Sources of the Electrical Activity of Brain Areas Involving in Imaginary Movements

Neuroscience and Behavioral Physiology - We describe the most significant sources of electrophysiological brain activity identified during use of a brain–computer interface based on...     

Brain Electrical Activity Evoked by Mental Formation of Auditory Expectations and Images

Evidence for the brain's derivation of explicit expectancies in an ongoing sensory context has been well established by studies of the P300 and processing negativity (PN) components of the event-related potential (ERP). Emitted potentials generated in the absence of sensory input by unexpected stimulus omissions also exhibit a P300 component and provide another perspective on patterns of brain activity related to the processing of expectancies. The studies described herein extend earlier emitted potential findings in several aspects. First, high-density (128-channel) EEG recordings are used for topographical mapping of emitted potentials. Second, the primary focus is on emitted potential components preceding the P300, i.e. those components that are more likely to resemble ERP components associated with sensory processing. Third, the dependence of emitted potentials on attention is assessed. Fourth, subjects' knowledge of the structure of an auditory stimulus sequence is modulated so that emitted potentials can be compared between conditions that are identical in physical aspects but differ in terms of subjects' expectations regarding the sequence structure. Finally, a novel task is used to elicit emitted potentials, in which subjects explicitly imagine the continuations of simple melodies. In this task, subjects mentally complete melodic fragments in the appropriate tempo, even though they know with absolute certainty that no sensory stimulus will occur. Emitted potentials were elicited only when subjects actively formed expectations or images. The topographies of the initial portion of the emitted potentials were significantly correlated with the N100 topography elicited by corresponding acoustic stimuli, but uncorrelated with the topographies of corresponding silence control periods.     

Asymmetrical Brain Electrical Activity Discriminates Between Psychometrically-Matched Verbal and Spatial Cognitive Tasks

This study compared the asymmetry of different features of brain electrical activity during the performance of a verbal task (word finding) and a spatial task (dot localization) that had been carefully matched on psychometric properties and accompanying motor activity. Nineteen right-handed subjects were tested. EEG was recorded from F3, F4, C3, C4, P3, and P4, referred to both CZ and computer-derived averaged-ears references, and Fourier transformed. Power in the delta, theta, alpha, and beta bands was computed. There were significant Task X Hemisphere effects in all bands for CZ-referenced data and for the alpha and beta bands for ears-referenced data. The effects were always either greater power suppression in the hemisphere putatively most engaged in task processing or greater power in the opposite hemisphere. Correlations between EEG and task performance indicated that CZ-referenced parietal alpha asymmetry accounted for the most variance in verbal task performance. Power within individual hemispheres or across hemispheres was unrelated to task performance. The findings indicate robust differences in asymmetrical brain physiology that are produced by well-matched verbal and spatial cognitive tasks.     

Diurnal Alterations of Brain Electrical Activity in Healthy Adults: A LORETA Study

EEG background activity was investigated by low resolution brain electromagnetic tomography (LORETA) to test the diurnal alterations of brain electrical activity in healthy adults. Fourteen right-handed healthy male postgraduate medical students were examined four times (8 a.m., 2 p.m., 8 p.m. and next day 2 p.m.). LORETA was computed to localize generators of EEG frequency components. Comparing the EEG activity between 2 p.m. and 8 a.m., increased activity was seen (1) in theta band (6.5–8 Hz) in the left prefrontal, bilateral mesial frontal and anterior cingulate cortex; (2) in alpha2 band (10.5–12 Hz) in the bilateral precuneus and posterior parietal cortex as well as in the right temporo-occipital cortex; (3) in beta1-2-3 band (12.5–30 Hz) in the right hippocampus and parieto-occipital cortex, left frontal and bilateral cingulate cortex. Comparing the brain activity between 8 p.m. and 8 a.m., (1) midline theta activity disappeared; (2) increased alpha2 band activity was seen in the left hemisphere (including the left hippocampus); and (3) increased beta bands activity was found over almost the whole cortex (including both of hippocampi) with the exception of left temporo-occipital region. There were no significant changes between the background activities of 2 p.m. and next day 2 p.m. Characteristic distribution of increased activity of cortex (no change in delta band, and massive changes in the upper frequency bands) may mirror increasing activation of reticular formation and thus evoked thalamocortical feedback mechanisms as a sign of maintenance of arousal.     

五音乐曲对精神分裂症脑电活动率的影响

目的 :观察五音乐曲刺激对精神分裂症患者脑电活动产生的影响。方法 :选取 2 0例精神分裂症患者和 10名正常对照 ,分别记录安静时段及聆听五音乐曲时段的脑电图 ,将脑电信号转化为功率数值 ,将 β/α定义为脑电活动率。 结果 :1、正常人与精神分裂症患者的脑电活动率在安静状态差异无显著性 (P >0 0 5 )。在听乐曲时患者的脑电活动率在C3、T3、T4、T5导联中 ,明显高于正常人 (P <0 0 5 )。 2、正常人在安静状态和听乐曲时其左右脑脑电活动率差异无显著性 (P >0 0 5 )。精神分裂症患者在安静状态左右脑脑电活动率在O1、O2及T5、T6导联间差异有显著意义 (P <0 0 5 ) ,并且听乐曲时在P3、P4和C3、C4以及F7、F8导联间差异有显著意义 (P <0 0 5 )。结论 :在五音乐曲的刺激下 ,精神分裂症患者的脑电反应与正常人不同。     

Word-Association Latency in Normal Children During Development and the Relation of Brain Electrical Activity

Electroencephalograms (EEGs) were recorded in a group of 37 normal boys aged 92–206 months during performance of a word-association task. Ss were instructed to say the first word that came to mind, as quickly as possible, following presentation of each of 18 stimulus words that were familiar to young children. Word-association latency, or the associative reaction time (RT), was analyzed only for trials in which a stimulus word evoked the same response word. Younger children were found to have significantly longer associative RTs than older children, with associative RT decreasing with increasing age according to a reciprocal power-law function. Comparison of this function with similar functions relating simple and disjunctive RT to age, suggested that the longer word-association latencies of children could not be attributed merely to developmental differences in non-verbal processes or processes concerned primarily with speed of responding. Sufficient EEG data for analysis were available for only 5 of the stimulus-response word combinations, and for these data, average EEG period from the left hemisphere was significantly different from (longer than) EEG period from the right hemisphere. Results of a partial-correlation analysis showed that left-hemisphere differences in EEG period between Ss can account, in part, for the relationship between associative RT and age, while right-hemisphere differences in EEG period cannot. Although this suggested a hypothesis which ascribes the long word-association latencies of young children to age-associated differences in EEG period of the left hemisphere, evidence was inconclusive.     

脑外伤及胚脑移植患者脑电地形图观察

目的：探讨脑电地形图在脑外伤和胚脑移植病人临床价值。方法：应用NDC-200型脑电地形图仪对临床颅脑外伤患者及胚脑移植患者进行脑电信号检测和脑电功率谱分析。结果：脑外伤患者损伤侧病理性δ波和θ波的绝对功率值和相对功率值均明显地高于健侧和对照组；但经胚脑移植后，随着临床症状的改善，上述现象明显恢复并与正常对照组接近。结合在鼠脑额叶皮层损伤后进行胚脑移植的脑电地形图资料及形态学观察证实脑电地形图有改善的大鼠均有移植区存活良好的佐证。结论：脑电地形图能准确地定性，定量和定位反映脑功能状态的改变，并且可作为中枢神经系统再生功能测试手段之一。     

Using Transfer Learning of Convolutional Neural Network on Neck Radiographs to Identify Acute Epiglottitis

Journal of Digital Imaging - Acute epiglottitis (AE) is a life-threatening condition and needs to be recognized timely. Diagnosis of AE with a lateral neck radiograph yields poor reliability and...     

Effects of CPAP-Therapy on Brain Electrical Activity in Obstructive Sleep Apneic Patients: A Combined EEG Study Using LORETA and Omega Complexity : Reversible Alterations of Brain Activity in OSAS

Effects of initiation of continuous positive airway pressure (CPAP) therapy on EEG background activity were investigated in patients with obstructive sleep apnea syndrome (OSAS, N?=?25) to test possible reversibility of alterations of brain electrical activity caused by chronic hypoxia. Normal control group (N?=?14) was also examined. Two EEG examinations were done in each groups: at night and in the next morning. Global and regional (left vs. right, anterior vs. posterior) measures of spatial complexity (Omega complexity) were used to characterize the degree of spatial synchrony of EEG. Low resolution electromagnetic tomography (LORETA) was used to localize generators of EEG activity in separate frequency bands. Before CPAP-treatment, a significantly lower Omega complexity was found globally and over the right hemisphere. Due to CPAP-treatment, these significant differences vanished. Significantly decreased Omega complexity was found in the anterior region after treatment. LORETA showed a decreased activity in all of the beta bands after therapy in the right hippocampus, premotor and temporo-parietal cortex, and bilaterally in the precuneus, paracentral and posterior cingulate cortex. No significant changes were seen in control group. Comparing controls and patients before sleep, an increased alpha2 band activity was seen bilaterally in the precuneus, paracentral and posterior cingulate cortex, while in the morning an increased beta3 band activity in the left precentral and bilateral premotor cortex and a decreased delta band activity in the right temporo-parietal cortex and insula were observed. These findings indicate that effect of sleep on EEG background activity is different in OSAS patients and normal controls. In OSAS patients, significant changes lead to a more normal EEG after a night under CPAP-treatment. Compensatory alterations of brain electrical activity in regions associated with influencing sympathetic outflow, visuospatial abilities, long-term memory and motor performances caused by chronic hypoxia could be reversed by CPAP-therapy.     

生物电阻抗脑功能成像研究现状

生物电阻抗成像技术在脑功能和脑疾病检测与监护中具有潜在的应用价值,并且具有无创伤、功能性、价格低、操作简便等优点,是目前生物医学工程的研究热点。本文主要介绍了生物电阻抗成像技术在脑功能和脑疾病成像的研究现状,并着重讨论了EIT(electrical impedance tomography,生物电阻抗断层成像)、MIT(magnetic induction tomography,磁感应电阻抗成像)、MREIT(magnetic resonanceelectrical impedance tomography,磁共振电阻抗成像)、MAT-MI(magnetoacoustic tomography with magneticinduction,磁感应磁声成像)技术在成像过程中的区别及今后有待近一步解决的理论与技术难题。     

神经元电活动模型的仿真研究

神经网络的宏观活动是由多个神经元电活动的叠加决定,神经元电活动的研究对深入理解神经网络工作机制和生理行为具有重要意义。本文采用Chay模型,对神经元电活动进行Simulink仿真研究,通过施加包括恒值、阶跃、脉冲、随机噪声等不同类型的输入,观察系统的输出响应。仿真结果符合通常的生理认识,有助于加深对神经元电活动和神经网络生理机制的理解。     

基于DenseMedic网络的脑皮层下结构的语义分割

脑皮层下结构分割问题是神经科及其他相关疾病计算机辅助诊断和治疗的基础。通过分割和分析核磁共振图像中的脑结构,可以对自闭症谱系障碍、脑卒中、脑肿瘤等疾病进行早期诊断和治疗。为解决精准脑结构分割的问题,基于深度学习基本理论,提出一种DenseMedic网络的核磁共振图像脑皮层下结构的分割算法。首先,OreoDown方法通过较早地增大卷积核的步长增大特征感受野的增长速度,并使用不变尺寸的卷积层夹心式地恢复网络深度,使速度的增加带来有效的感受野增加;其次,DenseMedic使用DenseNet的思想实例化OreoDown框架,通过密集连接的特征提取操作来获取多尺度的上下文信息;最后,在各层中使用混合空洞卷积进一步扩大感受野,解决特征感知过于粗糙的问题。采用Dice相似度系数(DSC)、交并比(IoU)、95% Hausdorff表面距离(HSD95)和平均表面距离(ASD) 4个指标,评价神经网络的分割性能。在公开的IBSR数据集的18例图像上进行实验,算法的4个指标分别达到89.2%、80.7%、1.982和0.882;在公开的MBBrainS18数据集的7例图像上的实验显示,算法的4个指标分别达到88.7%、79.8%、1.249和0.570。实验表明,所提出的算法使脑结构的分割结果与真实结构在区域上有更多的重叠, 在轮廓上更加相似,可以更好地完成各个脑皮层下结构的分割。在临床应用中,对脑皮层下结构的精准分割将有助于准确测量相关疾病诊断的关键指标,并实现快速的计算机辅助治疗。     

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。     

Machine Learning Approaches to Identify Factors Associated with Women's Vasomotor Symptoms Using General Hospital Data

BackgroundTo analyze the factors associated with women''s vasomotor symptoms (VMS) using machine learning.MethodsData on 3,298 women, aged 40–80 years, who attended their general health check-up from January 2010 to December 2012 were obtained from Korea University Anam Hospital in Seoul, Korea. Five machine learning methods were applied and compared for the prediction of VMS, measured by the Menopause Rating Scale. Variable importance, the effect of a variable on model performance, was used for identifying the major factors associated with VMS.ResultsIn terms of the mean squared error, the random forest (0.9326) was much better than linear regression (12.4856) and artificial neural networks with one, two, and three hidden layers (1.5576, 1.5184, and 1.5833, respectively). Based on the variable importance from the random forest, the most important factors associated with VMS were age, menopause age, thyroid-stimulating hormone, and monocyte, triglyceride, gamma glutamyl transferase, blood urea nitrogen, cancer antigen 19-9, C-reactive protein, and low-density lipoprotein cholesterol levels. Indeed, the following variables were ranked within the top 20 in terms of variable importance: cancer antigen 125, total cholesterol, insulin, free thyroxine, forced vital capacity, alanine aminotransferase, forced expired volume in 1 second, height, homeostatic model assessment for insulin resistance, and carcinoembryonic antigen.ConclusionMachine learning provides an invaluable decision support system for the prediction of VMS. For managing VMS, comprehensive consideration is needed regarding thyroid function, lipid profile, liver function, inflammation markers, insulin resistance, monocyte count, cancer antigens, and lung function.     

Quantitative Panoramic Imaging of Epicardial Electrical Activity

Fluorescent imaging with voltage- and/or calcium-sensitive dyes has revolutionized cardiac physiology research. Here we present improved panoramic imaging for optically mapping electrical activity from the entire epicardium of the Langendorff-perfused rabbit heart. Combined with reconstruction of the 3D heart surface, the functional data can be conveniently visualized on the realistic heart geometry. Methods to quantify the panoramic data set are introduced by first describing a simple approach to mesh the heart in regular grid form. The regular grid mesh provides substrate for easy translation of previously available non-linear dynamics methods for 2D array data. It also simplifies the unwrapping of curved three-dimensional surface to 2D surface for global epicardial visualization of the functional data. The translated quantification methods include activation maps (isochrones), phase maps, phase singularity, and electric stimulus-induced virtual electrode polarization (VEP) maps. We also adapt a method to calculate the conduction velocities on the global epicardial surface by taking the curvature of the heart surface into account.