抑郁症的ERPs电流源模型与特征分析

采用3-刺激视觉oddball实验范式,研究干扰子刺激和靶刺激条件下抑郁症患者的大脑电流源的异常电流响应过程.分别采集了抑郁症和健康受试者的64导联脑电,以该实验任务的功能磁共振激活簇空间坐标为约束条件,建立了干扰子刺激和靶刺激条件下事件相关电位的脑区域源模型,通过脑源重建法计算得到14个区域源的源电流波形,经非配对t检验和置换检验后发现:在靶刺激条件下,抑郁症患者的右侧脑岛、右侧中央前沟在P300晚期产生的源电流幅度与正常人有显著差异(P＜0.05),它引起右侧头皮前额区的异常负电位.在干扰子刺激条件下,患者的左侧中央前沟在P300晚期产生的源电流与正常人有明显差异,差异显著性具有趋势意义(P=0.087),它引起左侧前额区的异常近零电位.结果表明:通过源电流计算发现了抑郁症患者的中央前沟和脑岛的P300活动发生显著异常.     

视觉靶刺激和干扰子刺激响应过程中的脑电流源模型分析

采用3-刺激视觉oddball实验范式,研究大脑离散电流源在干扰子刺激和靶刺激响应过程中的电流时间过程。本文采集了健康受试者的64导联头皮脑电(EEG)数据,通过3-刺激范式,既检测到人脑在识别小概率事件(靶刺激和干扰子刺激)过程中产生的P300电位的P3b成分;又测得P300电位的P3a成分,P3a主要在干扰子刺激响应过程中产生。本文用相同实验范式下的磁共振激活簇空间坐标作为约束条件,建立了干扰子刺激和靶刺激事件相关电位(ERPs)的区域源模型,区域源模型的电流计算分析表明P3b的主要神经源包括双侧下顶叶、双侧后顶叶皮层和双侧颞下皮层,而P3a的主要神经源包括双侧脑岛、双侧中央前沟和扣带回等额叶皮层。研究结果表明对靶刺激的脑处理涉及顶叶、颞下皮层和左侧脑岛等参与的刺激驱动注意过程、目标引导注意过程、视觉形状分类与记忆提取等,而对干扰子刺激的脑处理则主要涉及右侧脑岛、扣带回等完成的注意转移、注意资源的重新分配过程。     

音调对音乐情绪反应影响的脑电功能连接研究

目的 探究在倾听不同情绪属性的音乐时音调的变化对大脑功能连通性的影响，以期揭示音调对音乐情绪反应影响的神经机制。方法 首先选取能分别诱发出积极情绪和消极情绪的音乐并制作其升调和降调版本，然后采集10名健康大学生（男、女各5名）听不同版本音乐时的32通道头皮脑电数据，最后分成delta、theta、alpha和beta四个频段计算衡量不同电极间功能连接强弱的指标加权相位滞后指数（weighted phase lag index,wPLI），分析不同条件下脑功能连通性的差异。结果 听消极音乐时，降调版本与原版相比在delta频段下的功能连接显著增强。听积极音乐时，在alpha和beta频段下，与原版相比升高音调显著增强了功能连接，而降低音调显著减弱了功能连接。结论 降低消极音乐的音调使得大脑低频功能连接增加，产生了更放松的音乐体验，表现为效价评分升高；音调的改变会导致听情绪音乐时的大脑功能连通性主要在alpha和beta频段发生变化，表明受试者的音乐感知受到影响，从而导致行为学评分改变。     

一种基于汉语音调信息的电子耳蜗语音信号处理新方案

本文在连续交替取样(Continuous Inteleaved     

时空模型结合模拟退火进行脑磁源的定位

脑磁源的定位问题是脑磁图（magnetoencephalography,MEG)研究的一个基本问题，其中多偶极子定位是脑磁逆问题研究当中的难点。本文通过研究脑磁图的时空模型STSM（spatio-temoral source modeling)，提出将时空模型与模拟退火相结合进行多偶极子的定位，以克服其他优化方法易落入局部极小的不足，时空模型中偶极子参数经分解可分为线性部分和非线形部分，只对非线性部分进行模拟退火优化大大降低了优化空间的维数。通过与MUSIC（MUltiple SIgnal Classification)方法的比较，发现将时空模型与模拟退火相结合可以相对降低对源信号独立性的要求。     

基于语音预训练模型的抑郁症识别研究

针对数量日益增多的抑郁症患者群体,本文提出一种通过语音信号有效识别抑郁症的人工智能方法,以提高诊断和治疗效率。首先,通过微调语音到特征向量模型2.0(wav2vec 2.0)的预训练模型对语音进行编码和上下文化,从而获得高质量的语音特征;然后,应用情感障碍分析的公用数据集——绿野仙踪忧虑分析访谈语料库（DAIC-WOZ）数据集验证上述模型。结果显示,在抑郁症识别的二分类任务中,该方法在精确率方面达到了93.96%、召回率达到了94.87%、F1分数达到了94.41%,总体分类准确率达到96.48%。在评估抑郁症严重程度的四分类任务中,精确率均达到92.59%及以上,召回率均达到92.89%及以上,F1分数均达到93.12%以上,总体分类准确率达到94.80%。基于上述结果证明,本文提出的方法在小样本情况下有效提升了分类的准确率,对于抑郁症的识别和严重程度评估效果良好。未来,该方法有望在抑郁症的诊断中起到辅助支持的作用。     

人兴奋状态的脑波模型及脑内敏感区定位

研究目的是确定人兴奋时的脑波特征及兴奋发生源在脑区的解剖位置，通过饮用定量的咖啡使人摄入咖啡因形成兴奋，同时用128导联数字脑电系统采集脑电EEG（electroencephalo-graph）信号，与饮用咖啡之前的安静状态的EEG信号进行功率谱比对。发现两者之间有明显的区别，表现出人在兴奋时的脑波特征是10Hz以下的低频成分受到明显抑制，同时高频成分明显增加，特别是产生一个38Hz的波峰，高度在200μV左右。利用ASA源分析软件对兴奋的发生源区域进行定位，发现兴奋的发生区域集中在脑桥腹侧正中下部的区域。     

脑炎患者的脑电地形图、脑电图与CT的对比分析

本文对45例脑炎患者的BEAM、EEG与CT进行对比分析,结果表明,BEAM的阳性率91.2％高于EEG81.2％与CT24.4％。提示在脑功能性或器质性损害的早期,脑结构未明显受损,CT可无异常发现,而BEAM通过定量定位反映脑机能变化,因而在颅内疾病诊断中有重要价值。     

脑源性神经营养因子与癫痫

癫痫发作可诱导海马内脑源性神经营养因子(BDNF)水平上调,进而激活海马门区及CA3区腔隙层的TrkB受体,通过促进兴奋性神经递质释放等效应加强海马通路尤其是苔状纤维的兴奋性突触传递,从而导致持续的高度兴奋状态;而阻断BDNF信号转导通路则可抑制癫痫发生.提示BDNF在癫痫发作过程中具有重要作用,进一步阐明其细胞分子机制将为探索癫痫治疗手段提供新途径.     

脑源性神经营养因子与缺血性脑血管病的研究进展

脑源性神经营养因子（BDNF）为神经营养因子（NTFs）中的一种，是1982年Barde及其同事从猪脑提取液中获得的分子量为12．3KD①的碱性蛋白质，有119个氨基酸组成，含有3对二硫键，等电点为10左右。研究表明BDNF是一种在神经元损伤后再生修复和防止神经细胞退行性变等方面发挥极其重要作用的细胞因子。近年来神经细胞培养和动物实验研究表明，     

Source Localization of P300 from Oddball, Single Stimulus, and Omitted-Stimulus Paradigms

Three different auditory stimulus paradigms were used to elicit P300 potentials. Normal subjects were tested on the classical rare target stimulus, single-stimulus and omitted-stimulus conditions. Noninvasive identification of the cerebral sources of the event-related potentials (ERPs) was performed using spatio-temporal multiple dipole modeling (BESA software) with individually sized spherical head models. The grand average data of each condition was first independently modeled and these models were used as starting values for modeling each individual subject's data. Models for the rare-stimulus condition and single-stimulus condition both consisted of 6 dipoles. Models for the omitted-stimulus condition consisted of 2 dipoles. The dipole locations of the final individual 6-dipole models for the rare and single-stimulus conditions did not differ significantly from each other or from one previous result obtained from a another group of subjects (Tarkka et al. 1995). Super-imposition of the dipole coordinates on the sterotaxic brain atlas suggests that bilateral deep medial temporal lobe structures are the major contributors to rare and single-stimulus P300s. Because both the wave form morphology and the source model of the P300 elicited by single stimulus were close to those of the rare-stimulus P300 it may be that the underlying neural mechanisms eliciting these P300 potentials are essentially the same.     

Multiple Equivalent Current Dipole Source Localization of Visual Event-Related Potentials During Oddball Paradigm With Motor Response

Event-related potentials (ERPs) during a visual oddball paradigm with button-pressing responses were recorded in 12 right-handed subjects from 32 scalp electrodes. The single equivalent current dipole (ECD) of the target C1 (weak occipito-parietal negativity from 30-80ms) was consistently located at the primary visual cortex. From the 4-ECD localization of the target P1/N1 (temporally coincident frontal positivity and occipito-temporal negativity), it was suggested that this complex reflected activities from distributed sources along both dorsal occipito-parietal and ventral occipito-temporal areas. The stable multiple ECD solutions for the target P3b were chosen as those including the left primary motor and/or sensorimotor dipole and satisfying goodness-of-fit (GOF) of more than 98% and confidence limit (CL) of less than 1mm. The obtained frontal dipoles were discussed in terms of visual working memory and sustained attention in reference to the previous PET, fMRI and MEG studies. The distributed multiple ECDs may suggest that P3 should be interpreted as being the embodiment of the cortico-limbic-thalamic network which involves Halgren and Marinkovic's emotional and behavioral model and Mesulam's attentional circuit.     

Response- and Stimulus-Related ERP Asymmetries in a Tonal Oddball Task: A Laplacian Analysis

Previous studies have found greater P3 amplitude over right than left hemisphere sites in a tonal oddball task with a reaction time (RT) response. This asymmetry had a central topography, and interacted with response hand. Identification of the processes underlying these asymmetries requires the use of additional methods for separating response- and stimulus-related contributions. We applied local Hjorth and spherical spline algorithms to compute surface Laplacian topographies of ERP data recorded from 30 scalp electrodes in a pooled sample of 46 right-handed healthy adults. For both methods, the current sources underlying the late positive complex were largest at medial parietal regions, but were asymmetric at central and frontocentral sites. Although a frontocentral sink contralateral to the response hand contributed to the asymmetry of the classic P3 peak, the source asymmetry was most robust after the sink had resolved. The late source was largest at electrode C4 for right hand responses, and was further enhanced in subjects showing a dichotic left ear advantage, but was unrelated to response speed. We conclude that the right hemisphere source reflects an interaction of response-related asymmetries with right hemisphere processes responsible for pitch discrimination.     

Brain Electrical Source Differences between Depressed Subjects and Healthy Controls

Many brain regions show metabolic and perfusion abnormalities in major depressive disorder (MDD), including anterior cingulate and prefrontal cortices. Some of these same areas also show abnormal function with low resolution electromagnetic tomography (LORETA). However, LORETA results are not always consistent across studies, nor with findings from other imaging modalities. These discrepancies may be due, among other factors, to the sensitivity of EEG source localization to different electrode montages. Thirty-six channel EEG was collected from healthy controls and age- and gender-matched unmedicated subjects with MDD (n = 74). EEGs were analyzed with LORETA to assess resting state current density at each of 2,394 cortical voxels. For comparison to previous studies, LORETA was performed using all electrodes or with specific prefrontal electrodes removed. Voxel-by-voxel differences between the depressed and healthy groups were calculated using non-parametric statistics. MDD subjects showed significantly elevated current density in delta, theta, alpha, beta1, and beta2 frequency bands relative to controls in anterior cingulate and prefrontal cortices. Removal of certain prefrontal electrodes from input to LORETA decreased or eliminated significant differences between groups. LORETA detects differences in brain activity between MDD subjects and healthy controls that are consistent with previous findings using other imaging modalities. Inconsistent findings among LORETA studies, and between LORETA studies and those using other functional imaging techniques, may result from differences in electrode montages.     

Multiple Dipole Analysis of Visual Event-Related Potentials During Oddball Paradigm with Silent Counting

In order to cope with the non-uniqueness of multiple equivalent current dipole source (ECD) solutions, a priori knowledge about P300 generators of visual event-related potentials (ERPs) during an oddball paradigm with silent counting task was incorporated into the multiple ECD localization method. Four-ECD solutions for the target P300 were selected which had the left frontal ECD. The rest of the ECDs were localized to the inferior parietal lobule, the hippocampal formation and subcortical region. By comparing the present results with those on the visual ERPs with button-pressing task, the P300 dipoles common to both the tasks were located at the frontal cortices, the hippocampal formation and the thalamus, suggesting that these structures are the main P300 generators.     

独立分量分析在脑电信号处理中的应用及研究进展

独立分量分析(independent component analysis,ICA)方法是从一组观测信号中提取统计独立分量的方法.因为用这种方法分解出的各信号分量之间是相互独立的,而测得的脑电信号往往包含若干相对独立的成分,所以用它来分解脑电信号,所得的结果更具有生理意义,有利于去除干扰和伪差.本文简要地回顾了ICA的发展历史和主要算法,综述了它在脑电信号处理中的应用及研究进展,并指出了需要进一步研究解决的问题.     

Mapping attention during gameplay: Assessment of behavioral and ERP markers in an auditory oddball task

Video games are enjoyed most when the level and speed of the game match the players' skills. An optimal balance between challenges and skills triggers the subjective experience of “flow,” a focused motivation leading to a feeling of spontaneous joy. The present research investigates the behavioral and neural correlates of a paradigm aimed to assess the players' subjective experience during gameplay. Attentional engagement changes were assessed first at the behavioral level and in a second stage by means of EEG recordings. An auditory novelty oddball paradigm was implemented as a secondary task while subjects played in three conditions: boredom, frustration, and flow. We found higher reaction times and error rates in the flow condition. In a second stage, EEG time domain analysis revealed a significantly delayed response‐locked frontocentral negative deflection during flow, likely signaling the reallocation of attentional resources. Source reconstruction analyses showed that the brain regions responsible for the genesis of this negativity were located within the medial frontal cortex. Frequency domain analyses showed a significant power increase only in the alpha band for the flow condition. Our results showed that this alpha power enhancement was correlated with faster reaction times. This suggests that frontal alpha changes recorded as maximal at the midfrontal lines during flow might be related to inhibitory top‐down cognitive control processes.     

Discriminant Analysis and Equivalent Source Localization of the EEG Related to Cognitive Functions

Discriminant analysis and EEG source localization methods were employed to compare groups of normal subjects during different cognitive conditions using 43-channel EEG recordings in the alpha (8-13 Hz) frequency band. Recordings were obtained from 69 dextral females during 2 passive conditions, Eyes-Open and Eyes-Closed, and 2 active conditions, Word-Finding and Dot-Localization. The cross-spectral matrix between all of the electrode sites was used to characterize the EEGs obtained during each condition. The subjects were partitioned into training and test sets and quadratic discriminant functions were constructed from the training sets to classify the EEGs. The discriminant functions successfully classified both the training and test sets at rates approaching 80%. The classification was repeated using only the diagonal (power spectral) elements of the cross-spectral matrices in the discriminant functions and this approach was successful in discriminating between the EEGs from the passive cognitive conditions but failed to discriminate between the EEGs from the active conditions. Source localization using a modified MUSIC algorithm indicated that the centers of brain electrical activity that distinguished the Eyes-Closed condition from the Eyes-Open condition were located in the medial occipital and right frontal regions. Centers of electrical activity that distinguished the Word-Finding condition from the Dot-Localization condition were located in the right medial posterior and left temporal regions. Validation of the locations of the centers of activity was accomplished by repeating the classification procedures using the spatial patterns generated on the scalp by dipole current sources placed at these locations.     

基于fMRI加权约束的FOCUSS迭代脑电源定位方法及其初步应用

脑电(Electroencephalography, EEG)和功能磁共振(Functional magnetic resonance imaging, fMRI)技术的结合,可以实现两者优势的互补,获得更加合理的源定位结果.本文报道的是一种将fMRI先验信息结合到脑电源定位中的新方法.在该方法中,先利用SPM方法计算获得fMRI的统计映射参数,然后将基于计算获得的统计参数构造的权矩阵结合到FOCUSS的迭代过程中,对脑电的反演提供具有fMRI先验空间位置信息的约束,提高脑电的源空间定位精度,从而获得更加合理的定位结果.通过对一形状知觉实验fMRI和脑电数据的结合定位分析,结果初步证实了改进方法能获得和生理更加一致的结果.