CSF -neurofilament correlates with outcome after aneurysmal subarachnoid hemorrhage

We investigated whether changing the frame rate at which speech video clips were presented (6-30 frames per second, fps) would affect audiovisual temporal perception. Participants made unspeeded temporal order judgments (TOJs) regarding which signal (auditory or visual) was presented first for video clips presented at a range of different stimulus onset asynchronies (SOAs) using the method of constant stimuli. Temporal discrimination accuracy was unaffected by changes in frame rate, while lower frame rate speech video clips required larger visual-speech leads for the point of subjective simultaneity (PSS) to be achieved than did higher frame rate video clips. The significant effect of frame rate on temporal perception demonstrated here has not been controlled for in previous studies of audiovisual synchrony perception using video stimuli and is potentially important given the rapid increase in the use of audiovisual videos in cognitive neuroscience research in recent years.     

Vessel Diameter Measurement from Intravital Microscopy

The blood vessel diameter is often measured in microcirculation studies to quantify the effects of various stimuli. Intravital video microscopy is used to measure the change in vessel diameter by first recording the video and analyzing it using electronic calipers or by using image shearing technique. Manual measurement using electronic calipers or image shearing is time-consuming and prone to measurement error, and automated measurement can serve as an alternative that is faster and more reliable. In this paper, a new feature-based tracking algorithm is presented for automatically measuring diameter of vessels in intravital video microscopy image sequences. Our method tracks the vessel diameter throughout the entire image sequence once the diameter is marked in the first image. The parameters were calibrated using the intravital videos with manual ground truth measurements. The expriment with 10 synthetic videos and 20 intravital microscopy videos, including 10 fluorescence confocal and 10 non-confocal transmission, shows that the measurement can be performed accurately.     

Gait performance is not influenced by working memory when walking at a self-selected pace

Gait performance exhibits patterns within the stride-to-stride variability that can be indexed using detrended fluctuation analysis (DFA). Previous work employing DFA has shown that gait patterns can be influenced by constraints, such as natural aging or disease, and they are informative regarding a person’s functional ability. Many activities of daily living require concurrent performance in the cognitive and gait domains; specifically working memory is commonly engaged while walking, which is considered dual-tasking. It is unknown if taxing working memory while walking influences gait performance as assessed by DFA. This study used a dual-tasking paradigm to determine if performance decrements are observed in gait or working memory when performed concurrently. Healthy young participants (N = 16) performed a working memory task (automated operation span task) and a gait task (walking at a self-selected speed on a treadmill) in single- and dual-task conditions. A second dual-task condition (reading while walking) was included to control for visual attention, but also introduced a task that taxed working memory over the long term. All trials involving gait lasted at least 10 min. Performance in the working memory task was indexed using five dependent variables (absolute score, partial score, speed error, accuracy error, and math error), while gait performance was indexed by quantifying the mean, standard deviation, and DFA α of the stride interval time series. Two multivariate analyses of variance (one for gait and one for working memory) were used to examine performance in the single- and dual-task conditions. No differences were observed in any of the gait or working memory dependent variables as a function of task condition. The results suggest the locomotor system is adaptive enough to complete a working memory task without compromising gait performance when walking at a self-selected pace.     

Gait metric profile of 157 patients suffering from anterior knee pain. A controlled study

PurposeGait metric alterations have been previously reported in patients suffering from anterior knee pain (AKP). Characterization of simple and measureable gait parameters in these patients may be valuable for assessing disease severity as well as for follow-up. Previous gait studies in this population have been comprised of relatively small cohorts and the findings of these studies are not uniform. The objective of the present study was to examine spatio-temporal gait parameters in patients with AKP in comparison to symptom-free controls. Furthermore, the study aimed to examine the relationship between self-reported disease severity and the magnitude of gait abnormalities.Methods157 patients with AKP were identified and compared to 31 healthy controls. Patients were evaluated with a spatiotemporal gait analysis via a computerized mat, the Western Ontario and McMaster Osteoarthritis Index (WOMAC) questionnaire and the Short Form (SF)-36 health surveys.ResultsAKP patients walked with significantly lower velocity (15.9%) and cadence (5.9%), shorter step length (9.5%), stride length (9.6%), and showed significant differences in all gait cycle phases (P < 0.05 for all). Study group reported higher levels of pain (96%), functional limitation (94%), and poorer perception of mental quality of life (30%) (P < 0.05 for all).ConclusionSignificant differences were found between the spatiotemporal gait profile of AKP patients and symptom-free matched controls. In addition, an association was found between subjective disease severity and gait abnormalities. These findings suggest the usefulness of gait parameters, alongside with the use of self-evaluation questionnaires, in identifying deviations of these patients from healthy population.     

Side by Side Treadmill Walking With Intentionally Desynchronized Gait

Humans demonstrate an innate desire to synchronize stepping when walking side by side. This behavior requires modification of each person’s gait, which may increase for pairings with very different walking patterns. The purpose of this study was to compare locomotor behavior for conditions in which partners exhibited similar and substantially different walking patterns. Twenty-six unimpaired subjects walked on a motorized treadmill at their preferred walking speed for three trials: by themselves (SOLO), next to someone on an adjacent treadmill (PAIRED), and next to someone who purposely avoided synchronization by altering stride times and/or lengths (DeSYNC). Means, coefficients of variance, approximate entropy (ApEn), rate of autocorrelation decay (α), and estimates of maximal Lyapunov exponents (λ*) were calculated for several dependent variables taken from sagittal plane kinematic data. Few differences in behavior were noted when the PAIRED condition was compared to the SOLO condition. However, the DeSYNC condition resulted in several alterations in ApEn, α, and λ*. These results suggest that greater differences in walking pattern between partners will facilitate greater modification to an individual’s gait. Additional study of side by side walking may hold implications for understanding the control of gait in humans and may have application in a clinical setting.     

Unsupervised quantification of whisking and head movement in freely moving rodents

The rodent whisker system has become the leading experimental paradigm for the study of active sensing. Thanks to more sophisticated behavioral paradigms, progressively better neurophysiological methods, and improved video hardware/software, there is now the prospect of defining the precise connection between the sensory apparatus and brain activity in awake, exploring animals. Achieving this ambitious goal requires quantitative, objective characterization of head and whisker kinematics. This study presents the methodology and potential uses of a new automated motion analysis routine. The program provides full quantification of head orientation and translation, as well as the angle, frequency, amplitude, and bilateral symmetry of whisking. The system operates without any need for manual tracing by the user. Quantitative comparison to whisker detection by expert humans indicates that the program's correct detection rate is at >95% even on animals with all whiskers intact. Particular attention has been paid to obtaining reliable performance under nonoptimal lighting or video conditions and at frame rates as low as 100. Variation of the zoom across time is compensated for without user intervention. The program adapts automatically to the size and shape of different species. The outcome of our testing indicates that the program can be a valuable tool in quantifying rodent sensorimotor behavior.     

基于深度神经网络和逐层相关性传播技术探究“高-低”里程跑者步态模式差异

目的 通过深度神经网络(deep neural network, DNN)分类模型揭示高里程跑者( high-mileage runner, HMR) 和低里程跑者 ( low-mileage runner, LMR) 跑 步 步 态 模 式 差 异, 并 探 讨 逐 层 相 关 性 传 播 ( layer-wise relevance propagation, LRP)技术解释 DNN 分类器模型的决策有效性。 方法 通过 DNN 对 HMR 和 LMR 总计 1 200 组跑步 步态特征数据进行训练分类识别,采用 LRP 计算相关变量在不同步态阶段的相关性得分( relevance score, RS),提 取高相关变量对步态模式差异进行解释性分析。 结果 DNN 对 HMR 和 LMR 的跑步步态模式特征分类精度达到 91. 25% 。 LRP 计算结果显示支撑前期(1% ~ 47% )各变量的成功分类贡献率高于支撑后期(48% ~ 100% )。 踝关节 相关轨迹变量 RS 的贡献率总和达到 43. 10% ,膝、髋关节贡献率分别为 37. 07% 、19. 83% 。 结论 膝、踝关节相关 生物力学参数对识别 HMR 和 LMR 步态特征的贡献程度最高。 跑步支撑早期可能包含更多步态模式信息,能够提 升步态模式识别的有效性和敏感性。 LRP 实现了对模型预测结果的可行性解释,从而为分析步态模式提供了更有 趣的见解和更有效的信息。     

痉挛型脑瘫患者功能性选择性脊神经后根切断术前后的三维步态特征分析

目的分析痉挛型脑瘫患者功能性选择性脊神经后根切断(functional selective posterior rhizotomy,FSPR)手术前后的步态特征,客观量化评估手术疗效。方法选取15名将要进行FSPR手术治疗的痉挛型脑瘫患者,应用VICON三维运动捕捉系统结合AMTI三维测力台对患者进行手术前后的步态采集,分析手术前后步态的时空、运动学及动力学参数。结果手术后,左、右支撑时间均大于手术前,左侧步长明显大于手术前,步高、步速及冠状面重心偏移均小于手术前;着地时的膝关节矢状面角度(即屈伸角度)出现明显提高,髋、踝关节未见明显差异。手术后,步行过程中左右侧髋、膝、踝关节活动范围(range of motion,ROM)在矢状面均出现不同程度的提高,且有统计学差异;右踝关节冠状面ROM也出现明显提高。手术后,右膝关节最小屈曲角度及左、右踝关节最大跖屈角度均出现显著减小;左、右侧支撑相最大垂直力较手术前明显提高,而下肢关节力矩未见明显差异。结论三维步态分析可以在一定程度上评估痉挛型脑瘫患者FSPR手术的疗效。术后痉挛型脑瘫患者的痉挛得到缓解,对步态的时空参数及下肢关节运动学参数改善比较明显,而对于动力学参数改善相对不明显,需进行进一步康复治疗。     

An automated method for analysis of microcirculation videos for accurate assessment of tissue perfusion

Imaging of the human microcirculation in real-time has the potential to detect injuries and illnesses that disturb the microcirculation at earlier stages and may improve the efficacy of resuscitation. Despite advanced imaging techniques to monitor the microcirculation, there are currently no tools for the near real-time analysis of the videos produced by these imaging systems. An automated system tool that can extract microvasculature information and monitor changes in tissue perfusion quantitatively might be invaluable as a diagnostic and therapeutic endpoint for resuscitation. The experimental algorithm automatically extracts microvascular network and quantitatively measures changes in the microcirculation. There are two main parts in the algorithm: video processing and vessel segmentation. Microcirculatory videos are first stabilized in a video processing step to remove motion artifacts. In the vessel segmentation process, the microvascular network is extracted using multiple level thresholding and pixel verification techniques. Threshold levels are selected using histogram information of a set of training video recordings. Pixel-by-pixel differences are calculated throughout the frames to identify active blood vessels and capillaries with flow. Sublingual microcirculatory videos are recorded from anesthetized swine at baseline and during hemorrhage using a hand-held Side-stream Dark Field (SDF) imaging device to track changes in the microvasculature during hemorrhage. Automatically segmented vessels in the recordings are analyzed visually and the functional capillary density (FCD) values calculated by the algorithm are compared for both health baseline and hemorrhagic conditions. These results were compared to independently made FCD measurements using a well-known semi-automated method. Results of the fully automated algorithm demonstrated a significant decrease of FCD values. Similar, but more variable FCD values were calculated using a commercially available software program requiring manual editing. An entirely automated system for analyzing microcirculation videos to reduce human interaction and computation time is developed. The algorithm successfully stabilizes video recordings, segments blood vessels, identifies vessels without flow and calculates FCD in a fully automated process. The automated process provides an equal or better separation between healthy and hemorrhagic FCD values compared to currently available semi-automatic techniques. The proposed method shows promise for the quantitative measurement of changes occurring in microcirculation during injury.     

Gait function in adults with Williams syndrome

Despite early neurological reports of gait abnormalities in Williams syndrome (WS), a rare genetically based neurodevelopmental disorder, there has not yet been any systematic investigation of gait dysfunction in this disorder. The current study examined the gait characteristics in adults with WS and a neurologically normal control group as they walked at self-selected slow, preferred and fast speeds using the GAITRite walkway. The WS group showed hypokinetic gait, which manifested as reduced gait speed and stride length, but with a disproportionate increase in cadence (stepping frequency) as speed was increased. The WS group also showed increased variability of stride length and a broad based stepping pattern implicating a compensatory strategy for postural instability. Performance IQ correlated significantly with stride length in the WS group. While these results should be considered preliminary due to the small sample size, these findings have implications for our understanding of the neural basis of gait dysfunction in WS.     

Gait analysis in the mouse.

The gait of the adult Swiss (Mike Flack--MF1 subtype) mouse during spontaneous walk/trot locomotion at velocities ranging from 14-43 cm s(-1) has been analysed using simultaneous video and reaction force analysis. No differences were observed between males and females. Velocity adjustments within this range are accounted for to a greater extent (>70%) by stride time decreases and to a lesser degree (<30%) by stride length increases. Equivalent stride times for fore and hindlimbs were, in the former, composed of a shorter stance and a longer swing time. Peak vertical reaction force increases with decreasing stance time, with that for the forelimb being about 5% greater than that for the hindlimb across the whole stance time range studied. The areas under the vertical reaction force curves for fore and hindlimbs are, however, not significantly different. The results are discussed in the light of in vitro work cycle studies on the properties of some of the major hindlimb locomotor mouse muscles, and with previously established data in the rat. It is concluded that the mouse shows a consistent and quantifiable gait that would allow incorporation of locomotor assessment into the evaluation of a number of pathophysiological states.     

Gait abnormalities in older people--comparison of inter-professional assessment

Gait abnormalities are common in older people but relatively under-diagnosed. We investigated the prevalence of gait abnormalities among patients presenting to a geriatric medicine day hospital, classified them according to whether they were lower, middle or higher level gait disorders and compared inter-professional (physician and physiotherapist) assessments for this classification. Prospective independent assessment by a physician and a senior physiotherapist of 50 consecutive patients presenting to a day hospital. Presence of a gait abnormality was determined and then classified. Levels of agreement were determined between the two professions. There was 98% agreement that a gait abnormality existed in 43 people. In classifying the gait abnormality there was complete agreement in over two-thirds of cases (67.4%). There was further agreement of higher level gait disorders (but disagreement in the sub-classification) in 11.6% of cases. Given the high prevalence of gait abnormality presenting to the day hospital, screening for gait and balance disorders should be of paramount importance. While levels of agreement between the two professions were high, disagreement existed in approximately one-third of cases. Agreement among professionals essential for appropriate tailoring of treatment and intervention.     

Video-based Gait Analysis for Functional Evaluation of Healing Achilles Tendon in Rats

Video-based walking track systems have been developed for gait analysis in rat models. However, there is no previous study using video-based tracking systems to address the gait parameters to evaluate the recovery of Achilles tendon rupture models. This study conducted a comprehensive gait analysis using a video-based image processing system. Eighteen Sprague-Dawley rats were randomly assigned to one of three interventional conditions: sham surgery, Achilles tendon repair, and Achilles tendon defect. After surgery, all animals were evaluated using a video-based walking track system. The gait parameters and the Achilles functional index (AFI) were further analyzed. The ankle joint angles of the injury side at mid-stance and pre-swing were highly correlated with the AFI. However, lack of sensitivity was found for the AFI. Increased measurement sensitivity of the Achilles tendon healing condition was found in the ankle joint angle of the involved side at the pre-swing and the level of asymmetry of the hindlimb joint position and stance/swing time. The overall sensitivity of the ankle motion analysis was significantly higher than that of AFI. We conclude that the ankle motion analysis is a reliable, reproducible, and sensitive tool for Achilles tendon analysis in rats.     

基于软件OpenSim的人体运动建模理论及其应用领域概述

红外捕捉系统、高速摄像、平面摄影、表面肌电测试等现行实验室测试手段不能显示人体运动时肌肉产生肌力的具体信息以及准确阐释神经-肌肉协调机制。因此,计算机模拟与仿真应运而生。目前,国内用来进行人体动作仿真的软件主要有Life MOD、Any Body、ANSYS等,这些软件有其自身的缺陷,如肌肉控制不够精确、价钱昂贵等。为了更好解决肌肉模拟问题,斯坦福大学团队研发了一款免费软件Open Sim,它是基于C++和JAVA语言开发的一款应用于肌肉模型开发、模拟仿真与分析神经肌肉系统的开放性软件。以计算机建模与数学理论推导为基础,对Open Sim建模理论和步骤进行详细介绍,为国内从事运动生物力学研究学者提供一些理论参考;同时,探讨未来利用Open Sim建模仿真研究的主要方向,例如通过Open Sim的模拟研究可以探求偏瘫步态、帕金森步态等异常步态的神经-肌肉机制,为异常步态康复手段的改进和完善提供依据。     

基于足底动力学测试的步态分析

目的：分析连续步态的特征参数,研究一个完整步态周期所对应的垂直反作用力变化以及能量消耗变化,为扩展和完善步态分析系统提供依据。方法：采用德国zebrisFDM步态测试系统测得173名正常人自然行走过程中足底压力数据,根据连续信号和时相对称性指标进行两次数据筛选,最终选取了23名（相对称性指数〉0．95）较适宜的步态数据,分别导人SPSS软件进行统计分析及matlab软件进行编程画图。结果：通过分析步速的影响因素得出步速与跨步长,身高的相关性最高（r=．884）,而与步态周期、站立相时间高度负相关;编程实现了一个完整步态周期中均值与标准差同时显示的左右脚压力曲线,峰值定量化得出第一峰值约为体重的1．05—1．08倍,出现在步态周期的14％左右,第二峰值约为体重的1．13～1．16倍,出现在步态周期的47％左右;独立样本检验得出能量消耗指数与时相对称性指数用于正常人步态检验无显著差异（P〉0．05）。结论：人在自然行走时其步速与跨步长／身高高度相关,其垂直反作用力与体重高度相关：并且能量消耗指数在评定正常人步态功能方面是可行的。     

步态水平对髋关节假体周围骨重建的影响

目的 针对髋关节置换术后患者步态运动水平变化,研究假体周围骨密度（bone mineral density, BMD）变化率的变化趋势,揭示置换初期、长期运动变化对骨重建的影响规律。方法 基于自适应骨重建理论,建立股骨-假体有限元模型,以术后初期、长期步态水平作为重建参数计算假体周围BMD分布,采用Gruen分区方法量化BMD的变化。结果 术后初期,恒定步态组与变化步态组BMD存在明显差异,最大差异发生在低步态组中,造成大转子区域BMD减小41%;步态运动提高促进假体近端、中端BMD变化,显著影响发生在大转子区域,造成BMD增加47%;术后长期阶段,步态运动提高促进假体中端、末端区域BMD恢复,BMD增加2%～9%。结论 研究结果为髋关节置换后患者康复过程提供指导。     

单侧全髋关节置换后遗症期的下肢步态参数

背景：全髋关节置换可以为患者缓解疼痛、恢复步行功能,数年后步态是否能达到正常化仍存在争议。 目的：分析单侧髋关节置换后遗症期患者平地步行中下肢的时空参数特征,探讨患者步行能力。 方法：根据运动重建实验室检测病例数据库资料分析的方法,选择全髋关节置换后5-10年的患者14例为实验组,14例相匹配的健康人为对照组。采用Vicon Nexus采集患者平地步行时下肢的步态参数,应用Polygon分析步态周期中下肢时空参数特征。 结果与结论：与对照组相比,实验组术侧和健侧步速减慢,步频减小,步幅、跨步长变短,双支撑相延长,对侧足离地比增大(P < 0.05);术侧跨步时间、单步时间增大(P < 0.05);健侧足离地比增大(P < 0.05)。术侧与健侧比较,各时空参数差异均无显著性意义(P > 0.05)。结果表明全髋关节置换后5-10年的患者步态对称性较好,但仍没有达到正常水平,步行能力差于正常人,需要系统康复训练以恢复其步行能力。中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程全文链接：     

步态生物力学大数据分析研究进展

目的 研究目前步态生物力学大数据分析的前沿进展。方法 以2011～2020年步态生物力学大数据分析相关的科技文献为研究对象,运用内容分析法,从主题结构、层级水平、模型类型和分析技术4个方面进行分析与讨论,并在此基础上对步态生物力学大数据分析的未来研究进行展望。结果 大数据分析在步态生物力学的应用领域主要有5个层面,分别为干预和康复、运动训练、假肢设计和评估、了解病因和诊断、了解人移动的特点;步态生物力学领域大数据分析分为3个层级水平,其中描述性分析是使用最多的类型,约占41%;系统回顾步态生物力学领域大数据分析的模型和具体技术;拓扑数据分析是一个非常有前途的大数据探索工具。结论 大数据技术在步态生物力学和临床医学研究中具有巨大潜力。     

Gait Variability is Altered in Older Adults When Listening to Auditory Stimuli with Differing Temporal Structures

Gait variability in the context of a deterministic dynamical system may be quantified using nonlinear time series analyses that characterize the complexity of the system. Pathological gait exhibits altered gait variability. It can be either too periodic and predictable, or too random and disordered, as is the case with aging. While gait therapies often focus on restoration of linear measures such as gait speed or stride length, we propose that the goal of gait therapy should be to restore optimal gait variability, which exhibits chaotic fluctuations and is the balance between predictability and complexity. In this context, our purpose was to investigate how listening to different auditory stimuli affects gait variability. Twenty-seven young and 27 elderly subjects walked on a treadmill for 5 min while listening to white noise, a chaotic rhythm, a metronome, and with no auditory stimulus. Stride length, step width, and stride intervals were calculated for all conditions. Detrended Fluctuation Analysis was then performed on these time series. A quadratic trend analysis determined that an idealized inverted-U shape described the relationship between gait variability and the structure of the auditory stimuli for the elderly group, but not for the young group. This proof-of-concept study shows that the gait of older adults may be manipulated using auditory stimuli. Future work will investigate which structures of auditory stimuli lead to improvements in functional status in older adults.