Cortical hierarchy disorganization in major depressive disorder and its association with suicidality.

Objectives: To explore the suicide risk-specific disruption of cortical hierarchy in major depressive disorder (MDD) patients with diverse suicide risks. Methods: Ninety-two MDD patients with diverse suicide risks and 38 matched controls underwent resting-state functional MRI. Connectome gradient analysis and stepwise functional connectivity (SFC) analysis were used to characterize the suicide risk-specific alterations of cortical hierarchy in MDD patients. Results: Relative to controls, patients with suicide attempts (SA) had a prominent compression from the sensorimotor system; patients with suicide ideations (SI) had a prominent compression from the higher-level systems; non-suicide patients had a compression from both the sensorimotor system and higher-level systems, although it was less prominent relative to SA and SI patients. SFC analysis further validated this depolarization phenomenon. Conclusion: This study revealed MDD patients had suicide risk-specific disruptions of cortical hierarchy, which advance our understanding of the neuromechanisms of suicidality in MDD patients.

Aberrant Inter-hemispheric Connectivity in Patients With Recurrent Major Depressive Disorder: A Multimodal MRI Study.

Objective: Inter-hemispheric network dysconnectivity has been well-documented in patients with recurrent major depressive disorder (MDD). However, it has remained unclear how structural networks between bilateral hemispheres relate to inter-hemispheric functional dysconnectivity and depression severity in MDD. Our study attempted to investigate the alterations in corpus callosum macrostructural and microstructural as well as inter-hemispheric homotopic functional connectivity (FC) in patients with recurrent MDD and to determine how these alterations are related with depressive severity. Materials and Methods: Resting-state functional MRI (fMRI), T1WI anatomical images and diffusion tensor MRI of the whole brain were performed in 140 MDD patients and 44 normal controls matched for age, sex, years of education. We analyzed the macrostructural and microstructural integrity as well as voxel-mirrored homotopic functional connectivity (VMHC) of corpus callosum (CC) and its five subregion. Two-sample t-test was used to investigate the differences between the two groups. Significant subregional metrics were correlated with depression severity by spearman's correlation analysis, respectively. Results: Compared with control subjects, MDD patients had significantly attenuated inter-hemispheric homotopic FC in the bilateral medial prefrontal cortex, and impaired anterior CC microstructural integrity (each comparison had a corrected P < 0.05), whereas CC macrostructural measurements remained stable. In addition, disruption of anterior CC microstructural integrity correlated with a reduction in FC in the bilateral medial prefrontal cortex, which correlated with depression severity in MDD patients. Furthermore, disruption of anterior CC integrity exerted an indirect influence on depression severity in MDD patients through an impairment of inter-hemispheric homotopic FC. Conclusion: These findings may help to advance our understanding of the neurobiological basis of depression by identifying region-specific interhemispheric dysconnectivity.

An aberrant hippocampal subregional network, rather than structure, characterizes major depressive disorder.

BACKGROUND: Behavioral and neuroimaging studies have implicated the hippocampus as a cardinal neural structure in major depressive disorder (MDD) pathogenesis. The hippocampal subregion-specific structural and functional abnormalities in MDD remain unknown. METHODS: Multimodal magnetic resonance imaging (MRI) was acquired in 140 patients with MDD and 44 age- and sex-matched healthy controls (HCs). We quantified hippocampal subregional volumes and fractional anisotropy (FA) following a structural and diffusion MRI data analysis processing stream. Hippocampal subregional networks were established using seed-based functional connectivity (FC) analysis. Univariate analysis was used to investigate the differences between the two groups. Significant subfield metrics were correlated with depression severity. RESULTS: Compared with HCs, we did not find significant differences in subregional volumes or FA metrics in the MDD group. The MDD group exhibited a significantly weaker connectivity of the right hippocampal subregional networks with the temporal cortex (extending to the insula) and basal ganglia but showed increased connectivity of the right subiculum to the bilateral lingual gyrus. The FC between the right cornu ammonis 1 and right fusiform, between the right hippocampal amygdala transition area and the bilateral basal ganglia, were negatively correlated with depression severity (r = -0.224, p = 0.010; r = -0.196, p = 0.025, respectively) in the MDD group. LIMITATIONS: This study did not consider the longitudinal changes in the structure and functional connectivity of the hippocampal subregion. CONCLUSION: These findings advance our understanding of the neurobiological basis of depression by identifying the hippocampal subregional structural and functional abnormalities.

Progressive network impairment in patients with chronic hepatitis B virus related cirrhosis: a combined resting-state functional MRI and diffusion tensor imaging study / 中华放射学杂志

Objective:To explore the disease-related impairment of functional and structural connectivity network and their relationship with psychometric hepatic encephalopathy score (PHES) in patients with chronic hepatitis B virus-related cirrhosis (HBV-RC) by combining resting-state functional MRI (rs-fMRI) and diffusion tensor imaging (DTI).Methods:Data of 30 HBV-RC patients [including 13 HBV-RC patients with minimal hepatic encephalopathy (MHE) and 17 HBV-RC patients without MHE (NMHE)] from April 2011 to October 2011 in Guangdong No.2 People′s Hospital were analyzed prospectively, and 38 healthy individuals matched for age, sex, and education with HBV-RC patients (HC group) were included during the same period. Rs-fMR and DTI data as well as PHES data of all participants were collected. Gretna and PANDA software package were used to preprocess the imaging data and construct the functional and structural network respectively. The network-based statistic (NBS) approach was used to compare the differences of the functional and structural connections among three groups. Spearman′s correlation analysis was used to identify the relationship between functional or structural connectivity and PHES. The structural equation modeling (SEM) was used to explore the relationships among functional connectivity, structural connectivity, and PHES.Results:Compared to HC group, both functional and structural connectivity in the whole brain progressively destroyed from NMHE to MHE, mainly involving cognitive control network, default mode network, and limbic network (NBS corrected, all P<0.01). There were significantly negative relationships between functional or structural connectivity and PHES in HBV-RC patients (false discovery rate corrected, all P<0.05). The SEM results showed the influence of structural connectivity on neurocognitive impairment was mediated by functional connectivity ( P<0.05). Conclusion:Both functional and structural networks progressively destroy in HBV-RC patients as the disease advanced and these alterations significantly correlate with PHES. Besides, the influence of structural connectivity on neurocognitive impairment is mediated by functional connectivity.

Resting-state fMRI fALFF analysis in patients with non-fluent aphasia after ischemic stroke / 实用医学杂志

Objective To understand the impairment and compensation mechanism of brain function in pa-tients with non-fluent aphasia after ischemic stroke. The fractional amplitude of low frequency fluctuation (fALFF) method was used to analyze the functional magnetic resonance imaging (fMRI) data in the resting state between the aphasia patients and the normal controls. Methods The scans of the resting state of fMRI were performed in 17 aphasia patients and 19 age-, education-, and sex-matched healthy control subjects. The scan sequence was single-shot echo planar image,DPARSF software was used to analyze fALFF data of the aphasia patients and the healthy controls. Results Compared to the control group, the value in right superior temporal gurus, inferior parietal lob-ule, frontal lobe cortex, and postcentral gurus were significantly increased in the aphasia group. The fALFF in bilat-eral cerebellum and right thalamus were also decreased in the aphasia group. Conclusions The fALFF values in some brain region in the aphasia group were abnormal in the resting state , indicating a few pathological change of brain function in patients with non-fluent aphasia after ischemic stroke.

The application of diffusion tensor imaging and diffusion tensor tractography in the perioperative assessment of tumors involving brainstem / 中华放射学杂志

Objective To explore the value of diffusion tensor imaging (DTI) and diffusion tensor tracography (DTT) in assessment of Corticospinal tract (CST) and medial lemniscus (ML) in tumors involving brainstem.Methods A total of 35 cases with pathologically confirmed tumors involving brainstem were collected,and 35 volunteers matched with genders and ages were recruited as the normal group.DTI scanning was performed on all the patients and controls.The damage degrees of CST and ML were evaluated and graded by DTT,and the dysfunction degrees were evaluated for the patients.Spearman correlation was used to statistically analyze the relationships of limb movement,sensory dysfunction and CST and ML damage.Results According to the rating results,normal findings,shifting,edema or infiltration and damage of CST was found in 9,9,11,and 6 cases respectively.They were 8,9,15,3 cases for ML.Motor function was normal in 20 cases,slightly defective in 11 cases,and moderate defective in 4 cases.Sensory function was normal in 21 cases,slightly defective in 6 cases,and moderate defective in 8 cases.The patients' dyskinesia and CST damage degree,sensory dysfunction and ML damage degree were positively correlated (r was 0.786 and 0.686 respectively,P ＜ 0.01).The position relationship among tumor and CST and ML could be well displayed on images.None of the patients showed new symptoms of dysneuria after surgery.Conclusions DTI and DTT technology can be used to evaluate CST and ML damage degree in tumors involving brainstem.They can display the position relationship between tumor and the brainstem CST and ML,which is important in protecting the brainstem fiber tract during operation and evaluating the recovery after the operation.

Alterations in orbitofrontal cortex functional connectivity and decision making deficits in heroin-dependent individuals / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the changes in orbitofrontal cortex (OFC) functional connectivity and its association with decision-making deficits in chronic heroin-dependent individuals (HDIs) and explore the neural mechanisms of heroin addiction and relapse.</p><p><b>METHODS</b>Fourteen male chronic HDIs and 14 healthy subjects matched for age, education, and nicotine consumption participated in this study. Resting state functional magnetic resonance imaging (fMRI) was performed using a 1.5 T MR scanner. Functional connectivity of the OFC and the rest of the brain were calculated using REST software. Voxel-based analysis of the functional connectivity maps between the control and HDI groups was performed with two-sample t test. The Iowa gambling task (IGT) was used to assess the participants' decision making during uncertainty.</p><p><b>RESULTS</b>Compared with the control group, the HDIs showed significantly decreased functional connectivity of the OFC and the right inferior parietal lobule (rIPL) (t=3.5, P<0.05). A significant negative correlation was noted between the functional connectivity of the OFC-rIPL and performance level at the IGT.</p><p><b>CONCLUSION</b>The OFC-rIPL functional connectivity is significantly disrupted in HDIs, which may be the neural basis for decision-making deficits.</p>