FMRI-based Resting-state Brain Connectivity In Post-traumatic Stress Disorder

Post-traumatic stress disorder(PTSD)is a psychiatric disorder that can develop after individuals who have experienced or witnessed severe traumatic events.Motor vehicle accidents(MVA)are common traumatic events,and approximately 25% to 33% rates of PTSD have been reported to be caused by MVA.PTSD is characterized by persistent reexperiencing of the traumatic events,avoidance of reminders of the traumatic events and hyperarousal.Although the symptoms of PTSD are readily identifiable,the exact pathophysiology of PTSD remains not fully elucidated.In recent years,the development of functional magnetic resonance imaging(fMRI)provides an effective way to explore the pathophysiology of PTSD.In this study,we used the functional connectivity analysis methods to explore the pathophysiology of PTSD through fMRI.The brain functional networks of PTSD patients were measured at both local and global connectivity levels,as well as by functional connectivity and effective connectivity analyses to detect the neuropathological and physiological mechanisms of PTSD patients.The main work of this paper includes the following four parts:1.We used a seed-based functional connectivity method to explore the abnormal functional connectivity in PTSD.According to the previous studies,we selected the bilateral three insular subregions as seeds,by means of Pearson correlation method to calculate the functional connectivity between ROIs and other voxels in the whole brain exploring abnormal functional connectivity of the insular subregions in PTSD patients.The selected insular subregions include ventral anterior insula,dorsal anterior insula and posterior insula.We found that PTSD patients showed reduced functional connectivity,compared to healthy controls(HCs),between left ventral anterior insula and the anterior cingulate cortex.The PTSD patients also exhibited decreased functional connectivity between the right posterior insula and left inferior parietal lobule and postcentral gyrus relative to HCs.Our findings suggest that the insular cortex plays a key role in PTSD and provide new insight to look into the basis of pathophysiology in PTSD.2.This study used independent component analysis(ICA)to investigate the restingstate intranetwork and internetwork functional connectivity abnormalities in PTSD at the ‘global' functional connectivity level.By means of ICA method,we selected eight brain networks,including auditory network(AN),and visual network(VN),sensorymotor network(SMN),anterior default mode network(aDMN),posterior default mode network(pDMN),salience network(SN)and bilateral central executive network.Compared with HCs,the PTSD patients exhibited significantly decreased network connectivity within the AN,SMN,aDMN,pDMN and SN.Furthermore,the PTSD patients exhibited increased internetwork connectivity between SN and pDMN.These findings aim to explore the pathophysiological basis of PTSD at the brain network level and we found that the abnormalities widely distributed on brain networks and selective changes of brain network FC were observed.3.In the current study,we utilized functional connectivity density(FCD)mapping,a novel ultrafast voxel-wise data-driven approach,to characterize aberrant short-range FCD and long-range FCD in PTSD.First,we calculated both short-and long-range FCD in PTSD patients and HCs by data-driven approach.Compared with HCs,PTSD patients showed significantly increased long-range FCD in the left dorsolateral prefrontal cortex(DLPFC),but no abnormal short-range FCD was found in PTSD.Furthermore,seedbased FC analysis of the left DLPFC showed increased connectivity in the left superior parietal lobule,bilateral superior occipital gyrus and cuneus in PTSD patients.These findings suggest that PTSD patients exhibit a disruption of intrinsic FC in the frontoparietal circuitry and fronto-occipital circuitry4.We used the effective connectivity and univariate recognition analysis to explore the pathophysiology underlying PTSD.We selected dorsal anterior cingulate cortex(ACC),rostral ACC and perigenual ACC as seeds.By employing Granger causality analysis,we aimed to investigate the abnormal effective connectivity of subregions of ACC in PTSD.Compared with HCs,PTSD patients exhibited significantly decreased effective connectivity from the right anterior insula and inferior frontal gyrus to the right rostral ACC as well as decreased effective connectivity from the left perigenual ACC to precuneus and right angular gyrus.Additionaly,significantly increased effective connectivity from the medial prefrontal cortex to the left dorsal ACC were also found in the PTSD patients relative to HCs.Then,by using the univariate recognition analysis,we found that the abnormal effective connectivity from right insula to right rostral ACC could classify PTSD patients from HCs with accuracy rate of 80%.Our findings may supply a novel way for understanding the neurophysiological mechanisms of PTSD.