Altered anterior‐posterior connectivity through the arcuate fasciculus in temporal lobe epilepsy

How the interactions between cortices through a specific white matter pathway change during cognitive processing in patients with epilepsy remains unclear. Here, we used surface‐based structural connectivity analysis to examine the change in structural connectivity with Broca's area/the right Broca's homologue in the lateral temporal and inferior parietal cortices through the arcuate fasciculus (AF) in 17 patients with left temporal lobe epilepsy (TLE) compared with 17 healthy controls. Then, we investigated its functional relevance to the changes in task‐related responses and task‐modulated functional connectivity with Broca's area/the right Broca's homologue during a semantic classification task of a single word. The structural connectivity through the AF pathway and task‐modulated functional connectivity with Broca's area decreased in the left midtemporal cortex. Furthermore, task‐related response decreased in the left mid temporal cortex that overlapped with the region showing a decrease in the structural connectivity. In contrast, the region showing an increase in the structural connectivity through the AF overlapped with the regions showing an increase in task‐modulated functional connectivity in the left inferior parietal cortex. These structural and functional changes in the overlapping regions were correlated. The results suggest that the change in the structural connectivity through the left frontal–temporal AF pathway underlies the altered functional networks between the frontal and temporal cortices during the language‐related processing in patients with left TLE. The left frontal–parietal AF pathway might be employed to connect anterior and posterior brain regions during language processing and compensate for the compromised left frontal–temporal AF pathway. Hum Brain Mapp 37:4425–4438, 2016. © 2016 Wiley Periodicals, Inc.     

Cortical signature of clock drawing performance in Alzheimer's disease and mild cognitive impairment

It is unclear whether clock drawing test (CDT) performance relies on a widely distributed cortical network, or whether this test predominantly taps into parietal cortex function. So far, associations between cortical integrity and CDT impairment in Alzheimer's disease (AD) and mild cognitive impairment (MCI) largely stem from cortical volume analyses. Given that volume is a product of thickness and surface area, investigation of the relationship between CDT and these two cortical measures might contribute to better understanding of this cognitive screening tool for AD. 38 patients with AD, 38 individuals with MCI and 31 healthy controls (HC) underwent CDT assessment and MRI at 3 Tesla. The surface-based analysis via Freesurfer enabled calculation of cortical thickness and surface area. CDT was scored according to the method proposed by Shulman and related to the two distinct cortical measurements. Higher CDT scores across the entire sample were associated with cortical thickness in bilateral temporal gyrus, the right supramarginal gyrus, and the bilateral parietal gyrus, respectively (p < 0.001 CWP corr.). Significant associations between CDT and cortical thickness reduction in the parietal lobe remained significant when analyses were restricted to AD individuals. There was no statistically significant association between CDT scores and surface area (p < 0.001 CWP corr.). In conclusion, CDT performance may be driven by cortical thickness alterations in regions previously identified as “AD vulnerable”, i.e. regions predominantly including temporal and parietal lobes. Our results suggest that cortical features of distinct evolutionary and genetic origin differently contribute to CDT performance.     

成年早期首发精神分裂症患者脑皮层形态学研究

目的 采用基于体素的形态学分析(VBM)和基于表面的形态学分析(SBA)相结合的分析方法,探讨成年早期首次发病精神分裂症患者脑皮层改变区域,并寻找与精神症状相关的皮层改变脑区.方法 依据入组标准,纳入成年早期首次发病精神分裂症患者25例,招募25名健康志愿者为对照组,进行全脑磁共振扫描,获取3D脑结构图像,通过VBM8计算脑皮层体积,通过FreeSurfer软件计算脑皮层厚度与表面积,分别比较患者组和正常对照组间的差异,并将有差异脑区的皮层与PANSS评分(总评分、阳性症状评分、阴性症状评分及一般病理评分)进行相关性分析.结果 患者组左侧额叶直回、中央前回、颞中回、顶上小叶及右侧额上回、颞中回、颞上回、海马旁回、楔叶皮层体积与正常对照组相比减少,差异有统计学意义(P＜0.05);患者组左半球中的舌叶、颞下回、额中回后部及右半球中的颞下回、中央旁小叶、纺锤体、额上回、额中回后部皮层厚度与正常对照组相比,差异有统计学意义(P＜0.05);患者组皮层表面积与正常对照组比较,差异无统计学意义.左半球中额中回后部皮层厚度与PANSS阴性评分、PANNS总评分呈负相关(P＜0.05);右半球中额上回皮层厚度与PANSS阴性评分呈负相关(P＜0.05).结论 成年早期首次发病精神分裂症患者存在多个脑区灰质体积及皮层厚度异常,且有部分脑区的皮层厚度与患者精神症状严重程度相关.     

Brain volume reduction predicts weight development in adolescent patients with anorexia nervosa

BackgroundAcute anorexia nervosa (AN) is associated with marked brain volume loss potentially leading to neuropsychological deficits. However, the mechanisms leading to this brain volume loss and its influencing factors are poorly understood and the clinical relevance of these brain alterations for the outcome of these AN-patients is yet unknown.MethodsBrain volumes of 56 female adolescent AN inpatients and 50 healthy controls (HCs) were measured using MRI scans. Multiple linear regression analyses were used to determine the impact of body weight at admission, prior weight loss, age of onset and illness duration on volume loss at admission and to analyse the association of brain volume reduction with body weight at a 1-year follow-up (N = 25).ResultsCortical and subcortical grey matter (GM) and cortical white matter (WM) but not cerebellar GM or WM were associated with low weight at admission. Amount of weight loss, age of onset and illness duration did not independently correlate with any volume changes. Prediction of age-adjusted standardized body mass index (BMI-SDS) at 1-year follow-up could be significantly improved from 34% of variance explained by age and BMI-SDS at admission to 47.5–53% after adding cortical WM, cerebellar GM or WM at time of admission.ConclusionWhereas cortical GM changes appear to be an unspecific reflection of current body weight (“state marker”), cortical WM and cerebellar volume losses seem to indicate a longer-term risk (trait or “scar” of the illness), which appear to be important for the prediction of weight rehabilitation and long-term outcome.     

运动神经元病患者大脑结构异常评估:基于多模态成像

目的探究性利用多模态影像技术评估14例运动神经元病(MND)患者脑部灰白质结构改变,分析疾病表征及脑内异常的相关性。方法14例临床诊断考虑为MND患者作为实验组,认知功能评分正常,14例年龄、性别和左右利手匹配的无神经系统疾病的志愿者为对照组,行常规磁共振扫描以及T13D和DTI扫描。应用Freesurfer软件对T13D数据进行分析,组间比较全脑皮层厚度差异。应用基于纤维束示踪的空间统计方法(TBSS)和基于白质模板分割法分析DTI数据,比较全脑白质结构差异。显著差异白质结构特征值与临床指标作相关性分析。结果与对照组相比,Freesurfer结果显示MND患者右侧颞上回和左侧额中回下部局部局限性皮层厚度减低(P<0.05,非FDR校正)。TBSS结果表明胼胝体至运动皮层区域皮质脊髓束FA值和F1值呈显著性降低(P<0.05,FEW校正),而相应区域F2、L1、MD等值未见明显差异,特别是左侧上放射冠白质纤维,其FA值显著性降低(P=0.007),并与ALSFRs评分正相关(r^2=0.723,P=0.004)。结论无明显认知障碍MND患者主要表现为轻微灰质结构改变,白质结构特别是胼胝体至运动皮层的皮质脊髓束纤维结构完整性损伤,运动功能皮层信息上下传导受阻。上放射冠FA值与疾病严重程度相关,未来可用于监测疾病严重程度和发展进程。     

Cortical surface mapping using topology correction, partial flattening and 3D shape context-based non-rigid registration for use in quantifying atrophy in Alzheimer's disease

Magnetic resonance (MR) provides a non-invasive way to investigate changes in the brain resulting from aging or neurodegenerative disorders such as Alzheimer's disease (AD). Performing accurate analysis for population studies is challenging because of the interindividual anatomical variability. A large set of tools is found to perform studies of brain anatomy and population analysis (FreeSurfer, SPM, FSL). In this paper we present a newly developed surface-based processing pipeline (MILXCTE) that allows accurate vertex-wise statistical comparisons of brain modifications, such as cortical thickness (CTE). The brain is first segmented into the three main tissues: white matter, gray matter and cerebrospinal fluid, after CTE is computed, a topology corrected mesh is generated. Partial inflation and non-rigid registration of cortical surfaces to a common space using shape context are then performed. Each of the steps was firstly validated using MR images from the OASIS database. We then applied the pipeline to a sample of individuals randomly selected from the AIBL study on AD and compared with FreeSurfer. For a population of 50 individuals we found correlation of cortical thickness in all the regions of the brain (average r = 0.62 left and r = 0.64 right hemispheres). We finally computed changes in atrophy in 32 AD patients and 81 healthy elderly individuals. Significant differences were found in regions known to be affected in AD. We demonstrated the validity of the method for use in clinical studies which provides an alternative to well established techniques to compare different imaging biomarkers for the study of neurodegenerative diseases.