The Research Of Resting-state FMRI In Posttraumatic Stress Disorder

Part One.Aberrant regional homogeneity in posttraumatic stress disorder after traffic accident:a resting-state functional MRI studyObjectives:The present study explored the changes in spontaneous regional activity in post-traumatic stress disorder(PTSD)patients,who experienced severe traffic accidents.Methods:20 drug-naive PTSD patients and 18 healthy control subjects were imaged using resting-state functional magnetic resonance imaging(rs-fMRI)and analyzed by the algorithm of regional homogeneity(ReHo).Results:Compared to the healthy control group,the PTSD group showed decreased ReHo values in the right angular gyrus.In addition,a negative correlation was found between the activity level of the angular gyrus and the CAPS score.Conclusion:The dysfunctions were found in the memory-and emotion-related areas,suggested a possible mechanism of memory dysregulation that might be related to the intrusive memory symptoms of PTSD.These results provided imaging evidence that might provide an in-depth understanding of the intrinsic functional architecture of PTSD.Part Two.Altered local and large-scale dynamic functional connectivity variability in posttraumatic stress disorder:a resting state fMRI studyObjectives:Posttraumatic stress disorder(PTSD)is a psychiatric condition that can emerge after exposure to an exceedingly traumatic event.Previous neuroimaging studies have indicated that PTSD is characterized by aberrant resting-state functional connectivity(FC).However,few existing studies on PTSD have examined dynamic the changes in resting-state FC related to network formation,interaction and dissolution over time.In this study,we compared the dynamic resting-state local and large-scale FC between PTSD patients and healthy controls(HC).Method and materials:we compared the dynamic resting-state local and large-scale FC between PTSD patients(n=22)and healthy controls(HC)(n=22).Local dynamic FC was examined by calculating the dynamic regional homogeneity(dReHo),and large-scale dynamic FC(dFC)was investigated between regions with significant dReHo group differences.For the PTSD patients,we also investigated the relationship between symptom severity and dFC/dReHo.Results:Our results showed that PTSD patients were characterized by(?)increased dynamic(more variable)dReHo in left Precuneus(PCu);(?)increased dynamic(more variable)dFC between the left PCu and left insula;(?)decreased dFC between left PCu and left inferior parietal lobe(IPL),and decreased dFC between left PCu and right PCu.However,there is no significant correlation between the clinical indicators and dReHo/dFC after the family-wise-error(FWE)correction.Conclusion:These findings provided the initial evidence that PTSD is characterized by aberrant patterns of fluctuating communication within brain system such as the default mode network(DMN)and among different brain systems such as the salience network and the DMN.Part Three.The dynamic causal modeling study of default mode network in posttraumatic stress disorderObjectives:Previous studies of post-traumatic stress disorder(PTSD)found that patients had abnormalities in the default network.However,the existing research rarely mentions the difference between the effective connection in the default network of PTSD patients and normal people.This study intends to use the default network as a model for dynamic causal modeling(DCM)to explore the abnormal effective connectivity of DMN in PTSD patients.Method and materials:This study recruited 18 PTSD patients without any form of treatment and 18 normal subjects matched by gender,age,and education level as the research object,using resting state magnetic resonance imaging technology and using the spectrum DCM method to estimate the two groups.The parameters of the effective connection in the DMN of the subjects,and compare the difference of the effective connection in the DMN between the two groups.Results:The results show that there is a significant difference between the effective connection within the default network of PTSD patients and the normal people,with the change of the LIPC being the most obvious,LIPC receiving more information from mPFC and PCC,and PCC does not seem to widely accept the information of other nodes in the DMN network.Conclusion:Based on the results obtained,we found that there was an abnormal effective connection in DMN in PTSD patients,the mechanism that led to this effective connection was not clear,but the mechanism of this abnormal effective connection may be related to the patient's invasive memory,and mood regulation.