Near-infrared (NIR) light has been shown to produce a range of physiological effects in humans, however, there is still no agreement on whether and how a single parameter, like the flicker frequency of NIR light, affects the brain. An 810 nm NIR LED was used as the stimulator. Fifty subjects participated in this experiment. Forty subjects were randomly divided into four groups. Each group underwent a 30-minute NIR LED radiation with four different frequencies (i.e., 0 Hz, 5 Hz, 10Hz and 20 Hz, respectively) on the forehead. The remaining 10 subjects formed the control group, in which they underwent a 30-minute rest period without light radiation. EEG signals of all subjects during each test were recorded. Gravity frequency (GF), relative energy change, and sample entropy were analyzed. The experimental groups had larger GF values compared to the control group. Higher stimulation frequency would cause larger growth of GF (F = 14.75, P < 0.001). The amplitude of alpha waves relative energy increased, while theta waves decreased remarkably in the experimental groups (p < 0.02), and the extent of increase/decrease was larger at higher stimulation frequency, compared to that of the control. Sample entropy of electrodes in the frontal areas were much larger than those in other brain areas in the experimental groups (p < 0.001). Larger frequency of the NIR LED light would cause more distinct brain activities in the stimulated areas. It indicates that NIR LEDlightmay have a positive effect onmodulating brain activity.These resultsmay help improve the design of photobiomodulation treatments in the future.

考虑到激光间质热疗时激光从内置在组织中的光纤输出且光束为有限宽光束,建立了内插光纤的双层球体组织模型;基于蒙特卡罗法获得无限窄光束在组织内的吸收值,利用入射光强与格林函数进行卷积计算,获得有限宽光束的光传输方程;以高斯光束和平圆光束为例,分别对比分析了考虑与不考虑内插光纤时组织对有限宽光束吸收情况的变化。结果表明:组织对平圆光束的吸收值较小、对高斯光束的吸收值较大,内插光纤对组织吸收平圆光束的影响较小,而对光子出射中心附近组织吸收高斯光束的影响较大。因此,采用高斯光束进行激光间质热疗时应考虑内插光纤对组织吸收光能的影响。所提模型更加接近激光间质热疗的实际情况,对准确预估激光间质热疗的热毁损范围具有重要的意义。

Accurate placement of pedicle screw (PS) is crucial in spinal surgery. Developing new real-time intra-operative monitoring and navigation methods is an important direction of clinical application research. In this paper, we studied the spectrum along the fixation trajectory of PS in frequency domain to tackle the accuracy problem. Fresh porcine vertebrae, bovine vertebrae and ovine vertebrae were measured with the near-infrared spectrum (NIR) device to obtain the reflected spectrum from the vertebrae. Along the fixation trajectory of PS, average energy from different groups was calculated and used for identifying different tissues and compared to achieve the optimal recognition factor. Compared with the time domain approach, the frequency domain method could divide the spectra measured at different tissue points into different groups more stably and accurately, which could serve as a new method to assist the PS insertion. The results gained from this study are significant to the development of hi-tech medical instruments with independent intellectual property rights.

Laser speckle contrast imaging (LSCI) is an optical imaging method, which can monitor microvascular flow variation directly without addition of any ectogenous dye. All the existing laser speckle contrast analysis (LASCA) methods are a combination of spatial and temporal statistics. In this study, we have proposed a new method, Gaussian kernel laser speckle contrast analysis (gLASCA), which processes the raw images primarily with the Gaussian kernel operator along the spatial direction of blood flow. We explored the properties of gLASCA in the simulation and animal cerebral ischemia perfusion model. Compared with the other existing speckle processing methods based on spatial, temporal, spatial-temporal or anisotropic linear structure; the present gLASCA method has a high spatial-temporal resolution to respond the change of velocity especially in microvasculature. Besides, the gLASCA method obtains approximately 10.2% and 7.1% higher contrast-to-noise ratio (CNR) over the anisotropic linear method (aLASCA) in the simulation and experiment models. For these advantages, gLASCA could be a better method for local microvascular laser speckle imaging in terms of cerebral ischemia reperfusion, spreading depression and brain injury diseases.

Because the brain edema has a crucial impact on morbidity and mortality, it is important to develop a noninvasive method to monitor the process of the brain edema effectively. When the brain edema occurs, the optical properties of the brain will change. The goal of this study is to access the feasibility and reliability of using noninvasive near-infrared spectroscopy (NIRS) monitoring method to measure the brain edema. Specifically, three models, including the water content changes in the cerebrospinal fluid (CSF), gray matter and white matter, were explored. Moreover, these models were numerically simulated by the Monte Carlo studies. Then, the phantom experiments were performed to investigate the light intensity which was measured at different detecting radius on the tissue surface. The results indicated that the light intensity correlated well with the conditions of the brain edema and the detecting radius. Briefly, at the detecting radius of 3.0 cm and 4.0 cm, the light intensity has a high response to the change of tissue parameters and optical properties. Thus, it is possible to monitor the brain edema noninvasively by NIRS method and the light intensity is a reliable and simple parameter to assess the brain edema.

During neurosurgery, an optical probe has been used to guide the micro-electrode, which is punc-tured into the globus pallidus (GP) to create a lesion that can relieve the cardinal symptoms. Accurate target localization is the key factor to affect the treatment. However, considering the scattering nature of the tissue, the “look ahead distance (LAD)" of optical probe makes the boundary between the different tissues blurred and difficult to be distinguished, which is defined as artifact. Thus, it is highly desirable to reduce the artifact caused by LAD. In this paper, a real-time algorithm based on precise threshold was proposed to eliminate the artifact. The value of the threshold was determined by the maximum error of the measurement system during the calibration procession automatically. Then, the measured data was processed sequentially only based on the threshold and the former data. Moreover, 100 m double-fiber probe and two-layer and multi-layer phantom models were utilized to validate the precision of the algorithm. The error of the algorithm is one puncture step, which was proved in the theory and experiment. It was concluded that the present method could reduce the artifact caused by LAD and make the real boundary sharper and less blurred in real-time. It might be potentially used for the neurosurgery navigation.

针对已有光纤安防系统入侵行为识别模型中特征空间不完备及分类器泛化能力差的缺陷，本文提出了一种光纤入侵行为融合特征的集成识别策略。首先，采用总体经验模态分解(Ensemble Empirical Mode Decomposition,EEMD)、功率谱分析(Power Spectral Analysis, PSA)及离散小波变换(Discrete Wavelet Transform, DWT)提取信号在时域、频域及小波域内振动信息，构建入侵信号的特征集。然后，提出一种基于DFPA(Discriminative FunctionPruning Analysis, DFPA)的特征选取方法，实现特征空间的约简。最后，构建集成的随机权向量函数连接网络(Random Vector Functional-Link net, RVFL)分类器识别入侵行为。在基于M-Z (Mach-Zehnder, M-Z)干扰仪的光纤安防系统中采集入侵信号，进行实验，结果表明该策略的有效性。

针对光纤周界安防系统入侵信号的非线性、非平稳性和间歇性等特点，提出了一种时域与频域特征相结合的方法，对光纤周界安防系统入侵振动信号进行识别与定位。采用计算嵌入维数方法，确定信号的最小分帧长度，因而能够较好地保留信号时间序列内在的动力学特性；提出了对入侵振动信号两级判定识别方法，利用短时能量和短时平均过零率特征来判断是否有振动信号产生，依据振动信号各层小波系数的能量分布特点来识别入侵信号，该方法有效地降低了周界安防系统的漏识率和误识率；为提高入侵信号定位的准确性，采用小波域贝叶斯自适应阈值对入侵信号作降噪处理，将重建的信号转换到频率域来确定入侵信号的位置。通过实验验证了所提方法的有效性。

研究光诱发和静息两种状态下的脑功能网络的信息传输枢纽、网络聚合能力和信息传输的最小路径的差异性。采用小世界网络理论对脑功能网络进行建模，通过对脑功能网络连接度、簇系数和最小路径进行分析，得出光诱发状态下的信息传输重要枢纽为岛叶、后扣带回功能区；丘脑、海马两处功能网络有较大聚合能力。光诱发过程从额上回经颞中回传输到枕中回。静息状态下的信息传输重要枢纽为楔叶、舌回；中央旁小叶、颞上回脑功能网络有较大聚合能力。静息状态下的左半区最佳信息传输路径为左额上回、左颞中回、右楔叶最后到左枕中回；右脑半区的为右额上回、右前扣带回、左枕下回最后到右枕中回。光诱发状态与静息状态的最佳传输路径有明显的区别。

采用近似熵算法得到19名健康志愿者在5 Hz频率的光（每秒光重复诱发5次）诱发前后的脑电(EEG)θ波段近似熵值(Apen θ)，经T-检验(P<0.05)发现光诱发后Apen θ值显著下降，其中在顶部、前额、颞部和枕部位置有显著性变化，颞部和枕部变化最大，左右半脑平均Apen θ均减少，右脑区更为显著。结果表明Apen θ能够描述外部光诱发情况下的EEG波段特征，并定量给出外部光诱发程度。