脑机融合系统综述

脑机接口是生物脑与电脑或机器之间的一种直接连接通路。脑机融合计算系统是一种基于脑机接口技术,综合利用生物智能和机器智能的新型智能融合系统,其在医疗康复、生活娱乐和军事侦查等方面具有巨大的应用开发潜力。首先从信息传输的角度简述由脑机接口到脑机融合的发展趋势;其次重点阐述脑机融合系统的概念及其研究所面临的挑战,并分三个层次介绍当前若干典型相关工作;最后介绍吴朝晖课题组在脑机融合计算系统方面的相关工作。     

基于混沌优化算法的MUSIC脑磁图源定位方法

如何利用实验测得的脑磁图数据准确定位脑磁图源的真实活动位置是脑功能研究和临床应用中的一个关键问题.在脑磁活动源定位问题中,多信号分类算法是被广泛研究和采用的一类方法.为了克服多信号分类算法及其改进算法--递归多信号分类算法全局扫描时速度太慢的缺点,提出了一种基于混沌优化算法的脑磁图源定位新方法.该方法利用混沌运动遍历性的特点估计目标函数的全局最大值,进行初步的脑磁图源定位;然后,在小范围内结合网格的方法,进一步进行精确的定位.实验结果表明,此方法可实现多个脑磁图源的定位,并且定位速度大大加快,同时又能达到所要求的定位精度.     

基于粒子群优化算法的脑磁图源定位

脑磁图作为一种新型的脑探测技术,具有较高定位精度和毫秒级时间分辨率的特点。快速准确地利用脑磁图技术对三维空间中的脑神经活动源进行定位,对于脑功能研究和医学临床应用都具有重要的应用价值。可是,目前的脑磁图源定位广泛采用了多信号分类方法,它要求对三维大脑空间进行全局扫描,需要大量的计算,存在速度慢的缺点。针对这一问题,提出了一种基于粒子群优化算法的脑磁图源定位方法。先利用粒子群优化算法全局搜索能力强的特点寻找出目标函数的全局最优值,进行初步的脑磁图源定位;然后,再在小范围内进行小网格的搜索,进一步实现精确的定位。实验结果表明,基于粒子群优化算法的脑磁图源定位能够很好地解决上述问题,具有计算速度快、定位精度高的特点。     

应用MRI预扫描定位提高大鼠脑立体定位术的准确性

目的评价MRI预扫描方法在鼠脑穿刺定位准确性上的作用与价值。材料与方法选取健康雄性SD大鼠18只,随机分为2组,分别为MRI预扫描定位组（9只）,在MR图像指导下进行穿刺注射;以及经典穿刺组（9只）,不采用MR影像学检测定位,严格按照脑立体定位图谱进行穿刺注射。穿刺以通过苍白球中心的鼠脑切面中尾状核区为靶目标,穿刺后采用MRI影像学方法确定穿刺点位置,比较MRI预扫描定位穿刺与经典立体定位穿刺的准确度。结果 MRI预扫描定位组穿刺准确率为88.89%,经典穿刺组穿刺准确率为66.67%;两种方法的穿刺定位差异有显著性（P〈0.05）,MRI预扫描组的穿刺定位准确度明显高于经典穿刺组。结论 MRI预扫描可显著提高鼠脑立体定位穿刺的准确度,是进行立体定位精细穿刺的必要操作。     

脑磁图的临床应用研究

脑磁图(magnetoencephalogragphy,MEG),是一种通过测量脑磁场信号,对脑功能区进行定位及评价其状态的新技术,具有对人体无侵袭、无损伤等特点,目前已在人脑的功能研究和临床上进行应用。     

2022年脑科学与类脑智能发展态势

脑科学是理解人和自然的“终极疆域”,现已成为重要的科学和技术前沿领域之一。该文主要从研究计划、研究进展、产品研发与产业发展的视角分析2022年脑科学与类脑智能领域的进展,并对未来发展趋势加以展望。2022年,美国、中国等国家/地区的脑计划取得较大进展;在脑图谱绘制、脑发育与脑认知功能解析、脑疾病机制探索及类脑智能技术与产品开发方面取得重要研究突破;脑疾病药物研发管线丰富,将推动相关产业快速发展。未来,借助各类新技术,研究人员将在多尺度解析脑认知功能,识别其中的功能障碍,开发出多种有效的脑疾病治疗药物;脑科学与人工智能等领域相互借鉴,推动类脑智能领域快速发展并广泛应用;数据治理和伦理安全的突破有助于脑科学与类脑智能研究的良性发展。     

基于混沌优化算法的多信号分类脑磁图源定位方法

如何利用实验测得的脑磁图数据准确定位脑磁图源的真实活动位置是脑功能研究和临床应用中的一个关键问题.在脑磁活动源定位问题中,多信号分类算法是被广泛研究和采用的一类方法.为了克服多信号分类算法及其改进算法--递归多信号分类算法全局扫描时速度太慢的缺点,提出了一种基于混沌优化算法的脑磁图源定位新方法.该方法利用混沌运动遍历性的特点估计目标函数的全局最大值,进行初步的脑磁图源定位;然后,在小范围内结合网格的方法,进一步进行精确的定位.实验结果表明,此方法可实现多个脑磁图源的定位,并且定位速度大大加快,同时又能达到所要求的定位精度.     

脑微循环

脑毛细血管形态结构不规则、弯曲度高、三维吻合网不对称、血流速度较快、生理状态下可见“摆流”。缺氧时脑微血管直径增大、血流速度加快、血管通透性增加。脑微循环的调节较复杂,有神经因素、化学因素;血管活性肠肽(VIP)、前列腺素(PG)、P物质(SP)也参与脑微循环调节。     

第一届脑功能与脑疾病学术研讨会通知

<正>2010年10月24日-27日,北京由中国科学院生物物理研究所脑与认知科学国家重点实验室、中国生物物理学会神经生物物理与神经信息学专业委员会和中国科学院脑功能与脑疾病重点实验室(中国科技大学)联合主办的"第一届脑功能与脑疾病学术研讨会"将于2010年在北京召开。     

鸡胚完整脑的光子发射和光激发光研究

利用自制的单光子记录系统,对离体的浸于DMEM培养液中的鸡胚的完整脑所进行的光子发射测量显示出整脑与培养液相比有光子发射.完整脑的光子发射强度与胚龄,鸡胚的健康状况和离体后脑组织的新鲜程度有关.在对完整脑的光激发光测量中观察到一种短寿命的延迟发光,它的衰减过程不服从指数衰减规律而表现出双曲线衰减行为.从生物光子发射归因于生物体内的非定位的相干性电磁场及Frohlish的生命系统中存在着长距离的相干性的理论,讨论了利用生物光子发射研究细胞间通讯、生物的调节及生物与环境关系的意义,以及所检测的光子发射与生物系统自身的相干性电磁场的关系,并提出应从环境对生物系统自身场的影响来理解所测的生物光子发射.     

脉冲电磁波对球形大脑作用的理论计算

建立了脑球体模型,赋于脑壳与内部组织不同的电参数,应用时域有限差分法（ＦＤＴＤ）计算了在脉冲电磁波辐射下脑内各点电场的瞬时波形及相应的比吸收率ＳＡＲ。计算结果表明,脉冲电磁波对大脑的瞬态作用时间比脉冲宽度要长,且各点波形不尽相同,但在脑中心有最大的ＳＡＲ,对此讨论了其安全性     

基于小波变换的单次诱发电位信号时频分析

比较小波变换和平均叠加两种方法提取“模拟自然阅读”刺激模式下的诱发脑电信号,分析其时频特性,并进行脑功能源分布定位分析。结果显示,采用平均叠加法来提取和分析诱发电位信号,损失了某些重要的诱发电位成分,且其功能源分布定位反映的只是等效功能源的静态过程;而使用小波变换和脑功能源定位来提取和分析单次诱发电位信号,既能观察到丰富的诱发电位成分,又能反映脑功能源的实时动态活动过程。这表明,小波变换下的时频分析是脑电信号处理的一种可行的新方法。     

Effect of extremely low frequency electromagnetic field on brain histopathology of Caspian Sea Cyprinus carpio

There is limited research on the effect of electromagnetic field on aquatic organisms, especially freshwater fish species. This study was conducted to evaluate the effect of extremely low frequency electromagnetic field (ELF-EMF) (50 Hz) exposure on brain histopathology of Cyprinus carpio, one of the important species of Caspian Sea with significant economic value. A total of 200 healthy fish were used in this study. They were classified randomly in two groups: sham-exposed group and experimental group, which were exposed to five different magnetic field intensities (0.1, 1, 3, 5, and 7 mT) at two different exposure times (0.5 and 1 h). Histologic results indicate that exposure of C. carpio to artificial ELF-EMF caused severe histopathological changes in the brain at field intensities ≥3 mT leading to brain necrosis. Field intensity and duration of exposure were key parameters in induction of lesion in the brain. Further studies are needed to elucidate exact mechanism of EMF exposure on the brain.     

Effects of sinusoidal electromagnetic fields on histopathology and structures of brains of preincubated white leghorn chicken embryos

There are several reports indicating linkages between exposures to 50–60 Hz electromagnetic fields and abnormalities in the early stages of chicken embryonic development. Based on our previous published research carried out at the Department of Animal Sciences, Faculty of Biological Sciences, Shahid Beheshti University, effects of sinusoidal electromagnetic fields on histopathology and structures of brains of preincubated white leghorn hen eggs were investigated. Three hundred healthy fresh fertilized eggs (55–65 gr) were divided into three groups of experimental (n = 50), control (n = 75), and sham (n = 75). Experimental eggs (inside the coil) were exposed to 3 different intensities of 1.33, 2.66, and 7.32 mT and sham groups were located inside the same coil with no exposure, for 24 h before incubation. Control, sham, and experimental groups were all incubated in an incubator (38 ± 0.5^°C, 60% humidity) for 14 days. 14-day old chicken embryos were removed by C-sections, and the brains of all embryos of all groups were fixed in formalin(10%), stained with H&E and TUNEL assay, for studying the histopatholog and process of apoptosis. The brains of other embryos were prepared for Scanning Electeron Microscope. Results showed electromagnetic fields have toxic effects on brain cells by increasing the number of apoptotic cells and degeneration of brains' tissues of exposed chicken embryos. These findings suggest that the electromagnetic fields induce brain damages at different levels.     

脑源定位技术的精度评估及其在实际中的应用

脑源定位技术旨在通过头皮表面的脑电、脑磁信号来识别大脑内的神经活动源，是研究大脑皮层神经活动、认知过程和病理功能的基础。其毫秒级的时间分辨率可以有效弥补功能核磁共振在低时间分辨率方面的不足。然而，理论分析层面中逆问题的不适定性，以及实践操作层面上不同的记录方式、电极数量和头模型构建等过程带来的误差，给脑源定位的准确性带来极大挑战，也在一定程度上限制了脑源定位方法在神经科学和心理学研究以及临床诊断治疗中的实际应用。因此，理论分析和实践操作层面中的精度评估在脑源定位方法的实际使用中至关重要。针对以上问题，本文在对现有脑源定位方法介绍的基础上，着重分析了脑源定位技术的精度评估方法以及其在基础研究和临床诊断治疗中的实际应用。具体地，本文在理论分析中总结了基于空间分辨率、基于点扩散以及串扰函数的评估方法对于不同脑源定位方法中源的重叠程度和其他源对目标源的影响；在实践操作中介绍了记录方式、电极数量和密度、头部容积传导模型等因素对源定位精度的影响；进一步介绍了脑源定位技术在时频分析、连通性分析中的应用，以及其在临床中的应用，包括癫痫、注意缺陷与多动障碍等脑部疾病。     

Immunohistochemical detection of dysbindin at the astroglial endfeet around the capillaries of mouse brain

Dysbindin was first identified by the yeast two hybrid assay as a binding partner of dystrobrevin which is a cytoplasmic member of dystrophin glycoprotein complex. Immunolocalization of dystrobrevin in the astrocyte endfeet and endothelial cells in the rat cerebellum was reported. Therefore, we were interested in the expression and localization of dystrobrevin binding protein dysbindin in the mouse brain capillary wall and its surrounding astroglial endfeet. We examined whether the dysbindin expression is present in astroglial endfeet and/or capillary endothelial cells at light and electron microscopic levels. Using brain samples from five normal mice (C57BL/6ScSn), we prepared the anti-dysbindin antibody stained brain samples with immunoperoxidase method at light microscopic level and with immunogold method at ultrastructural level. Immunohistochemistry showed that dysbindin was located in the brain capillary at light microscopic level. Immunogold electron microscopy revealed that dysbindin signal was observed at the inside surface of plasma membrane of glial endfeet which surrounded the brain capillary endothelial cells and pericytes.     

A truffle in the mouth is worth two in the bush: odor localization in the human brain

It is widely thought that locating the source of a smell is an ability best left to nonhuman members of the animal kingdom. In this issue of Neuron, two complementary articles highlight the neural mechanisms underlying the localization of an odor, either to the left or right side of the nose (Porter et al.) or to the inside or outside of the mouth (Small et al.). Together, these studies validate the idea that the human brain is equipped with the apparatus necessary to pinpoint the location of an odor source.     

Dipole Source Localization of Mouse Electroencephalogram Using the Fieldtrip Toolbox

The mouse model is an important research tool in neurosciences to examine brain function and diseases with genetic perturbation in different brain regions. However, the limited techniques to map activated brain regions under specific experimental manipulations has been a drawback of the mouse model compared to human functional brain mapping. Here, we present a functional brain mapping method for fast and robust in vivo brain mapping of the mouse brain. The method is based on the acquisition of high density electroencephalography (EEG) with a microarray and EEG source estimation to localize the electrophysiological origins. We adapted the Fieldtrip toolbox for the source estimation, taking advantage of its software openness and flexibility in modeling the EEG volume conduction. Three source estimation techniques were compared: Distribution source modeling with minimum-norm estimation (MNE), scanning with multiple signal classification (MUSIC), and single-dipole fitting. Known sources to evaluate the performance of the localization methods were provided using optogenetic tools. The accuracy was quantified based on the receiver operating characteristic (ROC) analysis. The mean detection accuracy was high, with a false positive rate less than 1.3% and 7% at the sensitivity of 90% plotted with the MNE and MUSIC algorithms, respectively. The mean center-to-center distance was less than 1.2 mm in single dipole fitting algorithm. Mouse microarray EEG source localization using microarray allows a reliable method for functional brain mapping in awake mouse opening an access to cross-species study with human brain.     

Radiofrequency electromagnetic radiation exposure inside the metro tube infrastructure in Warszawa

Abstract

Antennas from various wireless communications systems [e.g. mobile phones base transceiver stations (BTS) and handsets used by passengers, public Internet access, staff radiophone transmitters used between engine-drivers and traffic operators] emitting radiofrequency electromagnetic radiation (RF-EMR) are used inside underground metro public transportation. Frequency-selective exposimetric investigations of RF-EMR exposure inside the metro infrastructure in Warsaw (inside metro cars passing between stations and on platforms) were performed. The statistical parameters of exposure to the E-field were analyzed for each frequency range and for a total value (representing the wide-band result of measurements of complex exposure). The recorded exposimetric profiles showed the dominant RF-EMR sources: handsets and BTS of mobile communication systems (GSM 900 and UMTS 2100) and local wireless Internet access (WiFi 2G). Investigations showed that the GSM 900 system is the dominant source of exposure – BTS (incessantly active) on platforms, and handsets – used by passengers present nearby during the tube drive. The recorded E-field varies between sources (for BTS were: medians – 0.22?V/m and 75th percentile – 0.37?V/m; and for handsets: medians – 0.28?V/m and 75th percentile – 0.47?V/m). Maximum levels (peaks) of exposure recorded from mobile handsets exceeded 10?V/m (upper limit of used exposimeters). Broadband measurements of E-field, including the dominant signal emitted by staff radiophones (151?MHz), showed that the level of this exposure of engine-drivers does not exceed 2.5?V/m.     

Low-Frequency Magnetic Fields in Cars and Office Premises and the Geomagnetic Field Variations

In this study, we measured and analyzed the spectral characteristics of a low-frequency magnetic field (MF) inside several gasoline-powered cars while driving on busy city roads. The spectra obtained upon measurements in the interior of the cars are compared with those measured in office locations at different times of the day and with different disturbances of the geomagnetic field (k-index of disturbance 2–8). The power spectral density of the electromagnetic field in cars moving on busy roads in the frequency range of 10⁻³–10² Hz is one to three orders of magnitude higher than that in urban offices. This raises a question regarding the possible influence of these MFs on the psychophysiological state of drivers. In turn, in the daytime, the MF power in the range from 10⁻³ to 1 Hz inside the locations is three times higher compared with the power of a strong geomagnetic storm. Despite such an overwhelming magnetic background, geomagnetic storms affect various organisms. The nonspecific effect of magnetic storms is supposed to be associated with relatively long (lasting several hours or more [frequency range of 10⁻⁴−10⁻⁵ Hz]) periods of enhancement or weakening of the local geomagnetic field. In this range, especially at night, the power spectral density of geomagnetic disturbances is comparable to and can even exceed the power density of urban MFs. © 2020 Bioelectromagnetics Society.