Cerebellar involvement in the coordination control of the oculo-manual tracking system: effects of cerebellar dentate nucleus lesion

Summary When the hand of the observer is used as a visual target, oculomotor performance evaluated in terms of tracking accuracy, delay and maximal ocular velocity is higher than when the subject tracks a visual target presented on a screen. The coordination control exerted by the motor system of the arm on the oculomotor system has two sources: the transfer of kinaesthetic information originating in the arm which increases the mutual coupling between the arm and the eyes and information from the arm movement efferent copy which synchronizes the motor activities of both subsystems (Gauthier et al. 1988; Gauthier and Mussa-Ivaldi 1988). We investigated the involvement of the cerebellum in coordination control during a visuo-oculo-manual tracking task. Experiments were conducted on baboons trained to track visual targets with the eyes and/or the hand. The role of the cerebellum was determined by comparing tracking performance defined in terms of delay, accuracy (position or velocity tracking errors) and maximal velocity, before and after lesioning the cerebellar dentate nucleus. Results showed that in the intact animal, ocular tracking was more saccadic when the monkey followed an external target than when it moved the target with its hand. After lesioning, eye-alone tracking of a visual target as well as eye-and-hand-tracking with the hand contralateral to the lesion was little if at all affected. Conversely, ocular tracking of the hand ipsilateral to the lesion side became more saccadic and the correlation between eye and hand movement decreased considerably while the delay between target and eyes increased. In normal animals, the delay between the eyes and the hand was close to zero, and maximal smooth pursuit velocity was around 100 degrees per second with close to unity gain; in eye-alone tracking the delay and maximal smooth pursuit velocity were 200 ms and 50 deg per second, respectively. After lesioning, delay and maximum velocity were respecttively around 210 ms and 40 deg per second, that is close to the values measured in eye-alone tracking. Thus, after dentate lesioning, the oculomotor system was unable to use information from the motor system of the arm to enhance its performance. We conclude that the cerebellum is involved in the coordination control between the oculomotor and manual motor systems in visuo-oculo-manual tracking tasks.     

计算机辅助全膝置换中股骨力线定位精度的实验研究

摘要利用光学定位追踪仪确定全膝置换中患者的股骨头中心从而确定其股骨力线，在力线的定位精度分析中，首次采用股骨的三维重建模型进行精度校验。实验结果表明通过追踪固定于股骨末端的刚性定位器即能确定精确的股骨力线，与传统的髓内定位相比，不仅可重复性好，而且大大地提高了术中股骨力线的位置精度，将其位置偏差减小到10以内。     

心电信号预处理与心电信号分析

本文介绍了在一种便携式心电监护仪器中是如何对心电数据进行预处理和智能分析的．为了适应便携式仪器的特征，我们在心电信号预处理中采用了FFT滤波和滑动平均滤波的方法去除各种干扰并使图像得以平滑，同时采用了差分阈值法提取特征点，考虑到监护仪器的实用性，在心电信号分析阶段，我们采用了分析特征间期异常情况的方法来替代对病症的智能诊断功能。     

Latency of adaptive vergence eye movements induced by vergence-vestibular interaction training in monkeys

Clear vision of objects that move in depth toward or away from an observer requires vergence eye movements. The vergence system must interact with the vestibular system to maintain the object images on the foveae of both eyes during head movement. Previous studies have shown that training with sinusoidal vergence-vestibular interaction improves the frequency response of vergence eye movements during pitch rotation: vergence eye velocity gains increase and phase-lags decrease. To further understand the changes in eye movement responses in this adaptation, we examined latencies of vergence eye movements before and after vergence-vestibular training. Two head-stabilized Japanese monkeys were rewarded for tracking a target spot moving in depth that required vergence eye movements of 10°/s. This target motion was synchronized with pitch rotation at 20°/s. Both target and chair moved in a trapezoidal waveform interspersed with random inter-trial intervals. Before training, pitch rotation in complete darkness without a target did not induce vergence eye movements. Mean latencies of convergence and divergence eye movements induced by vergence target motion alone were 182 and 169 ms, respectively. After training, mean latencies of convergence and divergence eye movements to a target synchronized with pitch rotation shortened to 65 and 53 ms, and vergence eye velocity gains (relative to vergence target velocity) at the normal latencies were 0.68 and 1.53, respectively. Pitch rotation alone without a target induced vergence eye movements with similar latencies after training. These results indicate that vestibular information can be used effectively to initiate vergence eye movements following vergence-vestibular training.     

Development of oculomotor functioning in preadolescence, adolescence, and adulthood

We examined developmental differences in smooth pursuit eye tracking proficiency in a large sample of preadolescent, adolescent, and adult males. Smooth pursuit was quantified using general measures of oculomotor functioning and by examining the frequency and dynamic characteristics of specific saccadic events. Examination of age effects using general measures indicated that, by late adolescence, the smooth pursuit system reached adult levels of functioning. No significant differences were found between the adolescent and adult groups on most global measures. However, both groups had better eye tracking than the preadolescent group, suggesting that during preadolescence the oculomotor system is still developing and is not yet capable of optimal performance. Examination of the frequency and dynamic characteristics of the saccadic events yielded additional information regarding the nature of the smooth pursuit eye tracking differences of the three age groups.     

Encoding of target direction and speed during visual instruction and arm tracking in dorsal premotor and primary motor cortical neurons

The encoding of direction and speed in the discharge of dorsal premotor (PMd) and primary motor (MI) neurons was studied during two-dimensional visually-instructed pursuit arm movements in which eight directions and four constant speeds were independently manipulated. Each trial consisted of equal durations of visual observation of target movement without hand movement (cue) and visual pursuit-tracking of the target with the hand (track). A total of 240 neurons was recorded from PMd and MI in two Macaca mulatta monkeys. Two classes of regression analyses were used to relate neuronal firing during the cue and track periods to direction and speed. First, the average firing from each period was fitted to target direction or speed. Period-averaged firing significantly correlated with direction more frequently in the track than in the cue period. Conversely, correlations with speed (with or without direction) were more common in the cue than in the track period. Secondly, a binwise regression evaluated the temporal evolution of firing correlations with direction and speed. Supporting the period-based results, significant binwise correlations of the discharge with speed occurred preferentially during the cue period when there was no hand movement. Prior to movement, correlations of the firing with direction became significant and continued through the movement. Both analyses demonstrated a distinct tendency for neurons to be modulated by speed information early and by direction information later. This temporal parcellation reflects both the sequential demands of the task and constraints placed on the neural computations. The early representation of target speed is hypothesized to reflect the need to calculate a 'go signal' for the initiation of movement.     

青年人急性心肌梗死的特点及预防

目的：探讨青年人急性心肌梗死的特点及预防。方法：对28例青年人（≤40岁）心肌梗死的临床资料进行分析。结果：本组男性26例，占92．9％；7-9月份发病16例，占57％；体力劳动者22例，占78．6％；有明显冠心病危险因素者28例，占89．3％；发病前有诱发因素者23例，占82．1％。结论：青年人心肌梗死具有男性多见、夏季多见、体力劳动者多见、危险因素多明显、诱发因素多突出、先兆少、症状多典型等特点。其发生多与不良生活方式有关。加强健康教育，建立良好的生活方式是预防青年人心肌梗死的关键。     

两种对精神分裂症患者检查方法对比分析

目的：探讨精神分裂症患者探究性眼球轨迹运动与事件相关电位P300的相关性及其差异性。方法：对50例精神分裂症患者分别使用眼球轨迹运动检查仪和事件相关电位检查仪进行测试。结果：50例精神分裂症患者D分值为正分;而P300潜伏期延长则与症状相关。结论：眼球轨迹运动和事件相关电位作为对精神分裂症患者的检测,前者有助于临床辅助诊断,后者则有助于精神分裂症患者病理心理研究和疗效的判断。     

度量关联规则在医院消毒供应质量追踪管理中的研究

目的:探讨基于度量关联规则的质量追踪模式在医院消毒供应管理中的应用价值.方法:采用基于度量关联规则的质量追踪模式进行医院消毒供应质量追踪管理.选取医院消毒供应中心的600件无菌器械,按照管理模式的不同将其分为观察组和对照组,每组300件;同期另选使用该无菌器械的200例患者,每组100例.观察组采用质量追踪式管理,对照...