| Objective The hippocampus is a key structure of the medial temporal lobe,which is thought to be involved in spatial encoding,navigation and episodic memory maintenance of working memory.At the same time,the anterior and posterior hippocampus have their own unique anatomical basis and functional selection.Studies have shown that the anterior hippocampus and amygdala are related to emotion regulation and fear,while the hippocampus tail is related to cognition.The posterior hippocampus is also involved in visuospatial information processing,working memory and spatial navigation.right temporal lobe epilepsy(r TLE)is known to have visuo-spatial working memory(VSWM)disorder,which is closely related to functional connectivity of the right frontal parietal network.As important subcortical brain regions of memory function,hippocampus and tail play an important role in spatial memory processing.However,it is not completely clear how changes in brain function and network connectivity between different hippocampal subareas and before and after r TLE patients affect VSWM defects.This study aims to explore and analyze the functional connections between the posterior hippocampus subregion and the whole cortex,and the functional connections between the anterior and posterior hippocampus and large-scale brain networks in r TLE patients at rest.To clarify the relationship between VSWM and the function and network connectivity abnormalities of different parts and subregions of hippocampus,and to provide evidence for elucidate the brain function and network mechanism of r TLE subregion related VSWM disorders.Method A total of 44 r TLE patients were enrolled in the outpatient department from 2019 to 2021,and 40 healthy controls matched in age,sex and education level were selected.All subjects underwent VSWM＿Nback behavioral test,and resting f MRI imaging and high-resolution 3DT1 structural image were collected.Automatic segmentation of the right hippocampus was performed by Free Surfer＿v7.1.0,and the differences of the posterior hippocampal subregion(Sub,CA1,CA3,CA4/DG,HPtail)and the Surface-based functional connectivity(SBFC)of the entorhinal cortex were compared between r TLE group and HC group.At the same time,the anterior and posterior hippocampus was the region of interest(ROI).Cortical regions closely related to VSWM function and the important cortical hypothalamus subregion were selected to construct VSWM-related brain functional networks,and FC differences within and between networks were analyzed and compared.Finally,abnormal SBFC and the key WM-related brain network FC were extracted from the hippocampal subfields of r TLE patients,and the correlation analysis between abnormal functional connectivity and network connectivity and behavioral performance was further conducted.Results 1.The VSWM＿2back score of r TLE patients was significantly lower than HC,FAR2 back increased and ACCmean RT prolonged.2.Functional connectivity(FC)analysis showed that SBFC of right hippocampus CA3,bilateral dorsolateral prefrontal lobe(DLPFC),right inferior parietal lobule(r IPC),right lateral temporal lobe(r LTC)and right occipital pole decreased significantly in r TLE patients,and most of these brain regions overlapped with the default network core subsystem(DMN-core)subsystem.The SBFC of right entorhinal cortex(r EC)and right anterior cingulate gyrus(r ACC)were increased.Correlation analysis showed that the decrease of SBFC in r CA3-r IPC and r CA3-r LTC was associated with poor VSWM performance in r TLE patients,and the increase of SBFC in r EC and r ACC was associated with the retention of VSWM performance.3.The functional connectivity in r TLE group were significantly higher than HC group.The increased FC were mainly located between VN and DAN,SVN,CONa,CONc,DMN-mtl,as well as between DMN and SVN,CONa,CONc,DAN,additionally between hippocampus and SVN,DAN.The decreased FC in r TLE group compared with HC group were mainly located within SVN,DMN-dmpfc,CONa and CONB-R networks,and between DAN and SVN,CONa,and between bilateral hippocampus and DMN-core and DMN-mtl.Correlation analysis showed that the increased HFC of right posterior hippocampus(p HPr)and DMN-core was significantly correlated with longer ACCmean RT2back;the increased HFC of left posterior hippocampus(p HPl)and Salience/Ventral-attention Network(SVN)was significantly correlated with longer ACCmean RT2 back.The increase of CONa and DMN-core HFC was significantly correlated with the increase of FAR2 back.Conclusion 1.The Reduced SBFC between r CA3 and r IPC may be a critical pattern of abnormal functional connectivity of VSWM deficit in r TLE patients,and the important brain mechanism may involve dysfunction of functional connectivity between DMN-mtl and DMN-core subsystems.2.The decreased functional connectivity between the p HPr and the DMN-core subsystem in r TLE patients is the critical abnormal functional connectivity leading to VSWM deficit.3.The higher network connection between CONa and DMN-core and between p HPl and SVN is an important abnormal network connection that leads to the VSWM deficit in r TLE patients.The mechanism may be related to the dysfunction of central execution and episodic buffer in WM process due to the difficulty of network dissociation. |
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