Recovering EEG brain signals: artifact suppression with wavelet enhanced independent component analysis

Independent component analysis (ICA) has been proven useful for suppression of artifacts in EEG recordings. It involves separation of measured signals into statistically independent components or sources, followed by rejection of those deemed artificial. We show that a "leak" of cerebral activity of interest into components marked as artificial means that one is going to lost that activity. To overcome this problem we propose a novel wavelet enhanced ICA method (wICA) that applies a wavelet thresholding not to the observed raw EEG but to the demixed independent components as an intermediate step. It allows recovering the neural activity present in "artificial" components. Employing semi-simulated and real EEG recordings we quantify the distortions of the cerebral part of EEGs introduced by the ICA and wICA artifact suppressions in the time and frequency domains. In the context of studying cortical circuitry we also evaluate spectral and partial spectral coherences over ICA/wICA-corrected EEGs. Our results suggest that ICA may lead to an underestimation of the neural power spectrum and to an overestimation of the coherence between different cortical sites. wICA artifact suppression preserves both spectral (amplitude) and coherence (phase) characteristics of the underlying neural activity.     

医学独立实验室对上海市浦东新区社会办医疗机构临床检验状况的作用

摘要医学独立实验室是具有独立法人资格专业从事医学检验的一类医疗机构。近年来,随着我国医药卫生体制改革的不断深化,该类医疗机构得到了迅速发展,目前浦东新区共有医学独立实验室6家。医学独立实验室能够节省检验成本、提高校验效率、改善检验质量,对于改善浦东区社会办医疗机构的临床检验状况起到一定的积极作用,但医学独立实验室也存在过分追求经济效益,超出诊疗科目登记范围开展检验项目等问题。为此,相关卫生行政管理部门需从加大宣传、加强监管等方面,对其加以引导,促其健康发展。     

降钙素原对免疫功能异常的脓毒症患者病情评估和预后判断

目的 探讨降钙素原(PCT)对脓毒症患者病情评估和预后判断的价值.方法 回顾性分析2011年10月至2012年9月武汉大学人民医院急诊监护室、重症监护室、呼吸监护室收治的脓毒症患者278例,其中免疫功能正常患者122例,免疫功能异常患者156例.根据APACHEⅡ评分将患者分为低、中、高危3组.分析PCT质量浓度与APACHEⅡ评分,首次PCT质量浓度与入院7d病死率之间的相关性.并比较首次PCT质量浓度与动态监测PCT对患者预后的预测价值.结果 Pearson相关分析结果显示,患者PCT质量浓度与即时APACHEⅡ评分存在显著正相关性(r =0.979,P＜0.05).患者首次PCT质量浓度与入院7d病死率也存在显著正相关性(r=0.826,P＜0.05).多因素logistic回归分析显示入院首次PCT质量浓度和APACHEⅡ评分与脓毒症患者7d预后差异具有统计学意义(首次PCT值浓度OR=1.77,95％CI=1.28,3.83,P=0.0023).与动态监测PCT比较,分别以免疫功能正常患者PCT≥7.18 ng/ml,免疫功能异常患者PCT≥3.52 ng/ml为脓毒症患者入院7d死亡的最佳预警界值,敏感性差异无统计学意义,特异性低于动态监测PCT.结论 PCT质量浓度并且不受糖皮质激素或免疫抑制剂的影响可以鉴别免疫功能异常的患者是否合并细菌感染.入院首次PCT值浓度是预测脓毒症患者7d死亡的独立危险因素.与免疫功能正常的患者比较,免疫功能异常患者提示短期恶性预后的PCT预警界值更低.     

Independent component analysis applied to the removal of motion artifacts from electrocardiographic signals

Electrocardiographic (ECG) signals are affected by several kinds of artifacts that may hide vital signs of interest. In this study we apply independent component analysis (ICA) to isolate motion artifacts. Standard or instantaneous ICA, which is currently the most addressed ICA model within the context of artifact removal, is compared to two other ICA techniques. The first technique is a frequency domain approach to convolutive mixture separation. The second is based on temporally constrained ICA, which enables the estimation of only one component close to a particular reference signal. Performance indexes evaluate ECG complex enhancement and relevant heart rate errors. Our results show that both convolutive and constrained ICA implementations perform better than standard ICA, thus opening up a new field of application for these two methods. Moreover, statistical analysis reveals that constrained ICA and convolutive ICA do not significantly differ concerning heart rate estimation, even though the latter overcomes the former in ECG morphology recovery.     

Muscle Artifact Removal from Human Sleep EEG by Using Independent Component Analysis

Muscle artifacts are typically associated with sleep arousals and awakenings in normal and pathological sleep, contaminating EEG recordings and distorting quantitative EEG results. Most EEG correction techniques focus on ocular artifacts but little research has been done on removing muscle activity from sleep EEG recordings. The present study was aimed at assessing the performance of four independent component analysis (ICA) algorithms (AMUSE, SOBI, Infomax, and JADE) to separate myogenic activity from EEG during sleep, in order to determine the optimal method. AMUSE, Infomax, and SOBI performed significantly better than JADE at eliminating muscle artifacts over temporal regions, but AMUSE was independent of the signal-to-noise ratio over non-temporal regions and markedly faster than the remaining algorithms. AMUSE was further successful at separating muscle artifacts from spontaneous EEG arousals when applied on a real case during different sleep stages. The low computational cost of AMUSE, and its excellent performance with EEG arousals from different sleep stages supports this ICA algorithm as a valid choice to minimize the influence of muscle artifacts on human sleep EEG recordings.     

Does processing of emotional facial expressions depend on intention? Time-resolved evidence from event-related brain potentials

We assessed the automaticity of emotional face processing with respect to the intentionality criterion, holding that automatic processes are triggered independently of intention. For this purpose, we observed emotion processing in event-related brain potential (ERP) components under five different task conditions. ERP components included the P1, N170, the early posterior negativity (EPN), and the late positive complex (LPC). Enhanced processing at perceptual stages as indicated by P1, N170, and EPN effects occurred independently of intention in angry expressions. In contrast, the emotion-related LPC, a putative manifestation of higher-level, more elaborative processing stages, depended on the intentional state of the participants. This suggests an automatic threat-related processing bias at perceptual stages, while higher cognitive emotion encoding is subject to voluntary control. Moreover, an independent component analyses (ICA) showed that EPN and LPC activity occurred simultaneously, indicating perceptual and higher cognitive emotion encoding to occur in parallel.     

培育“学院文化”,促进独立学院内涵式

独立学院文化建设中存在传承与创新的矛盾、民企文化和大学文化冲突的问题.坚持以“人”为中心的理念,协调传承与创新的关系,融汇民企文化和大学文化优点于一体,培育独立学院独特的精神文化、和谐的制度文化和统一的物质文化,形成具有自身文化底蕴特色的“学院文化”,为丰富、完善独立学院内涵式发展体系的理论与实践提供借鉴.     

海外医疗援助中独立型门诊展开的护理工作体会

目的 探讨总结我海军首次在海外展开独立型门诊的护理工作方法.方法 明确护理工作目标,关注细节,从工作前期的充分准备,到展开后对场所区域的设置及对护理人员的分工,细化流程,突出重点,完成护理任务.结果 达成既定目标,确保护理工作展开有序,涉外护理沟通有效,防疫工作实施有力,护理安全督导有方.结论 在海外非医疗场所展开独立...     

医学独立学院专业课程体系与教学质量问卷调查及分析报告——以安徽医科大学临床医学院为例

针对新型教育模式-独立医学院的现状和实际,通过对临床医学院学生的分层抽样调查,了解当前教学课程体系和教学质量现状,为构建独立医学院教学质量监控体系,为培养合格的、创新型的高等医药人才提供实践指导和理论依据。