, Tomohiro Donishi¹, Jun Iwatani², Shinichi Yamada², Shun Takahashi², Satoshi Ukai², Kazuhiro Shinosaki², Masaki Terada³, Yoshiki Kaneoke¹

Affiliations

¹ Department of System Neurophysiology, Graduate School of Wakayama Medical University, 811-1 Kimiidera, Wakayama 641-8509, Japan.
² Department of Neuropsychiatry, Graduate School of Wakayama Medical University, 811-1 Kimiidera, Wakayama 641-8509, Japan.
³ Wakayama-Minami Radiology Clinic, 870-2 Kimiidera, Wakayama 641-0012, Japan.

Abstract

Background: Little is known regarding interhemispheric functional connectivity (FC) abnormalities via the corpus callosum in subjects with bipolar disorder (BD), which might be a key pathophysiological basis of emotional processing alterations in BD.

Methods: We performed tract-based spatial statistics (TBSS) using diffusion tensor imaging (DTI) in 24 healthy control (HC) and 22 BD subjects. Next, we analyzed the neural networks with independent component analysis (ICA) in 32HC and 25 BD subjects using resting-state functional magnetic resonance imaging.

Results: In TBSS analysis, we found reduced fractional anisotropy (FA) in the corpus callosum of BD subjects. In ICA, functional within-connectivity was reduced in two clusters in the sensorimotor network (SMN) (right and left primary somatosensory areas) of BD subjects compared with HCs. FC between the two clusters and FA values in the corpus callosum of BD subjects was significantly correlated. Further, the functional within-connectivity was related to Young Mania Rating Scale (YMRS) total scores in the right premotor area in the SMN of BD subjects.

Limitations: Almost all of our BD subjects were taking several medications which could be a confounding factor.

Conclusions: Our findings suggest that interhemispheric FC dysfunction in the SMN is associated with the impaired nerve fibers in the corpus callosum, which could be one of pathophysiological bases of emotion processing dysregulation in BD patients.

Keywords: Medical imaging; Neuroscience; Psychiatry.