Amplitude Of Low-frequency Fluctuation And Functional Connectivity Analysis Based Resting-State Functional Magnetic Resonance Imaging Study In Bipolar ? Depression

Objective:To examine the characteristics of spontaneous activity of brain regions in patients with bipolar ? depression patients by using resting state functional magnetic resonance imaging technology,and to explore the pathologic mechanism of bipolar II depression.Methods:Twenty-one patients with bipolar depression patients(BD group)and 21 age-,sex-and education level-matched healthy controls(HC group)were recruited.Each participant underwent resting-state functional magnetic resonance imaging scanning.Intra-regional brain activity was evaluated by using anamplitude of low frequency fluctuation(ALFF)approach,and independent-samples t test was used to analyze the difference between BD group and HC groups.Correlation between the differences of ALFF of brain areas and the depression severity were further analyzed.The areas with significantly altered ALFF were further selected as seeds in subsequent functional connectivity(FC)analysis.The FC was compared between groups to explore the disturbed mood network in bipolar depression.Results:The ALFFs of left paracentral lobule(t = 3.80),right precuneus(t = 3.54)and right precentral gyrus(t = 3.66)in BD group were significantly higher than HC group(all p<0.05,GRF correction).In BD group,the ALFFs of the left orbital frontal gyrus(r =0.75)and right orbital frontal gyrus(r = 0.80)were positively correlated with the HAMA score.The ALFFs of bilateral gyri rectus(r = 0.73)and brain regions near the left insular lobe(r = 0.74)were positively correlated with the HAMD17 score.The ALFF of region 2 of right cerebellar peduncles(r = 0.65)was negatively correlated with the MADRS score(all p<0.05).The functional connectivity between paracentral lobule,precuneus,precentral gyrus and left middle frontal gyrus,left anterior cingulate gyrus together with its lateral gyrus in BD group was significantly increased relative to HC group(t = 4.47,4.07;p<0.05),while the functional connectivity between the right rectangular shape crack and the cortex around was decreased in BD group(t = 4.54,p<0.05).Conclusions:The present study suggested the patients with bipolar II depression have significantly different ALFF and FC in left paracentral lobule,right precuneus and right precentral gyrus with companion of healthy people.These nerual charactistics were correlated with the severity of clinical symptoms.