IGRT and motion management during lung SBRT delivery

Patient motion can cause misalignment of the tumour and toxicities to the healthy lung tissue during lung stereotactic body radiation therapy (SBRT). Any deviations from the reference setup can miss the target and have acute toxic effects on the patient with consequences onto its quality of life and survival outcomes. Correction for motion, either immediately prior to treatment or intra-treatment, can be realized with image-guided radiation therapy (IGRT) and motion management devices. The use of these techniques has demonstrated the feasibility of integrating complex technology with clinical linear accelerator to provide a higher standard of care for the patients and increase their quality of life.     

Polarization vision in crayfish motion detectors

Motion detector interneurons were examined to determine their responsiveness to the motion of polarized light images (i.e. images segmented by spatial variations in e-vector angle). Computer generated images were displayed as intensity contrasts or polarization contrasts on a modified LCD projection panel. The stimuli included the motion of a single stripe (45 degrees -55 degrees /s) and the global motion of a square wave grating (3.3 degrees /s). Neurons were impaled in the medulla interna. Of the neurons which exhibited a directional response to the motion of intensity contrast stimuli, about 2/3 were also directional in the response to polarized light images. Transient (nondirectional) stimuli included looming and jittery motions. The responses to the transient motions of the polarized light images were roughly comparable to those elicited by intensity contrast. The results imply that behavioral responses to polarized light images (i.e. optokinetic and defense reflexes) may have a basis in the polarization sensitivity and synaptic organization of the medulla interna.     

猫前内侧上雪氏区视神经元对运动随机线条的反应

对于运动信息在脑内的加工,一种观点认为分两阶段进行,低级视皮层只对运动图形内部成分的取向进行调谐,高级视皮层整合低级视皮层的输入,对图形整体的运动方向敏感。用网格（plaid）作为刺激的实验表明,在较低级皮层区,细胞多表现为成分方向选择性（Component-motion Selectivity),即对刺激中的取向因素敏感：而较高视皮层的细胞多表现为整体方向选择性（Pattern-motion Selecitivity),对运动整体的方向敏感,从而支持运动信息加工的“两阶段”理论。实验中,用一系列运动随机线条刺激（random line patterns)。研究猫前内侧上雪氏区（Anteriormedial lateral suprasylvian area,AMLS)神经元的方向调谐特性。结果表明多数细胞为整体方向选择性,且随线长增加此类细胞比例下降,而成分方向选择性细胞的比例有所增加,呈现由整体方向选择性向中间类型（Unclassified),由中间类型向成分方向选择性变化的趋势,提示整体或成分方向选择性可能并非细胞的固有特性,而是可以随刺激取向因素的变化而改变的。     

Gait events during turning can be detected using kinematic features originally proposed for the analysis of straight-line walking

There is a growing interest for turning biomechanics notably because it is a more challenging task than straight-line walking during which some gait impairments are increased. Detecting heel-strike (HS) and toe-off (TO) events using the trajectory of markers attached to the feet is common in straight-line gait analysis and could reveal very useful to evaluate turning maneuvers. Yet, a comprehensive evaluation is missing, making difficult the selection of features for temporal analysis of turning. This study aimed to compare features of foot marker trajectories to detect HS and TO. Twenty healthy participants, 10 young (5 males, 23 ± 1 years old, 21.3 ± 2.2 kg/m²) and 10 elderly (4 males, 72 ± 5 years old, 26.4 ± 6.4 kg/m²), performed quarter, half, and full turns as well as straight-line walking in a gait lab. Fourteen features, adapted from straight-line walking literature, were used to detect HS and TO based on marker trajectories. Force plate measures served as reference. One HS and one TO feature were found particularly suitable. Overall, they detected more than 99% of the 1788 events recorded, with accuracies and precisions of −3.9 ms and 9.0 ms for HS and −7.8 ms and 10.7 ms for TO, respectively. Differences in accuracy and precision were observed among walking conditions and groups, but remained small, generally below 4.0 ms. In conclusion, this study identified kinematic features that can be used to analyze both turning and straight-line walking. Further assessment could be necessary with pathologies inducing severe degradation of gait patterns.     

天香胶囊对晕动病模型大鼠前庭核NMDAR1信号通路的影响*

目的:观察天香胶囊对晕动病模型大鼠前庭核NMDAR1(N-甲基-D-天冬氨酸受体1,N-methyl-D-aspartate acid receptor 1)、P-CaMKⅡ (磷酸化钙调蛋白激酶Ⅱ-亚基,the phosphorylation of calmodulin protein kinase Ⅱ alpha subunit)、P-CREB(磷酸化cAMP反应元件结合蛋白,the phosphorylation of cAMP response element binding protein)表达的影响,探讨天香胶囊调节晕动病模型大鼠前庭核兴奋性的内在分子机制。方法:将36只雄性SD大鼠随机分为正常对照组、模型组、阳性药对照组(东莨菪碱)、天香胶囊低、中、高剂量组。灌胃预给药3天后,采用双轴旋转刺激法复制大鼠晕动病模型,通过Western blotting法检测各组大鼠前庭核NMDAR1、P-CaMKⅡ/CaMKⅡ、P-CREB/CREB的表达情况。结果:与正常组大鼠相比,模型组大鼠前庭核NMDAR1、P-CaMKⅡ、P-CREB蛋白表达水平显著增加;与模型组相比,中、高剂量天香胶囊可显著下调晕动病模型大鼠前庭核组织NMDAR1、P-CaMKⅡ、P-CREB蛋白表达。结论:天香胶囊可抑制晕动病模型大鼠前庭核NMDAR1信号通路的活化,这可能是其在治疗晕动病中降低前庭核兴奋性的内在分子机制之一。     

便携式上肢运动协调性检测系统设计与实现

目的:研究人体上肢协调性运动的相关指标,以此来检测儿童先天性发育不良以及预防老年人的协调性相关疾病等问题。方法:本文设计了一种上肢协调性运动检测系统,检测被试的上肢运动状态,研究其协调性运动指标。本系统由运动感知单元、PC机端的控制台以及协调性运动指标数据分析组成。结果:利用该系统检测被试的运动协调性,给出了被试的准确性运动指标0.23以及协同性运动指标0.18。结论:经试验该系统对检测上肢的运动协调性有帮助,且方便携带与操作。     

Modeling spatial integration in the ocular following response using a probabilistic framework

The machinery behind the visual perception of motion and the subsequent sensori-motor transformation, such as in ocular following response (OFR), is confronted to uncertainties which are efficiently resolved in the primate's visual system. We may understand this response as an ideal observer in a probabilistic framework by using Bayesian theory [Weiss, Y., Simoncelli, E.P., Adelson, E.H., 2002. Motion illusions as optimal percepts. Nature Neuroscience, 5(6), 598-604, doi:10.1038/nn858] which we previously proved to be successfully adapted to model the OFR for different levels of noise with full field gratings. More recent experiments of OFR have used disk gratings and bipartite stimuli which are optimized to study the dynamics of center-surround integration. We quantified two main characteristics of the spatial integration of motion: (i) a finite optimal stimulus size for driving OFR, surrounded by an antagonistic modulation and (ii) a direction selective suppressive effect of the surround on the contrast gain control of the central stimuli [Barthélemy, F.V., Vanzetta, I., Masson, G.S., 2006. Behavioral receptive field for ocular following in humans: dynamics of spatial summation and center-surround interactions. Journal of Neurophysiology, (95), 3712-3726, doi:10.1152/jn.00112.2006]. Herein, we extended the ideal observer model to simulate the spatial integration of the different local motion cues within a probabilistic representation. We present analytical results which show that the hypothesis of independence of local measures can describe the spatial integration of the motion signal. Within this framework, we successfully accounted for the contrast gain control mechanisms observed in the behavioral data for center-surround stimuli. However, another inhibitory mechanism had to be added to account for suppressive effects of the surround.     

Four-dimensional model of the lower extremity after total hip arthroplasty

We have developed a four-dimensional (4D) model of the lower extremities after total hip arthroplasty in patients. The model can aid in preventing complications such as dislocation and wearing of the sliding surface. The skeletal structure and implant alignment were obtained from CT data. We applied registration method using CAD data to estimate accurate implant alignment from scattered CT data. The reconstructed three-dimensional (3D) skeletal model was combined with motion capture data that were acquired by an optical tracking system. We displayed the patient's skeletal movement and analyzed several parameters that relate to complications. The patient's skeletal model was superimposed onto video footage that was taken by a synchronized and calibrated digital video camera. For validation of the measurement error in this system, we used open MRI to evaluate the relative movement between skin markers and bones. This system visually represents not only the 3D anatomical structure, but also 4D dynamic functions that include the time sequential transitions of components and their positions. The open MRI results indicated that the average error in hip angle was within 5° for each static posture. This system enables clinicians to analyze patient's motions on the basis of individual differences. We found that our system was an effective tool in providing precise guidance of daily postoperative motions that was individualized for each patient. This system will be applicable for surgical planning, assessment of postoperative activities, and the development of new surgical techniques, materials, and prosthetic designs.