结合局部一致性和低频振幅探究躯体症状障碍患者大脑自发性活动的改变

躯体症状障碍（somatic symptom disorder,SSD）是一种常见的医学疾病,致病原因涉及生物学、心理学及社会因素.目前关于SSD的神经机制知之甚少.本研究通过静息态功能磁共振成像（functional magnetic resonance imaging,fMRI）,结合低频振幅（amplitudes of low-frequency fluctuation,ALFF）和局部一致性（regional homogeneity,ReHo）分析探究45位SSD患者和43位健康对照自发性脑活动特征的区别.结果发现：与对照组相比,SSD患者右侧扣带回中部的ReHo值显著升高,而右侧楔前叶、左侧颞下回延伸到左侧颞中回和左侧海马旁回、右侧脑桥的ReHo值显著降低.同时,SSD患者扣带回中部延伸至左侧额中回、右侧脑岛延伸至右侧额下回、左侧额中回延伸至左侧前扣带回的ALFF值均显著升高.这些脑区的脑功能与自我加工、情绪处理、身体知觉等有关,与SSD发病机制有重要联系.     

一种新颖的表面光波导型原子(或分子)分束器

提出了一种采用二元π位相板与柱面透镜组合而构成表面光波导型原子（或分子）分束器及其Mach-Zehnder干涉仪与X-分束器列阵的新方案，介绍了本方案的物理思想与基本原理，导出了光强分布、强度梯度、分束距离和分束路径的宽度与光学系统参数间的解析关系，并分析和讨论了本方案的潜在应用及其可行性. 研究表明，本方案设计新颖、光路简单，便于与其他元件组合构成具有表面微结构的集成原子（或分子）光学元器件及其全光型原子（或分子）芯片. 关键词： 原子（或分子）光波导 原子（或分子）分束器 原子（或分子）芯片 二元π位相板     

基于哈德曼编码的新型高分辨定域谱

核磁共振（NMR）技术作为一种非植入无损伤的检测技术，已经广泛应用于化学、生物和医学等领域.本文基于哈德曼（Hadamard）编码的分子间单量子相干（iSQC）技术提出了一种新的序列，首先从理论上对该序列进行了简要的分析并阐明其原理，然后用套管模型实验和脑模型实验验证该序列在不均匀磁场下准确定域和快速获取高分辨谱的能力.实验表明，该序列在不均匀磁场下可以快速获取高分辨定域谱，同时抑制溶剂峰信号，具备一定的应用价值.     

氨基葡萄糖及羧甲基氨基葡萄糖与铁(Ⅱ)、锌(Ⅱ)、钴(Ⅱ)、铜(Ⅱ)配合物的光谱特征

本文研究了氨基葡萄糖及羧甲基氨基葡萄糖分别与铁（Ⅱ）、锌（Ⅱ）、钴（Ⅱ）、铜（Ⅱ）形成配合物的UV，IR和^1H-NMR光谱特征。配合物紫外的λmax发生了明显紫移；在IR谱中，配合物的面外振动峰655cm^-1较未配位的氨基葡萄糖中的面外振动峰670cm^-1低，且在990cm^-1附近出现新的吸收峰；在^1H-NMR谱中，配合物C3上羟基中的质子化学位移较未配位的均移向高场，氨基上质子的化学位移较未配位的也移向高场，其他碳上羟基中的质子化学位移值不变，从而初步证实了配合物中的氨－金属（N－M）键的形成。本文还研究了羧甲基氨基葡萄糖及其与铁（Ⅱ）、钴（Ⅱ）、铜（Ⅱ）配合物的合成。其配合物的IR谱线较未配位的IR谱线并没增多，指出这种反常现象是糖环的刚性所致。它们的IR和UV光谱均证实了分子中不存在游离的羰基峰，并证实了它们分子中内盐的存在，配合物的IR谱中出现新的一组吸收峰：433.1和408.9cm^-1(O-Fe)，507．1和495．0cm^-1（O－Co),403.1和389.0cm^-1(O-Cu)，证实了配合物中的氧－金属键（O－M）的形成。     

数据采集方案对神经扩散模型影响的评估

基于单次数据采集的多种扩散模型联合应用已逐渐成为临床研究的热点,本研究比较了三种采集方案对于神经扩散模型定量计算的影响,包括Q空间笛卡尔网格（QGrid）、多壳层异向（Free）和多壳层同向（MDDW）采集方案,涉及的扩散模型包含扩散张量成像（DTI）;扩散峰度成像（DKI）;神经突方向分散度和密度成像（NODDI）;平均表观传播（MAP）模型.结果表明DTI和DKI模型对采集方案相对不敏感,而NODDI和MAP对采集方案和最大b值的设置相对较敏感,并且QGrid和Free方案一致性较高,因此在大样本和多中心研究中需要考虑采集方案的选择.此外,考虑到QGrid和Free方案分别在结合更多扩散模型和神经纤维束成像应用上更具优势,因此推荐使用.     

铕和铽对四（3,4-亚甲二氧基苯基）卟啉的荧光猝灭

通过荧光光谱法研究了铕（Ⅲ）、铽（Ⅲ）两种稀土离子对四（3,4-亚甲二氧基苯基）卟啉（TMPP）荧光强度的影响.在中性介质中,铕（Ⅲ）和铽（Ⅲ）与TMPP相互作用使TMPP的荧光猝灭.实验表明：以DMF为溶剂、420 nm为最大激发波长、655nm为最大发射波长时,TMPP的荧光强度和稀土离子对其荧光猝灭均达到最大值.     

三原子分子的U（5）模型

对于线型三原子分子，其振转谱利用Ｕ（５）群的不可约表示进行分类。动力学对称性Ｕ（５）Ｏ（５）Ｏ（３）被研究，并用来讨论了ＨＣＮ分子的能谱，计算结果与实验结果能较好地吻合。     

基于PLC的PMD补偿器中PDL效应的分析

应用穆勒（Müller）矩阵对硅基平面光波导线路（Planar lightwave circuit PLC）补偿器中PDL对差分群时延(Differential group delay DGD)分布的影响进行了分析，在不同的PDL值下对各种不同级次的PLC单元级联情况的DGD值分布进行了讨论，并与Maxwell分布进行了比较，得到了在特定PDL值情况下最为优化的PLC级次.     

高功率垂直腔面发射半导体激光器优化设计研究

与传统的端发射半导体激光器相比，垂直腔面发射半导体激光器（VCSEL）具有可单模输出，光束对称性好，可被高度聚焦，进入光纤的耦合效率极高和有利于大规模二维列阵等优 点.为了得到高功率的激光输出，除了要增大VCSEL的发射面积之外，关键的是要选择适 当的量子阱层数、有源区电流密度的均匀分布和良好的热管理等.本文详细研究和分析了高功率VCSEL有源区量子阱层数，有源区直径，材料的热导和电阻，电极间距等对VCSEL 器件性能的影响.通过优化参数，进行最佳设计，研制出了980 nm In0.2Ga0.8As/Ga 关键词： 垂直腔面发射激光器（VCSEL） 量子阱 高功率     

铬蓝黑R负载活性炭对Cr（Ⅲ）和Pb（Ⅱ）的吸附性能

研究了新型吸附材料铬蓝黑R（钙试剂）负载改性的活性炭对样品中Cr（Ⅲ）和Pb（Ⅱ）的固相萃取（SPE）并用电感耦合等离子体-原子发射光谱法（ICP-AES）进行检测.优化了pH值、吸附剂用量、流速等条件以达到定量吸附（≥95％）,同时研究了洗脱剂的最佳洗脱条件以及共存离子干扰等问题.本法测定Cr（Ⅲ）和Pb（Ⅱ）的检出限分别为0.91ng·mL-1和0.65ng·mL-1,将其应用于土壤沉积物、猪肝、黄河水中的Cr（Ⅲ）和Pb（Ⅱ）含量的测定,加标回收率在98％-101％之间;用于测定标准物质中Cr（Ⅲ）和Pb（Ⅱ）的含量,结果与标准物参照值一致.     

Real-time MR artifacts filtering during continuous EEG/fMRI acquisition

The purpose of this study was the development of a real-time filtering procedure of MRI artifacts in order to monitor the EEG activity during continuous EEG/fMRI acquisition. The development of a combined EEG and fMRI technique has increased in the past few years. Preliminary “spike-triggered” applications have been possible because in this method, EEG knowledge was only necessary to identify a trigger signal to start a delayed fMRI acquisition. In this way, the two methods were used together but in an interleaved manner. In real simultaneous applications, like event-related fMRI study, artifacts induced by MRI events on EEG traces represent a substantial obstacle for a right analysis. Up until now, the methods proposed to solve this problem are mainly based on procedures to remove post-processing artifacts without the possibility to control electrophysiological behavior of the patient during fMRI scan. Moreover, these methods are not characterized by a strong “prior knowledge” of the artifact, which is an imperative condition to avoid any loss of information on the physiological signals recovered after filtering. In this work, we present a new method to perform simultaneous EEG/fMRI study with real-time artifacts filtering characterized by a procedure based on a preliminary analytical study of EPI sequence parameters-related EEG-artifact shapes. Standard EEG equipment was modified in order to work properly during ultra-fast MRI acquisitions. Changes included: high-performance acquisition device; electrodes/cap/wires/cables materials and geometric design; shielding box for EEG signal receiver; optical fiber link; and software. The effects of the RF pulse and time-varying magnetic fields were minimized by using a correct head cap wires-locked environment montage and then removed during EEG/fMRI acquisition with a subtraction algorithm that takes in account the most significant EPI sequence parameters. The on-line method also allows a further post-processing utilization.     

Performance evaluation of nonnegative matrix factorization algorithms to estimate task-related neuronal activities from fMRI data

Nonnegative matrix factorization (NMF) is a blind source separation (BSS) algorithm which is based on the distinct constraint of nonnegativity of the estimated parameters as well as on the measured data. In this study, according to the potential feasibility of NMF for fMRI data, the four most popular NMF algorithms, corresponding to the following two types of (1) least-squares based update [i.e., alternating least-squares NMF (ALSNMF) and projected gradient descent NMF] and (2) multiplicative update (i.e., NMF based on Euclidean distance and NMF based on divergence cost function), were investigated by using them to estimate task-related neuronal activities. These algorithms were applied firstly to individual data from a single subject and, subsequently, to group data sets from multiple subjects. On the single-subject level, although all four algorithms detected task-related activation from simulated data, the performance of multiplicative update NMFs was significantly deteriorated when evaluated using visuomotor task fMRI data, for which they failed in estimating any task-related neuronal activities. In group-level analysis on both simulated data and real fMRI data, ALSNMF outperformed the other three algorithms. The presented findings may suggest that ALSNMF appears to be the most promising option among the tested NMF algorithms to extract task-related neuronal activities from fMRI data.     

A preliminary study of functional abnormalities in aMCI subjects during different episodic memory tasks

Functional magnetic resonance imaging (fMRI) is an important imaging modality to understand the neurodegenerative course of mild cognitive impairment (MCI) and early Alzheimer's disease (AD), because the memory dysfunction may occur before structural degeneration is obvious. In this research, we investigated the functional abnormalities of subjects with amnestic MCI (aMCI) using three episodic memory paradigms that are relevant to different memory domains in both encoding and recognition phases. Both whole-brain analysis and region-of-interest (ROI) analysis of the medial temporal lobes (MTL), which are central to the memory formation and retrieval, were used to compare the efficiency of the different memory paradigms and the functional difference between aMCI subjects and normal control subjects. We also investigated the impact of using different functional activation measurements in ROI analysis. This pilot study could facilitate the use of fMRI activations in the MTL as a marker for early detection and monitoring progression of AD.     

BOLD functional MRI in disease and pharmacological studies: room for improvement?

In the past decade the use of blood oxygen level-dependent (BOLD) fMRI to investigate the effect of diseases and pharmacological agents on brain activity has increased greatly. BOLD fMRI does not measure neural activity directly, but relies on a cascade of physiological events linking neural activity to the generation of MRI signal. However, most of the disease and pharmacological studies performed so far have interpreted changes in BOLD fMRI as "brain activation," ignoring the potential confounds that can arise through drug- or disease-induced modulation of events downstream of the neural activity. This issue is especially serious in diseases (like multiple sclerosis, brain tumours and stroke) and drugs (like anaesthetics or those with a vascular action) that are known to influence these physiological events. Here we provide evidence that, to extract meaningful information on brain activity in patient and pharmacological BOLD fMRI studies, it is important to identify, characterise and possibly correct these influences that potentially confound the results. We suggest a series of experimental measures to improve the interpretability of BOLD fMRI studies. We have ranked these according to their potential information and current practical feasibility. First-line, necessary improvements consist of (1) the inclusion of one or more control tasks, and (2) the recording of physiological parameters during scanning and subsequent correction of possible between-group differences. Second-line, highly recommended important aim to make the results of a patient or drug BOLD study more interpretable and include the assessment of (1) baseline brain perfusion, (2) vascular reactivity, (3) the inclusion of stimulus-related perfusion fMRI and (4) the recording of electrophysiological responses to the stimulus of interest. Finally, third-line, desirable improvements consist of the inclusion of (1) simultaneous EEG-fMRI, (2) cerebral blood volume and (3) rate of metabolic oxygen consumption measurements and, when relevant, (4) animal studies investigating signalling between neural cells and blood vessels.     

EEG quality during simultaneous functional MRI of interictal epileptiform discharges

This article concerns the evaluation of the quality of interictal epileptiform EEG discharges recorded throughout simultaneous echo planar imaging (EPI). BOLD (blood oxygen level dependent) functional MRI (fMRI) images were acquired continuously on a patient with intractable epilepsy. EEG was sampled simultaneously, during and after imaging, with removal of pulse and imaging artifacts by subtraction of channel-specific running averages. Contiguous EEG epochs recorded with and without fMRI (fMRI+ve vs. fMRI−ve) were next randomized and presented to two blinded observers. Epileptiform discharges were identified retrospectively, and comparison was made in terms of the number of identified events, their amplitude, and spatiotemporal distribution. A spectral analysis was also performed on the EEG. In the randomized comparison of EEG segments, 80 (fMRI+ve) vs. 69 (fMRI−ve) discharges were noted with good interobserver agreement (69%). There were no significant differences in amplitude or spatio-temporal distribution. Comparison of the events detected and measured by two expert observers demonstrated that the Interictal Epileptiform Discharge (IED) characteristics were indistinguishable with and without scanning. We review briefly the existing literature on EEG recording quality for combined EEG/fMRI.     

Transcranial direct current stimulation for the treatment of tinnitus: a review of clinical trials and mechanisms of action

Background

Tinnitus is the perception of sound in the absence of any external acoustic stimulation. Transcranial direct current stimulation (tDCS) has shown promising though heterogeneous therapeutic outcomes for tinnitus. The present study aims to review the recent advances in applications of tDCS for tinnitus treatment. In addition, the clinical efficacy and main mechanisms of action of tDCS on suppressing tinnitus are discussed.

Methods

The study was performed in accordance with the PRISMA guidelines. The databases of the PubMed (1980–2018), Embase (1980–2018), PsycINFO (1850–2018), CINAHL, Web of Science, BIOSIS Previews (1990–2018), Cambridge Scientific Abstracts (1990–2018), and google scholar (1980–2018) using the set search terms. The date of the most recent search was 20 May, 2018. The randomized controlled trials that have assessed at least one therapeutic outcome measured before and after tDCS intervention were included in the final analysis.

Results

Different tDCS protocols were used for tinnitus ranging single to repeated sessions (up to 10) consisting of daily single session of 15 to 20-min and current intensities ranging 1–2 mA. Dorsolateral prefrontal cortex (DLPFC) and auditory cortex are the main targets of stimulation. Both single and repeated sessions showed moderate to significant treatment effects on tinnitus symptoms. In addition to improvements in tinnitus symptoms, the tDCS interventions particularly bifrontal DLPFC showed beneficial outcomes on depression and anxiety comorbid with tinnitus. Heterogeneities in the type of tinnitus, tDCS devices, protocols, and site of stimulation made the systematic reviews of the literature difficult. However, the current evidence shows that tDCS can be developed as an adjunct or complementary treatment for intractable tinnitus. TDCS may be a safe and cost-effective treatment for tinnitus in the short-term application.

Conclusions

The current literature shows moderate to significant therapeutic efficacy of tDCS on tinnitus symptoms. Further randomized placebo-controlled double-blind trials with large sample sizes are needed to reach a definitive conclusion on the efficacy of tDCS for tinnitus. Future studies should further focus on developing efficient disease- and patient-specific protocols.

     

数字微镜器件动态红外场景投影技术

动态红外场景投影(DIRSP)技术是考察和评估红外成像测量跟踪系统性能指标的主要方法。本文回顾了国内外DIRSP技术的发展现状及应用,概述了几种主要的DIRSP技术及其特点。在详细介绍数字微镜器件(DMD)的工作原理及机械结构的基础上,总结了灰度等级控制的方法及其特点。通过对3种数字光处理(DLP)显示系统投影原理的对比,指出了各自的特点和应用场合。重点分析了基于DMD的DIRSP系统—微镜阵列投影系统(MAPS)的工作原理、系统结构、性能指标及技术优势,并讨论了将DMD应用于DIRSP所采用的6大关键技术。最后,结合DIRSP技术的应用背景和国内外研究现状,对下一步的研究工作做了展望。     

Steady-state activation in somatosensory cortex after changes in stimulus rate during median nerve stimulation

Passive electrical stimulation activates various human somatosensory cortical systems including the contralateral primary somatosensory area (SI), bilateral secondary somatosensory area (SII) and bilateral insula. The effect of stimulation frequency on blood oxygenation level-dependent (BOLD) activity remains unclear. We acquired 3-T functional magnetic resonance imaging (fMRI) in eight healthy volunteers during electrical median nerve stimulation at frequencies of 1, 3 and 10 Hz. During stimulation BOLD signal changes showed activation in the contralateral SI, bilateral SII and bilateral insula. Results of fMRI analysis showed that these areas were progressively active with the increase of rate of stimulation. As a major finding, the contralateral SI showed an increase of peak of BOLD activation from 1 to 3 Hz but reached a plateau during 10-Hz stimulation. Our finding is of interest for basic research and for clinical applications in subjects unable to perform cognitive tasks in the fMRI scanner.     

Functional MRI using intravascular contrast agents: detrending of the relative cerebrovascular (rCBV) time course

In pharmacological fMRI experiments in animal models, blood pool contrast agents may be used to map cerebral blood volume change as a surrogate for neural activation. When the background signal drift due to contrast agent washout is non-negligible over the duration of the signal changes of interest, time-course detrending is essential for accurate interpretation of the experiment. Detrending approaches based on estimation of the background signal from a baseline period of the time course prior to pharmacological (or functional) challenge were evaluated with the aim of identifying a robust method of estimating the contrast agent washout contribution to the background signal drift. For fMRI studies in the rat, it was found that a constrained fit of a mono-exponential washout model was more accurate than a constant background approximation and unconstrained fits for experiments investigating the functional response to rapid pharmacological challenges such as cocaine and amphetamine. Moreover, the constrained fitting approach allows shorter baseline periods than unconstrained extrapolation, reducing the required duration of the experiment.     

Dual-hemisphere tDCS facilitates greater improvements for healthy subjects' non-dominant hand compared to uni-hemisphere stimulation

Background  

Transcranial direct current stimulation (tDCS) is a non-invasive technique that has been found to modulate the excitability of neurons in the brain. The polarity of the current applied to the scalp determines the effects of tDCS on the underlying tissue: anodal tDCS increases excitability, whereas cathodal tDCS decreases excitability. Research has shown that applying anodal tDCS to the non-dominant motor cortex can improve motor performance for the non-dominant hand, presumably by means of changes in synaptic plasticity between neurons. Our previous studies also suggest that applying cathodal tDCS over the dominant motor cortex can improve performance for the non-dominant hand; this effect may result from modulating inhibitory projections (interhemispheric inhibition) between the motor cortices of the two hemispheres. We hypothesized that stimultaneously applying cathodal tDCS over the dominant motor cortex and anodal tDCS over the non-dominant motor cortex would have a greater effect on finger sequence performance for the non-dominant hand, compared to stimulating only the non-dominant motor cortex. Sixteen right-handed participants underwent three stimulation conditions: 1) dual-hemisphere – with anodal tDCS over the non-dominant motor cortex, and cathodal tDCS over the dominant motor cortex, 2) uni-hemisphere – with anodal tDCS over the non-dominant motor cortex, and 3) sham tDCS. Participants performed a finger-sequencing task with the non-dominant hand before and after each stimulation. The dependent variable was the percentage of change in performance, comparing pre- and post-tDCS scores.