山羊颈椎能成为人类颈椎的良好模型吗?

目的比较山羊与人颈椎的体外三维生物力学特征.方法取新鲜成年人尸体与崇明山羊颈椎标本(C0～T1)各8具,在脊柱三维运动测试仪上检测两者屈曲、后伸、左右侧屈、左右轴向旋转等模式下的运动范围和中性区.结果在前屈运动方式下,山羊和人C1-2的ROM分别为16.9°±5.1°和14.3°±3.2°,超过其它节段.在后伸运动方式下,山羊与人C1-2的ROM分别为20.6°±4.8°和18.7°±3.7° C0-1的ROM分别为19.3°±4.7°和18.4°±4.3°,超过其它节段.在轴向旋转运动模式下,山羊与人C1-2的ROM分别为48.60±8.6°和56.3°±8.9°.除山羊C4-7左右侧屈的NZ与人相比有统计学差异(P＜0.05)外,其它节段前屈、后伸、轴向旋转及左右侧屈的ROM和NZ与人相比无统计学差异(P＞0.05).结论崇明山羊与人颈椎在前屈、后伸、左右侧屈和轴向旋转等运动模式下的ROM及NZ相近,可作为颈椎研究的良好动物模型.     

定点旋转手法作用下颈椎各节段亚生理区的运动形式

目的测量颈椎定点旋转手法作用下颈椎运动节段在亚生理区内的运动形式及各节段的亚生理区。方法取2具急性脑死亡的男性青年新鲜尸体的颈椎做标本,固定于MTS实验机上,模拟颈椎定点旋转手法,同时实时采集各运动节段三维坐标,计算出各节段在亚生理区内的运动形式。结果在C4定点对抗牵引作用下,C1～2生理活动范围最大,左、右两侧分别为22.65°、17.68°,其余3个节段依次减小。C4～5亚生理区最小,左、右两侧分别为0.55°和0.84°,其他节段离C4定点区越远,亚生理区范围越大。颈椎在亚生理区内转动时,各运动节段都有后伸和向旋转对侧侧弯的耦合运动;在亚生理区内,除C1～2节段向下移动外,其余椎体均向上移动;而水平侧方和前后移位上,C2～3节段运动形式与其他节段相反。结论颈椎各节段的亚生理区大小不同,离定点区越远的节段亚生理区越大,并且在亚生理区内各节段运动形式具有较大的差异。     

颈椎人工椎间盘置换有限元分析

目的　建立C4~5节段PrestigeTM-LP颈椎人工椎间盘植入后的三维有限元模型,进行手术节段的运动分析。 方法 采用对成年男性的新鲜尸体的颈椎标本进行CT三维扫描方法建立C4~5节段和PrestigeTM-LP人工间盘有限元,模拟完成C4~5人工椎间盘置换手术。测量生理加载下手术节段前屈/后伸、侧弯及轴向旋转运动角度。结果 有限元模型对颈椎的结构,包括椎体间韧带、颈椎关节突关节、钩椎关节等均进行了精确的重建,并较好地模拟手术操作进行PrestigeTM-LP人工间盘植入。运动加载后运动角度,前屈5.7°,后伸3.5°,侧弯5.0°,旋转11.3°,与文献报道结果较为接近。 结论　有限元模型具有精确度高,手术模拟真实的特点,可作为颈椎人工椎间盘生物力学研究的一种较好途径。PrestigeTM-LP颈椎人工椎间盘置换可较好地保留手术节段的运动功能。     

上颈椎C0-C3节段不同载荷作用下生物力学特性的有限元分析

研究上颈椎C0-C3活动节段在不同载荷作用下前屈、后伸、侧屈和旋转时椎体应力、关节活动度(range of motion,ROM)及椎间盘的应力分布情况,探讨载荷改变对上颈椎生物力学特性的影响。基于CT图像数据建立人体上颈椎有限元模型,模型包括皮质骨、松质骨、纤维环、髓核、关节软骨、终板及韧带等结构,根据解剖特征赋予不同部位的材料属性,计算分析上颈椎C0-C3各节段在不同力矩作用下屈伸旋转时颈椎ROM、椎体应力和椎间盘最大应力变化趋势,与前人离体试验和有限元结果进行对比验证。人体上颈椎C0-C3节段在40 N和1.5 N·m载荷作用下,前屈时ROM最小,C0-C1、 C1-C2、C2-C3各节段ROM分别为1.88°、2.16°和1.59°;后伸时ROM大于前屈,最大相差幅度为2.32°;侧屈时ROM大于前屈,增幅分别为2.57°、2.41°和0.49°;轴向旋转时ROM最大,相对于侧屈ROM分别增加了247.64%、282.71%和-43.27%。当施加40 N预载荷和1.0、1.5、2.0、2.5 N·m力矩时,随着力矩等值增大,上颈椎C0-C3节段整体ROM呈非线性增加,变化特征为前屈时最小,旋转时最大;椎间盘最大应力值呈非线性增加(前屈和侧屈)和减少(后伸和旋转),ROM和应力分布趋势和前人研究结果一致。上颈椎三维有限元模型在不同载荷下数值分析的结果符合正常人体颈椎生理活动范围和生物力学特性,为临床颈椎病理和生理的生物力学研究提供理论依据。     

腰椎单节段棘突问CoflexTM固定对脊柱三维运动的影响

目的:探讨棘突间稳定装置CoflexTM单节段固定后对固定及邻近节段活动度的影响.方法:选取6具新鲜成人尸体脊柱标本(L1～S1段),进行前屈/后伸、左右侧弯/旋转6个运动方向的稳定性测试.计算L2/3,L3/4和L4/5的=三维运动范围(ROM)和中性区(NZ),分别比较完整标本(a);CoflexTM固定L3/4(b);L3/4双侧部分失稳(c);c+b(d)4种状态下3个节段的活动度.结果:ROM值:L3/4前屈时状态b＜a,d＜c(P＜0.01),后伸时状态b、d＜a、c(P＜0.01),旋转时状态b＜a、d＜c(P＜0.05);L2/3和L4/5后伸时状态b、d＞a、C(P＜0.05),前屈及旋转时无差别(P＞0.05);侧弯时3个节段4种状态下均无差别(P＞0.05).结论:CoflexTM可以限制同定节段的前屈、后伸和旋转运动,使上下各一个邻近节段后伸活动度增加,前屈和旋转活动度无变化;对侧弯活动度均无影响.     

寰枢关节后路动态固定的生物力学研究

目的探讨动态固定(转动钉、滑动钉)对寰枢关节稳定性的影响。方法用6具新鲜成人枕骨(Oc)～颈椎(C4)节段进行测试,分别模拟完整状态、损伤状态、坚强固定、转动钉固定、滑动钉固定。采用重复测量的实验设计,在完整、损伤和不同固定状态下,通过脊柱试验机对标本分别施加1.5 N·m前屈/后伸、左/右侧弯和左/右轴向旋转纯力偶矩。三维运动系统测量寰枢椎运动,分析比较固定节段角度的运动范围(range of motion,ROM)和中性区(neutral zone,NZ)。结果损伤状态下,寰枢关节ROM在前屈、后伸、侧弯和旋转方向上均显著增加,产生了寰枢关节不稳。在前屈、后伸、侧弯和旋转方向上,坚强固定和动态固定后ROM均显著减小。与坚强固定比较,动态固定仅在侧弯方向上ROM较大。动态固定显著减小了在屈伸、侧弯和旋转方向上的NZ,且与坚强固定之间的差异无显著性。结论寰枢关节动态固定后,在前屈、后伸和旋转方向上的稳定性与坚强固定相当,但在侧弯方向上较弱。动态固定能够维持寰枢关节的相对稳定。     

单开门椎管扩大术对颈椎运动影响的生物力学研究

本文定量地研究了正常颈椎和单开门椎管扩大术（Ｅ０ＤＬ）后的颈椎（Ｃ２～６）各节段的运动。采用７例新鲜的青年颈椎标本（枕骨至Ｃ７），施加力偶最大为１．５Ｎｍ，使之产生前屈、后伸和左、右侧弯运动。从正、侧位的照片上分别测量颈椎的前屈、后伸和左、右侧弯运动。每种力偶都加载、卸载三次。计算中性区、弹性区和运动范围．在Ｃ２～５或Ｃ３～５行单开门椎管扩大术后，与正常颈椎运动相比较，Ｃ２～各节段的前屈、后伸和左、右侧弯均无显著性差别。可见单开门椎管扩大术不会造成颈椎的不稳。     

脊柱三维运动分析和颈椎稳定性的实验研究

本文研制了基于双平面立体测量和计算机图像处理的脊柱三维运动的分析系统，该系统可以确定椎体的空间位置和节段间的线位移和角位移。颈椎双侧小关节切除可导致颈椎不稳定，需植骨融合或内固定。本文对Ｈａｌｉｆａｘ椎板夹和棘突钢丝固定进行了生物力学评价，作为恢复稳定性的一个指标，为临床上选择合适的固定形式提供依据。在９具新鲜成人颈椎标本（Ｃ３－Ｔ１）上、对双侧７５％小关节切除后失稳的Ｃ４－５节段，安放了Ｈａｌｉｆａｘ椎板夹和棘突钢丝固定，通过脊柱三维运动稳定性评价方法，评价它们重建颈椎稳定性的即刻效果。本文研究表明：（１）Ｈａｌｉｆａｘ椎板夹能够在前屈、后伸和侧弯运动方向上加强节段的稳定性，恢复节段的轴向旋转运动的稳定性；（２）棘突钢丝固定在前屈运动方向上可加强节段的稳定性，可恢复节段在后伸、侧弯和轴向旋转运动方向上的稳定性；（３）棘突钢丝固定后节段的前屈、后伸和侧弯运动范围均大于Ｈａｌｉｆａｘ椎板夹固定后的运动范围，尤其是在限制前屈运动时，Ｈａｌｉｆａｘ椎板夹的固定作用更为明显，但两者限制颈椎轴向旋转运动的能力相近。     

正常颈椎有限元模型建立及有效性验证

目的：建立颈椎C2～C7节段三维有限元模型,分析模型的生物力学特征,进行有效性验证。方法：招募一名健康志愿者为建模对象,利用64排螺旋CT进行颈椎连续性断层扫描,扫描区域设定为枕骨至C7椎体节段。将获得的图像数据DICOM文件导入至Mimics图像分割软件中,对颈椎骨性结构进行分割提取。在Geomagic studio软件中对获得的颈椎骨性结构模型进行去噪、光顺、修补填充等处理,拟合曲面实体,并偏移分割生成皮质骨与松质骨,将模型保存为STEP文件。在Solidworks软件中完成椎间盘髓核、纤维环及关节软骨结构的建立与模型的组装匹配。ANSYS Workbench软件中添加材料属性、接触关系、边界条件及载荷,测量颈椎在前屈、后伸、左右侧弯、左右旋转6种应力作用下位移变化。结果：成功建立颈椎C2～C7节段有限元模型,颈椎C2～C3屈伸、侧屈、旋转角度位移分别为7.2°、8.2°、5.3°,颈椎C3～C4屈伸、侧屈、旋转角度位移分别为7.2°、8.1°、6.2°,颈椎C4～C5屈伸、侧屈、旋转角度位移分别为8.1°、7.9°、7.8°,颈椎C5～C6屈伸、侧屈、旋转角度位移分别为6.9°、...     

颈椎双节段融合术后各节段运动补偿的规律研究

目的　探讨颈椎双节段融合术后上、下相邻及非相邻节段的运动补偿规律。 方法　通过三维运动采集系统捕捉到6具新鲜人尸体颈椎双节段融合术前、后C2~T1各节段在前屈、后伸、左侧屈、右侧屈、左旋转、右旋转6种状态下的运动角度数据,并将结果进行分析。 结果　经过归一化处理后,分析得出颈椎双节段融合术后各节段的运动变化规律,发现融合术后其他各节段六种运动状态下运动幅度均有不同程度的增加,尤其是下相邻节段,差异均有统计学意义（P<0.05）。其中后伸、前屈及双向侧屈融合效果更好,稍优于左旋及右旋状态下的融合效果。而在运动补偿比例这点,各运动状态,下相邻节段的运动补偿比例（平均值大于30%）也远高于其它节段。 结论　颈椎双节段融合术后邻近节段的代偿性运动幅度增加是导致其退变的重要原因。     

Adaptive bulk motion exclusion for improved robustness of abdominal magnetic resonance imaging

Non‐Cartesian magnetic resonance imaging (MRI) sequences have shown great promise for abdominal examination during free breathing, but break down in the presence of bulk patient motion (i.e. voluntary or involuntary patient movement resulting in translation, rotation or elastic deformations of the body). This work describes a data‐consistency‐driven image stabilization technique that detects and excludes bulk movements during data acquisition. Bulk motion is identified from changes in the signal intensity distribution across different elements of a multi‐channel receive coil array. A short free induction decay signal is acquired after excitation and used as a measure to determine alterations in the load distribution. The technique has been implemented on a clinical MR scanner and evaluated in the abdomen. Six volunteers were scanned and two radiologists scored the reconstructions. To show the applicability to other body areas, additional neck and knee images were acquired. Data corrupted by bulk motion were successfully detected and excluded from image reconstruction. An overall increase in image sharpness and reduction of streaking and shine‐through artifacts were seen in the volunteer study, as well as in the neck and knee scans. The proposed technique enables automatic real‐time detection and exclusion of bulk motion during MR examinations without user interaction. It may help to improve the reliability of pediatric MRI examinations without the use of sedation.     

Initiation of smooth-pursuit eye movements to first-order and second-order motion stimuli

Since normal human subjects can perform smooth-pursuit eye movements only in the presence of a moving target, the occurrence of these eye movements represents an ideal behavioural probe to monitor the successful processing of visual motion. It has been shown previously that subjects can execute smooth-pursuit eye movements to targets defined by luminance and colour, the first-order stimulus attributes, as well as to targets defined by derived, second-order stimulus attributes such as contrast, flicker or motion. In contrast to these earlier experiments focusing on steady-state pursuit, the present study addressed the course of pre-saccadic pursuit initiation (less than 100 ms), as this early time period is thought to represent open-loop pursuit, i.e. the eye movements are exclusively driven by visual inputs proceeding the onset of the eye movement itself. Eye movements of five human subjects tracking first- and second-order motion stimuli had been measured. The analysis of the obtained eye traces revealed that smooth-pursuit eye movements could be initiated to first-order as well as second-order motion stimuli, even before the execution of the first initial saccade. In contrast to steady-state pursuit, the initiation of pursuit was not exclusively determined by the movement of the target, but rather due to an interaction between dominant first-order and less-weighted second-order motion components. Based on our results, two conclusions may be drawn: first and specific for initiation of smooth-pursuit eye movements, we present evidence supporting the notion that initiation of pursuit reflects integration of all available visual motion information. Second and more general, our results further support the hypothesis that the visual system consists of more than one mechanism for the extraction of first-order and second-order motion.     

脊柱生物力学信号智能分析系统的研究

目的为脊柱生物力学测试平台开发一套信号智能分析系统,对不同采集装置产生的海量数据进行格式规范与整合,实现对数据的科学管理和快速处理。方法利用OptotrakCertus运动测量系统、MTS材料试验机和USB数据采集卡,以Matlab和MySQL为软件开发平台,搭建脊柱生物力学信号智能分析系统。对脊柱模型的生物力学性能进行测试,测试参数主要包括脊柱各节段运动角度、加载力矩。结果由系统自动处理得到的脊柱各节段运动角度变化规律,与力及力矩载荷的变化一致。结论本系统能有效应用于脊柱及其内固定器械的生物力学测试中。     

基于冠状动脉造影图像序列的心脏三维运动模型

本研究提出了一种根据单面冠状动脉造影图像序列分析心脏三维运动的算法。根据心脏运动的先验知识，建立了包含心脏主要运动形式的运动模型，按照从整体到局部的顺序，将心脏的复杂运动分解为整体刚性运动、整体变形以及局部运动和变形，并估计其参数。利用估计出来的各运动组成部分的参数，得到对心脏运动的量化描述。     

Single‐voxel MRS with prospective motion correction and retrospective frequency correction

Subject motion during MRS investigations is a factor limiting the quality and the diagnostic value of the spectra. The possibility of using external motion tracking data to correct for artefacts in MR imaging has been demonstrated previously. In this paper the utility of prospective motion correction for single‐voxel proton MRS is investigated. The object motion data are used in real time to update the position of the spectroscopy voxel during the acquisition prior to every sequence repetition cycle. It is not, however, sufficient to update the voxel position alone due to shim changes accompanying subject motion. Adverse effects of frequency shifts induced by subject motion are effectively suppressed by the interleaved reference scan method. Copyright © 2010 John Wiley & Sons, Ltd.     

Effects of stimulus field size and coherence of visual motion on cortical responses in humans: an MEG study

Among various kinds of visual motion, wide field coherent visual motion should have characteristic physiological significance regarding the relationship between the external world and us. To detect veridical visual motion in the surrounding environment, specific mechanisms are necessary to differentiate it from the wide field coherent motion due to one's own movement. To disclose whether and how the neural process of wide field coherent motion is different from that of other motions, we measured cortical responses to visual motions in humans using magnetoencephalography (MEG) manipulating both field size and coherence. Results showed that an increase in field size enhanced the response at sensors around the parieto-occipital area, and that the difference in activity between coherent and incoherent motion tended to be larger for the wide field. These findings suggest that wide field coherent and incoherent motion is detected differently at least in part in the parieto-occipital area, and suggest the neural process of wide field coherent motion could be pronouncedly tapped by a combination of field size and coherence.     

Travel distance estimation from visual motion by leaky path integration

Visual motion can be a cue to travel distance when the motion signals are integrated. Distance estimates from visually simulated self-motion are imprecise, however. Previous work in our labs has given conflicting results on the imprecision: experiments by Frenz and Lappe had suggested a general underestimation of travel distance, while results from Redlick, Jenkin and Harris had shown an overestimation of travel distance. Here we describe a collaborative study that resolves the conflict by tracing it to differences in the tasks given to the subjects. With an identical set of subjects and identical visual motion simulation we show that underestimation of travel distance occurs when the task involves a judgment of distance from the starting position, and that overestimation of travel distance occurs when the task requires a judgment of the remaining distance to a particular target position. We present a leaky integrator model that explains both effects with a single mechanism. In this leaky integrator model we introduce the idea that, depending on the task, either the distance from start, or the distance to target is used as a state variable. The state variable is updated during the movement by integration over the space covered by the movement, rather than over time. In this model, travel distance mis-estimation occurs because the integration leaks and because the transformation of visual motion to travel distance involves a gain factor. Mis-estimates in both tasks can be explained with the same leak rate and gain in both conditions. Our results thus suggest that observers do not simply integrate traveled distance and then relate it to the task. Instead, the internally represented variable is either distance from the origin or distance to the goal, whichever is relevant.     

基于模型的人体运动参数检测

人体运动参数检测是生成人体运动计算机仿真演示和控制拟人机器人运动的主要手段。近年来针对这种检测方法国内外研究人员展开了广泛的研究。本文介绍了基于模型的人体运动参数检测方法的研究现状 ,为人体仿生学和拟人机器人等领域的科学研究提供依据     

Left-to-right shunt in atrial septal defect: Quantification by echocardiography

Summary Time motion echocardiograms (ECHO) of 30 patients with atrial septal defect (ASD) and 36 individuals without heart disease (C) were comparatively studied to see whether parameters may be defined indicating the size of the left-to-right shunt (LRS). The diagnosis was proven by cardiac catheterization; in the patients with ASD the pulmonic-to-systemic blood flow ratios,Q _p:Q _s, ranged from 1.33 to 3.85:1, and pulmonary vascular resistance was normal. The ratio of the left (LVD) and right ventricular dimension (RVD), LVD:RVD, and the RVD indices of the patients with ASD were significantly different from those of the C:1.07±0.04 vs. 3.1±0.03 and 22.5±0.5 vs. 9.8±0.2 mm/m² respectively (mean ±1 SEM),p0.001. These parameters and the abnormal interventricular septal motion in 84% of patients with ASD did not correlate with the size of the LRS. However, the ratioQ _p:Q _s between 1.33 and 3.85:1 linearly correlated with the ratio derived from the maximal diastolic opening of the tricuspid (TVO) and mitral valve (MVO), TVO:MVO, with a coefficient ofr=0.76,p < 0.001. In each patient with ASD and aQ _p:Q _s ratio 1.4:1 the ratio TVO:MVO was > 1.15, while in the C TVO:MVO ranged from 0.7–1.13 with a mean of 1.02±0.01 (1 SEM). The data suggest that in patients with ASD a significant left-to-right shunt may be quantified by ECHO and that these patients may be separated either from patients with ASD and a small LRS and/or from normal subjects.Supported by the Deutsche Forschungsgemeinschaft (Bo 435/2 and SFB 90-Kardiovaskuläres System — der Universität Heidelberg)     

Information processing during physical exercise: a chronometric and electromyographic study

We compared quantitatively the psychometric capacity of human subjects to detect path-guided apparent motion (PAM) and the accuracy of cell ensembles in area 7a to code the same type of stimuli. Nine human subjects performed a detection task of PAM. They were instructed to indicate with a key-press whether they perceived a circularly moving object when five stimuli were flashed successively at the vertices of a regular pentagon. The stimuli were presented along a low contrast circular path with one of 33 speeds (150–600°/s). The average psychometric curve revealed that the threshold for PAM detection was 314°/s. The minimum and maximum thresholds for individual subjects were 277° and 378°/s, respectively. In addition, the activity of cells in area 7a that were modulated by the stimulus position in real or apparent motion was used in a multivariate linear regression analysis to recover the stimulus position over time. Real stimulus motion was decoded successfully from neural ensemble activity at all speeds. In contrast, the decoding of PAM was poor at low stimulus speeds but improved markedly above 300°/s: in fact, this was very close to the threshold above for human subjects to perceive continuous stimulus motion in this condition. These results suggest that the posterior parietal cortex is part of a high-level system that is directly involved in the dynamic representation of complex motion