ICa

ICA
  • 文章类型: Journal Article
    患有抗N-甲基-D-天冬氨酸受体(抗NMDAR)脑炎的患者通常会出现严重的症状。静息状态功能MRI(rs-fMRI)揭示了患者功能网络的广泛损害。然而,信息流的变化仍不清楚。本研究旨在研究静息态网络(RSN)内部和之间的内在功能连通性(FC),以及这些网络之间有效连接(EC)的变化。
    静息状态功能磁共振成像(rs-fMRI)数据来自25例抗NMDAR脑炎患者和30例年龄匹配的健康对照(HCs),性别,和教育水平。使用独立成分分析(ICA)分析了RSN内部和之间的固有功能连接(FC)的变化。通过格兰杰因果关系分析(GCA)鉴定了RSN之间的功能相互作用。
    与HC相比,抗NMDAR脑炎患者在威斯康星卡片分类测试(WCST)中表现较低,无论是正确的数字还是正确的类别。此外,这些患者的蒙特利尔认知评估(MoCA)评分降低.神经影像学研究显示,默认模式网络(DMN)内的FC内异常,视觉网络(VN)和背侧注意力网络(DAN)内的FC内增加,以及VN和额叶网络(FPN)之间增加的FC间。此外,在DMN中观察到异常有效连接(EC),丹,FPN,VN,和躯体运动网络(SMN)。
    抗NMDAR脑炎患者表现出明显的记忆和执行功能缺陷。值得注意的是,这些患者在FC内表现出广泛的损伤,FC间,和EC。这些结果可能有助于解释抗NMDAR脑炎的病理生理机制。
    UNASSIGNED: Patients with anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis often experience severe symptoms. Resting-state functional MRI (rs-fMRI) has revealed widespread impairment of functional networks in patients. However, the changes in information flow remain unclear. This study aims to investigate the intrinsic functional connectivity (FC) both within and between resting-state networks (RSNs), as well as the alterations in effective connectivity (EC) between these networks.
    UNASSIGNED: Resting-state functional MRI (rs-fMRI) data were collected from 25 patients with anti-NMDAR encephalitis and 30 healthy controls (HCs) matched for age, sex, and educational level. Changes in the intrinsic functional connectivity (FC) within and between RSNs were analyzed using independent component analysis (ICA). The functional interaction between RSNs was identified by granger causality analysis (GCA).
    UNASSIGNED: Compared to HCs, patients with anti-NMDAR encephalitis exhibited lower performance on the Wisconsin Card Sorting Test (WCST), both in terms of correct numbers and correct categories. Additionally, these patients demonstrated decreased scores on the Montreal Cognitive Assessment (MoCA). Neuroimaging studies revealed abnormal intra-FC within the default mode network (DMN), increased intra-FC within the visual network (VN) and dorsal attention network (DAN), as well as increased inter-FC between VN and the frontoparietal network (FPN). Furthermore, aberrant effective connectivity (EC) was observed among the DMN, DAN, FPN, VN, and somatomotor network (SMN).
    UNASSIGNED: Patients with anti-NMDAR encephalitis displayed noticeable deficits in both memory and executive function. Notably, these patients exhibited widespread impairments in intra-FC, inter-FC, and EC. These results may help to explain the pathophysiological mechanism of anti-NMDAR encephalitis.
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  • 文章类型: Journal Article
    我们旨在使用功能磁共振成像(fMRI)评估麦角酰二乙胺(LSD)对健康受试者疼痛神经网络(PNN)的影响。
    20名健康志愿者参加了一项平衡顺序交叉研究,在两次fMRI扫描中接受LSD和安慰剂的静脉给药。通过低频波动幅度(ALFF)分析与疼痛处理相关的大脑区域,独立成分分析(ICA),功能连通性和动态休闲建模(DCM)。
    ALFF分析表明,由于与疼痛处理相关的神经网络中的调制,LSD有效地缓解了疼痛。ICA分析显示前扣带皮质(ACC)中更多的活动体素,丘脑(THL)-左,THL-右,脑岛皮层(IC)-右,顶叶盖(PO)-左,PO-右和额极点(FP)-安慰剂会话中的右比LSD会话中的右。与安慰剂会话相比,LSD会话中FP-左和IC-左的活动体素更多。在THL-左和PO-右之间以及PO-左和FP-左之间观察到功能性脑连接,安慰剂会话中的FP-右和IC-左。在LSD会议上,观察到PO-左与FP-左和FP-右的功能连接。左前脑岛皮层(LAIC)-LAIC之间的有效连接,LAIC-背外侧前额叶皮层(dlPFC)与次级体感皮层(SII)-dlPFC差异显著。最后,我们计算了fMRI生物标志物与临床疼痛标准之间的相关性.
    这项研究增强了我们对LSD效应对健康受试者疼痛的体系结构和神经行为的理解,并为认知科学和药理学领域的未来研究提供了巨大的希望。
    UNASSIGNED: We aimed to evaluate the effect of Lysergic acid diethylamide (LSD) on the pain neural network (PNN) in healthy subjects using functional magnetic resonance imaging (fMRI).
    UNASSIGNED: Twenty healthy volunteers participated in a balanced-order crossover study, receiving intravenous administration of LSD and placebo in two fMRI scanning sessions. Brain regions associated with pain processing were analyzed by amplitude of low-frequency fluctuation (ALFF), independent component analysis (ICA), functional connectivity and dynamic casual modeling (DCM).
    UNASSIGNED: ALFF analysis demonstrated that LSD effectively relieves pain due to modulation in the neural network associated with pain processing. ICA analysis showed more active voxels in anterior cingulate cortex (ACC), thalamus (THL)-left, THL-right, insula cortex (IC)-right, parietal operculum (PO)-left, PO-right and frontal pole (FP)-right in the placebo session than the LSD session. There were more active voxels in FP-left and IC-left in the LSD session compared to the placebo session. Functional brain connectivity was observed between THL-left and PO-right and between PO-left with FP-left, FP-right and IC-left in the placebo session. In the LSD session, functional connectivity of PO-left with FP-left and FP-right was observed. The effective connectivity between left anterior insula cortex (lAIC)-lAIC, lAIC-dorsolateral prefrontal cortex (dlPFC) and secondary somatosensory cortex (SII)-dlPFC were significantly different. Finally, the correlation between fMRI biomarkers and clinical pain criteria was calculated.
    UNASSIGNED: This study enhances our understanding of the LSD effect on the architecture and neural behavior of pain in healthy subjects and provides great promise for future research in the field of cognitive science and pharmacology.
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  • 文章类型: Journal Article
    研究了将冠状动脉造影解释为诊断工具的可靠性。此外,我们评估了观察者间冠状动脉病变变异对临床决策的影响.我们进行这项研究的动机之一是研究空白,我们的目标是获得有关不同心脏病专家之间观察者间变异性的最新信息。
    我们的目标是量化独立看过血管造影照片的心脏病专家的观察者间变异性。在先前的研究中,心脏病专家在对冠状动脉狭窄的侵入性冠状动脉造影的视觉评估中存在分歧并不少见。三位在冠状动脉造影方面有丰富经验的心脏病专家,包括每个病人的初级心脏病专家,独立阅读多伦多总医院200名患者的血管造影照片。
    我们的研究表明,所有参与的观察者之间的平均一致性为77.4%;因此,冠状动脉造影解释的观察者间变异性为22.6%.
    冠状动脉造影仍然是指导冠状动脉病变的金标准技术。有时候,冠状动脉造影结果低估或高估病变的功能严重程度。在通过有创冠状动脉造影解释冠状动脉狭窄的严重程度时,还应考虑观察者之间的变异性。这项研究表明,关于冠状动脉造影的观察者间变异性仍然存在(22.6%)。
    通俗易懂的语言总结:诊断冠状动脉狭窄的金标准方法,有创冠状动脉造影也有一些挑战。这些挑战之一是各种心脏病专家在确定每种冠状动脉狭窄的严重程度方面的差异。在这项研究中,我们重点研究了冠状动脉造影解释中观察者间变异性的差异.三名有冠状动脉造影经验的心脏病专家分别阅读了每位患者的冠状动脉造影照片。总的来说,选择多伦多总医院有血管造影史的患者200例。研究表明,所有参与的心脏病专家对冠状动脉造影结果的总体一致性为77.4%。换句话说,在读者中观察到22.6%的观察者间变异性。
    UNASSIGNED: The reliability of interpretation of coronary angiography as a diagnostic tool was investigated. Furthermore, the impact of interobserver variability of coronary lesions on clinical decision-making was assessed. One of our motivations to do this research was the research gaps and our aim to have up-to-date information regarding interobserver variability among different cardiologists.
    UNASSIGNED: Our objective was to quantify interobserver variability among cardiologists who have seen angiograms independently. Disagreement among cardiologists in the visual assessment of invasive coronary angiography of coronary artery stenosis is not uncommon in previous studies. Three cardiologists with extensive experience in coronary angiography, including the primary cardiologist of each patient, read the angiograms of 200 patients from Toronto General Hospital independently.
    UNASSIGNED: Our research showed the mean agreement among all participating observers was 77.4%; therefore, the interobserver variability of coronary angiography interpretation was 22.6%.
    UNASSIGNED: Coronary angiography is still the gold-standard technique for guidance regarding coronary lesions. Sometimes, coronary angiography results in underestimation or overestimation of a lesion\'s functional severity. Interobserver variability should also be considered when interpreting the severity of coronary stenoses via invasive coronary angiography. This research shows that interobserver variability regarding coronary angiograms is still present (22.6%).
    Plain language summary: The gold-standard method for diagnosing coronary stenosis, invasive coronary angiography has some challenges too. One of these challenges has been the difference among various cardiologists regarding determination of severity of each coronary stenosis. In this study, we focused on differences in interobserver variability in coronary angiography interpretation. Three cardiologists who were experienced in coronary angiography read each patient’s coronary angiogram separately. Overall, 200 patients with a history of angiography at Toronto General Hospital were selected randomly. The research showed that overall agreement among all participating cardiologists with regard to the reading of coronary angiograms was 77.4%. In other words, interobserver variability of 22.6% was seen among the readers.
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  • 文章类型: Journal Article
    分子是生命及其不同构象的基本组成部分(即,形状)至关重要地决定了它们在生物体中发挥的功能作用。低温电子显微镜(cryo-EM)允许获取单个分子的大图像数据集。计算低温EM的最新进展使学习构象景观的潜在变量模型成为可能。然而,解释这些潜在空间仍然是一个挑战,因为它们的个体维度通常是任意的。我们工作的关键信息是,可以将这种解释挑战视为独立成分分析(ICA)问题,在该问题中,我们寻求具有可识别性的模型。这意味着,他们有一个本质上独特的解决方案,代表构象潜在空间,该空间将分子在自然界中配备的不同自由度分开。因此,我们的目标是推进cryo-EM的计算领域超越可视化,因为我们将其与(非线性)ICA的理论框架联系起来,并讨论对可识别模型的需求,改进的指标,和基准。往前走,我们提出了增强cryo-EM潜在空间解纠缠的未来方向,完善评估指标,探索利用基于物理的生物分子系统解码器的技术。此外,我们讨论了时间分辨单粒子成像的未来技术发展如何实现非线性ICA模型的应用,该模型可以发现自然界分子的真实构象变化。对可解释的构象潜在空间的追求将使研究人员能够解开复杂的生物过程并促进有针对性的干预。这对更广泛的药物发现和结构生物学具有重要意义。更一般地说,潜在变量模型被广泛部署在许多科学学科中。因此,如果我们想从令人印象深刻的非线性神经网络模型转向数学基础方法,可以帮助我们学习有关自然的新知识,那么我们在这项工作中提出的论点在AI科学中具有更广泛的应用。
    Molecules are essential building blocks of life and their different conformations (i.e., shapes) crucially determine the functional role that they play in living organisms. Cryogenic Electron Microscopy (cryo-EM) allows for acquisition of large image datasets of individual molecules. Recent advances in computational cryo-EM have made it possible to learn latent variable models of conformation landscapes. However, interpreting these latent spaces remains a challenge as their individual dimensions are often arbitrary. The key message of our work is that this interpretation challenge can be viewed as an Independent Component Analysis (ICA) problem where we seek models that have the property of identifiability. That means, they have an essentially unique solution, representing a conformational latent space that separates the different degrees of freedom a molecule is equipped with in nature. Thus, we aim to advance the computational field of cryo-EM beyond visualizations as we connect it with the theoretical framework of (nonlinear) ICA and discuss the need for identifiable models, improved metrics, and benchmarks. Moving forward, we propose future directions for enhancing the disentanglement of latent spaces in cryo-EM, refining evaluation metrics and exploring techniques that leverage physics-based decoders of biomolecular systems. Moreover, we discuss how future technological developments in time-resolved single particle imaging may enable the application of nonlinear ICA models that can discover the true conformation changes of molecules in nature. The pursuit of interpretable conformational latent spaces will empower researchers to unravel complex biological processes and facilitate targeted interventions. This has significant implications for drug discovery and structural biology more broadly. More generally, latent variable models are deployed widely across many scientific disciplines. Thus, the argument we present in this work has much broader applications in AI for science if we want to move from impressive nonlinear neural network models to mathematically grounded methods that can help us learn something new about nature.
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  • 文章类型: Journal Article
    长期以来,人们一直认为沿海马长轴的结构差异是有意义的功能差异的基础。最近的发现表明,海马的数据驱动分割将海马分为10个簇的图,其中包括前内侧,前外侧,和后前外侧,中间,和后部组件。我们使用空间学习实验测试了任务和经验是否可以调节这种聚类,在该实验中,男性和女性参与者接受了训练,可以在类似Google街景的环境中虚拟导航一个新的社区。在培训初期和为期两周的培训期结束时,参与者在导航路线时进行了扫描。使用10簇地图作为理想模板,我们发现,最终很好地学习邻域的参与者的海马簇图与理想状态一致-即使在学习的第二天-而且他们的簇图在两周的训练期内没有偏离.然而,最终学习邻居的参与者开始时海马聚类图与理想模板不一致,尽管经过两周的培训,它们的簇映射可能会变得更加刻板。有趣的是,这种改进似乎是特定于路线的:经过一些早期改进,当一条新路线被导航时,参与者的海马图恢复到不那么刻板的组织。我们得出的结论是,海马聚集并不仅仅依赖于解剖结构,而是由解剖学的组合驱动,任务,而且重要的是,经验。尽管如此,而海马集群可以随着经验而改变,有效的导航依赖于功能性海马活动以刻板的方式聚集,突出沿海马前后轴和内侧外侧轴的最佳处理划分。意义声明海马是对记忆和导航重要的大脑区域。最近的研究表明,当人们休息时,海马体内的加工活动模式可以揭示海马体内的不同加工区域。我们通过在个体学习如何在新的虚拟现实环境中导航时检查海马体中的处理来扩展这项工作。我们的发现表明,不仅海马的活动模式可靠地将海马分为子组件,而且海马的干净功能分割与更强的导航性能有关。因此,虽然个人可以使用他们的海马体以不同的方式处理信息,可能有一个理想的模板来支持有效的空间学习。
    Structural differences along the hippocampal long axis are believed to underlie meaningful functional differences. Yet, recent data-driven parcellations of the hippocampus subdivide the hippocampus into a 10-cluster map with anterior-medial, anterior-lateral, and posteroanterior-lateral, middle, and posterior components. We tested whether task and experience could modulate this clustering using a spatial learning experiment where male and female participants were trained to virtually navigate a novel neighborhood in a Google Street View-like environment. Participants were scanned while navigating routes early in training and after a 2 week training period. Using the 10-cluster map as the ideal template, we found that participants who eventually learn the neighborhood well have hippocampal cluster maps consistent with the ideal-even on their second day of learning-and their cluster mappings do not deviate over the 2 week training period. However, participants who eventually learn the neighborhood poorly begin with hippocampal cluster maps inconsistent with the ideal template, though their cluster mappings may become more stereotypical after the 2 week training. Interestingly this improvement seems to be route specific: after some early improvement, when a new route is navigated, participants\' hippocampal maps revert back to less stereotypical organization. We conclude that hippocampal clustering is not dependent solely on anatomical structure and instead is driven by a combination of anatomy, task, and, importantly, experience. Nonetheless, while hippocampal clustering can change with experience, efficient navigation depends on functional hippocampal activity clustering in a stereotypical manner, highlighting optimal divisions of processing along the hippocampal anterior-posterior and medial-lateral axes.
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  • 文章类型: Journal Article
    背景:完整结肠系膜切除术(CME)和中央血管脱离是结直肠癌手术中非常重要的手术方法。术前和术中评估主要结直肠血管的解剖结构是必要的,以避免大量出血。尤其是在内窥镜手术中。据报道,罕见的异常病例中结肠动脉(MCA)和回结肠动脉(ICA)具有共同的干。
    方法:患者是一名73岁女性,在结肠镜检查中被诊断为升结肠癌。术前腹部对比增强计算机断层扫描证实,MCA和ICA具有共同的躯干。她接受了腹腔镜回盲肠切除术治疗升结肠癌,并进行了D3淋巴结清扫。术中进行吲哚菁绿荧光成像。确认血管分叉后,在MCA分叉的远端解剖ICA。该患者已作为门诊病人被随访,术后2年无复发迹象。
    结论:呈现一例具有独特血管分叉模式的升结肠癌。术前和术中评估结直肠主要血管对于预防围手术期及术后并发症非常重要。
    BACKGROUND: Complete mesocolic excision (CME) and central vascular detachment are very important procedures in surgery for colorectal cancer. Preoperative and intraoperative assessments of the anatomy of major colorectal vessels are necessary to avoid massive bleeding, especially in endoscopic surgery. A case with a rare anomaly in which the middle colic artery (MCA) and ileocolic artery (ICA) had a common trunk is reported.
    METHODS: The patient was a 73-year-old woman diagnosed with ascending colon cancer on colonoscopy. Preoperative abdominal contrast-enhanced computed tomography confirmed that the MCA and ICA had a common trunk. She underwent laparoscopic ileocecal resection for the ascending colon cancer with D3 lymph node dissection. Intraoperative indocyanine green fluorescence imaging was conducted. After confirming vessel bifurcation, the ICA was dissected at the distal end of the MCA bifurcation. The patient has been followed as an outpatient, with no signs of recurrence as of 2 years postoperatively.
    CONCLUSIONS: A case of an ascending colon cancer with a unique vascular bifurcation pattern was presented. Preoperative and intraoperative evaluations of the major colorectal vessels are very important for preventing perioperative and postoperative complications.
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  • 文章类型: Journal Article
    本文提出了一种先进的EEG伪影去除和运动图像分类方法,该方法结合了四类迭代滤波和滤波器组公共空间模式算法以及改进的深度神经网络(DNN)分类器。该研究旨在通过解决EEG伪影和复杂运动成像任务带来的挑战来提高BCI系统的准确性和可靠性。该方法首先引入FCIF,一种新颖的去除眼部伪影的技术,利用迭代滤波和滤波器组。FCIF的数学公式允许有效的伪影缓解,从而提高脑电数据的质量。串联,介绍了FC-FBCSP算法,扩展滤波器组公共空间模式方法来处理四类运动图像分类。改进的DNN分类器增强了FC-FBCSP特征的辨别能力,优化分类过程。本文展示了一个全面的实验装置,以BCI竞赛IV数据集2a和2b的利用为特色。详细的预处理步骤,包括过滤和特征提取,以数学上的严谨性呈现。结果证明了FCIF的显着伪影去除能力以及FC-FBCSP与ModifiedDNN分类器结合的分类能力。对比分析强调了所提出的方法相对于基线方法的优越性,该方法达到了98.575%的平均精度。
    This paper presents an advanced approach for EEG artifact removal and motor imagery classification using a combination of Four Class Iterative Filtering and Filter Bank Common Spatial Pattern Algorithm with a Modified Deep Neural Network (DNN) classifier. The research aims to enhance the accuracy and reliability of BCI systems by addressing the challenges posed by EEG artifacts and complex motor imagery tasks. The methodology begins by introducing FCIF, a novel technique for ocular artifact removal, utilizing iterative filtering and filter banks. FCIF\'s mathematical formulation allows for effective artifact mitigation, thereby improving the quality of EEG data. In tandem, the FC-FBCSP algorithm is introduced, extending the Filter Bank Common Spatial Pattern approach to handle four-class motor imagery classification. The Modified DNN classifier enhances the discriminatory power of the FC-FBCSP features, optimizing the classification process. The paper showcases a comprehensive experimental setup, featuring the utilization of BCI Competition IV Dataset 2a & 2b. Detailed preprocessing steps, including filtering and feature extraction, are presented with mathematical rigor. Results demonstrate the remarkable artifact removal capabilities of FCIF and the classification prowess of FC-FBCSP combined with the Modified DNN classifier. Comparative analysis highlights the superiority of the proposed approach over baseline methods and the method achieves the mean accuracy of 98.575%.
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  • 文章类型: Journal Article
    监测和预测区域地下水储量(GWS)波动是有效管理水资源的重要支持。因此,以山东省为例,重力恢复和气候实验(GRACE)和GRACE后续(GRACE-FO)的数据用于反演2003年1月至2022年12月的GWS波动以及水隙全球水文模型(WGHM),原位地下水量和水位数据。使用独立成分分析(ICA)分解时空特征,以及影响因素,如降水和人类活动,也进行了分析。为了预测GWS的短时间变化,支持向量机(SVM)与三种常用的长短期记忆方法(LSTM)结合使用,奇异谱分析(SSA),自回归移动平均模型(ARMA),作为比较。结果表明:(1)西部GWS的损失强度明显大于沿海地区。2003-2006年GWS急剧增加,2007-2014年GWS损失率为-5.80±2.28mm/a,2015-2022年GWS变化线性趋势为-5.39±3.65mm/a,可能主要受南水北调工程影响。GRACE与WGHM的相关系数为0.67,与原位地下水量和水位一致。(2)考虑移动平均线后的时间延迟,GWS与每月全球降水气候项目(GPCP)具有较高的正相关性。根据连续小波变换(CWT)方法具有相似的能量谱。此外,分析了影响GWS年度波动的因素,GWS与包括地下水开采消耗在内的原位数据之间的相关系数,农田灌溉量分别为0.80、0.71。(3)对于GWS预测,采用SVM方法进行分析,建立了三个训练样本,分别为180、204和228个月,拟合优度均高于0.97。相关系数分别为0.56、0.75、0.68;RMSE分别为5.26、4.42、5.65mm;NSE分别为0.28、0.43、0.36。SVM模型的短期预测性能优于其他方法。
    Monitoring and predicting the regional groundwater storage (GWS) fluctuation is an essential support for effectively managing water resources. Therefore, taking Shandong Province as an example, the data from Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) is used to invert GWS fluctuation from January 2003 to December 2022 together with Watergap Global Hydrological Model (WGHM), in-situ groundwater volume and level data. The spatio-temporal characteristics are decomposed using Independent Components Analysis (ICA), and the impact factors, such as precipitation and human activities, which are also analyzed. To predict the short-time changes of GWS, the Support Vector Machines (SVM) is adopted together with three commonly used methods Long Short-Term Memory (LSTM), Singular Spectrum Analysis (SSA), Auto-Regressive Moving Average Model (ARMA), as the comparison. The results show that: (1) The loss intensity of western GWS is significantly greater than those in coastal areas. From 2003 to 2006, GWS increased sharply; during 2007 to 2014, there exists a loss rate - 5.80 ± 2.28 mm/a of GWS; the linear trend of GWS change is - 5.39 ± 3.65 mm/a from 2015 to 2022, may be mainly due to the effect of South-to-North Water Diversion Project. The correlation coefficient between GRACE and WGHM is 0.67, which is consistent with in-situ groundwater volume and level. (2) The GWS has higher positive correlation with monthly Global Precipitation Climatology Project (GPCP) considering time delay after moving average, which has the similar energy spectrum depending on Continuous Wavelet Transform (CWT) method. In addition, the influencing facotrs on annual GWS fluctuation are analyzed, the correlation coefficient between GWS and in-situ data including the consumption of groundwater mining, farmland irrigation is 0.80, 0.71, respectively. (3) For the GWS prediction, SVM method is adopted to analyze, three training samples with 180, 204 and 228 months are established with the goodness-of-fit all higher than 0.97. The correlation coefficients are 0.56, 0.75, 0.68; RMSE is 5.26, 4.42, 5.65 mm; NSE is 0.28, 0.43, 0.36, respectively. The performance of SVM model is better than the other methods for the short-term prediction.
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  • 文章类型: Journal Article
    静息状态网络(RSN)的电生理基础仍在争论中。特别是,尚未确定能够同样很好地解释所有RSN的原则性机制。虽然脑磁图(MEG)和脑电图是确定RSN电生理基础的首选方法,还没有RSN的标准分析管道。在这篇文章中,我们比较了从MEG数据中提取RSN的两种主要的现有数据驱动分析策略,并介绍了第三种方法。第一种方法使用相位-振幅耦合来确定RSN。第二种方法通过对不同频段的希尔伯特包络进行独立分量分析来提取RSN,而第三种新方法使用奇异值分解代替。为了评估这些方法,我们将MEG-RSN与来自相同受试者的功能磁共振成像(fMRI)-RSN进行了比较。总的来说,可以使用所有三种技术用MEG提取RSN,与特定组的fMRI-RSN匹配。有趣的是,与两种现有方法相比,基于SVD的新方法与七个fMRI-RSN中的五个产生了显着更高的对应关系。重要的是,用这种方法,除视觉网络外,所有网络在一个频带内与fMRI网络的对应度最高.因此,我们提供了对fMRI-RSN的电生理基础的进一步见解。这些知识对于电生理连接体的分析将是重要的。
    The electrophysiological basis of resting-state networks (RSN) is still under debate. In particular, no principled mechanism has been determined that is capable of explaining all RSN equally well. While magnetoencephalography (MEG) and electroencephalography are the methods of choice to determine the electrophysiological basis of RSN, no standard analysis pipeline of RSN yet exists. In this article, we compare the two main existing data-driven analysis strategies for extracting RSNs from MEG data and introduce a third approach. The first approach uses phase-amplitude coupling to determine the RSN. The second approach extracts RSN through an independent component analysis of the Hilbert envelope in different frequency bands, while the third new approach uses a singular value decomposition instead. To evaluate these approaches, we compare the MEG-RSN to the functional magnetic resonance imaging (fMRI)-RSN from the same subjects. Overall, it was possible to extract RSN with MEG using all three techniques, which matched the group-specific fMRI-RSN. Interestingly the new approach based on SVD yielded significantly higher correspondence to five out of seven fMRI-RSN than the two existing approaches. Importantly, with this approach, all networks-except for the visual network-had the highest correspondence to the fMRI networks within one frequency band. Thereby we provide further insights into the electrophysiological underpinnings of the fMRI-RSNs. This knowledge will be important for the analysis of the electrophysiological connectome.
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  • 文章类型: Journal Article
    立体脑电图是一种强大的脑内脑电图记录方法,用于术前评估癫痫。它包括在患者的大脑中植入深度电极,以记录电活动并绘制癫痫区,应该切除以使患者无癫痫发作。立体脑电图具有很高的空间精度和信噪比,但在探索的大脑区域的覆盖范围仍然有限。因此,植入可能提供癫痫发生区域的次优采样。我们研究了通过对立体脑电图信号进行源定位来改善次优立体脑电图记录的潜力。我们建议结合独立成分分析,连通性措施,以识别感兴趣的组件,和分布式源建模。这种方法在两名患者身上进行了测试,第一个未能表征癫痫发生区,第二个未能给出更好的诊断。我们证明了对第一次立体脑电图记录进行的发作和发作间源定位与第二次立体脑电图探索的发现相匹配。我们的发现表明,独立成分分析,然后在感兴趣的地形图上进行源定位是在植入次优情况下检索癫痫发生区的有希望的方法。
    Stereoelectroencephalography is a powerful intracerebral EEG recording method for the presurgical evaluation of epilepsy. It consists in implanting depth electrodes in the patient\'s brain to record electrical activity and map the epileptogenic zone, which should be resected to render the patient seizure-free. Stereoelectroencephalography has high spatial accuracy and signal-to-noise ratio but remains limited in the coverage of the explored brain regions. Thus, the implantation might provide a suboptimal sampling of epileptogenic regions. We investigate the potential of improving a suboptimal stereoelectroencephalography recording by performing source localization on stereoelectroencephalography signals. We propose combining independent component analysis, connectivity measures to identify components of interest, and distributed source modelling. This approach was tested on two patients with two implantations each, the first failing to characterize the epileptogenic zone and the second giving a better diagnosis. We demonstrate that ictal and interictal source localization performed on the first stereoelectroencephalography recordings matches the findings of the second stereo-EEG exploration. Our findings suggest that independent component analysis followed by source localization on the topographies of interest is a promising method for retrieving the epileptogenic zone in case of suboptimal implantation.
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