Reduced interhemispheric resting-state functional connectivity in unmedicated bipolar II disorder.
OBJECTIVE
Abnormalities in structural and functional brain connectivity have been increasingly reported in patients with bipolar disorder (BD) by recent neuroimaging studies. However, relatively little is known about the changes in functional interaction between the cerebral hemispheres in BD. The present study aimed to examine the interhemispheric functional connectivity of the whole brain in patients with BD II during resting state.


METHODS
Twenty-six patients with unmedicated BD II depression and 40 normal controls underwent the resting-state functional magnetic resonance imaging. The functional connectivity between any pair of symmetrical interhemispheric voxels (i.e., functional homotopy) was measured by voxel-mirrored homotopic connectivity (VMHC).


RESULTS
The patients with BD II showed lower VMHC than normal controls in the medial prefrontal cortex and inferior temporal gyrus. No regions of increased VMHC were detected in patients. There were no significant correlations between the VMHC values in these regions and clinical severity of BD symptoms.


CONCLUSIONS
These findings suggest substantial impairment of interhemispheric coordination in BD II.
Clinical Experimental Center, First Affiliated Hospital of Jinan University, Guangzhou, China.|Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou, China.
Y
Y
Wang
Department of Psychiatry, First Affiliated Hospital of Jinan University, Guangzhou, China.
S
S
Zhong
Department of Psychiatry, First Affiliated Hospital of Jinan University, Guangzhou, China.
Y
Y
Jia
Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou, China.
Z
Z
Zhou
Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou, China.
Q
Q
Zhou
Medical Imaging Center, First Affiliated Hospital of Jinan University, Guangzhou, China.
L
L
Huang
D000293:Adolescent; D000328:Adult; D001714:Bipolar Disorder / Q000503:physiopathology*; D001931:Brain Mapping / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D017397:Prefrontal Cortex / Q000503:physiopathology*; D055815:Young Adult
bipolar disorder; functional magnetic resonance imaging; medial prefrontal cortex; voxel-mirrored homotopic connectivity