RÉSUMÉ
Objective Transient brain function inhibition is a common symptom after mild brain injury,but some patients show persistent post-concussional syndrome (PCS).The aims of this study are to assess functional and causal connectivity of attention and default mode network using resting-state functional MR imaging (fMRI) to investigate the abnormal connectivity and its significance in PCS patients.Methods Resting-state fMRI data were collected from 23 PCS patients with attention disorders,admitted to our hospital from November 2015 to October 2016 and 21 age-,gender,and education-matched healthy controls recruited at the same period.The fMRI data were analyzed by group independent component analysis (ICA) toolbox to attention networks and default mode network (DMN).The components of the selected networks were compared in PCS and healthy controls to explore the changes of functional connectivity (FC).Granger causality analysis (GCA) was performed by taking the above significant brain areas as regions of interest (ROIs) to calculate bivariate coefficient of each pair of ROIs.Comparisons were performed to find the significant different causal connectivity of the two groups.Results In attention networks,the FC value of left frontal eye field (FEF),bilateral intraparietal sulcus (IPS),bilateral ventral prefrontal cortex (vPFC) and bilateral temporo-parietal junction (TPJ) was decreased.In DMN,the FC value of bilateral medial prefrontal cortex (mPFC) was reduced and bilateral precuneus (PCUN) was enhanced.Correlating GCA value,it was increased significantly from left FEF to left PCUN and IPS,while it was reduced from left PCUN and IPS to left FEF;and it was decreased from left IPS to left vPFC and increased from left TPJ to left PCUN.Conclusion The attention networks are restrained in resting state,which may influence the attention function in PCS patients;and the causal connection is altered in the above ROIs,and these changes may be related to inhibition of activation of default network to compensate for the loss of attention function by antagonistic effects in PCS patients.