Functional coupling of the stabilizing eye and head reflexes during horizontal and vertical linear motion in the cat

Summary The otolith contribution and otolith-visual interaction in eye and head stabilization were investigated in alert cats submitted to sinusoidal linear accelerations in three defined directions of space: up-down (Z motion), left-right (Y motion), and forward-back (X motion). Otolith stimulation alone was performed in total darkness with stimulus frequency varying from 0.05 to 1.39 Hz at a constant half peak-to-peak amplitude of 0.145 m (corresponding acceleration range 0.0014–1.13 g) Optokinetic stimuli were provided by sinusoidally moving a pseudorandom visual pattern in the Z and Y directions, using a similar half peak-to-peak amplitude (0.145 m, i.e., 16.1°) in the 0.025–1.39 Hz frequency domain (corresponding velocity range 2.5°–141°/s). Congruent otolith-visual interaction (costimulation, CS) was produced by moving the cat in front of the earth-stationary visual pattern, while conflicting interaction was obtained by suppressing all visual motion cues during linear motion (visual stabilization method, VS, with cat and visual pattern moving together, in phase). Electromyographic (EMG) activity of antagonist neck extensor (splenius capitis) and flexor (longus capitis) muscles as well as horizontal and vertical eye movements (electrooculography, EOG) were recorded in these different experimental conditions. Results showed that otolith-neck (ONR) and otolith-ocular (OOR) responses were produced during pure otolith stimulation with relatively weak stimuli (0.036 g) in all directions tested. Both EMG and EOG response gain slightly increased, while response phase lead decreased (with respect to stimulus velocity) as stimulus frequency increased in the range 0.25–1.39 Hz. Otolith contribution to compensatory eye and neck responses increased with stimulus frequency, leading to EMG and EOG responses, which oppose the imposed displacement more and more. But the otolith system alone remained unable to produce perfect compensatory responses, even at the highest frequency tested. In contrast, optokinetic stimuli in the Z and Y directions evoked consistent and compensatory eye movement responses (OKR) in a lower frequency range (0.025–0.25 Hz). Increasing stimulus frequency induced strong gain reduction and phase lag. Oculo-neck coupling or eye-head synergy was found during optokinetic stimulation in the Z and Y directions. It was characterized by bilateral activation of neck extensors and flexors during upward and downward eye movements, respectively, and by ipsilateral activation of neck muscles during horizontal eye movements. These visually-induced neck responses seemed related to eye velocity signals. Dynamic properties of neck and eye responses were significantly improved when both inputs were combined (CS). Near perfect compensatory eye movement and neck muscle responses closely related to stimulus velocity were observed over all frequencies tested, in the three directions defined. The present study indicates that eye-head coordination processes during linear motion are mainly dependent on the visual system at low frequencies (below 0.25 Hz), with close functional coupling of OKR and eye-head synergy. The otolith system basically works at higher stimulus frequencies and triggers Synergist OOR and ONR. However, both sensorimotor subsystems combine their dynamic properties to provide better eyehead coordination in an extended frequency range and, as evidenced under VS condition, visual and otolith inputs also contribute to eye and neck responses at high and low frequency, respectively. These general laws on functional coupling of the eye and head stabilizing reflexes during linear motion are valid in the three directions tested, even though the relative weight of visual and otolith inputs may vary according to motion direction and/or kinematics.     

Reduction and stabilization of lumbar and thoracolumbar spine fractures with Louis' plates and internal fixator: a comparative study

Summary In this retrospective study, 28 patients who presented isolated fractures from T11 to L4 were surgically treated using a posterior approach. The fractures were reduced and stabilized in half of the cases with Louis' plates and in the other half with an internal fixator. Twelve patients had partial neurological deficits on admission. They were reviewed after a mean period of 24 months from time of injury, and 10 months after implant removal. The kyphosis of the fractured vertebral body was measured, and showed a mean value of 18° before surgery and 10.3° at the last visit. The regional statics of the spine were also studied. The residual mobility of the fixated and neighbouring spinal units was assessed, comparing long segment fixation (plates) with short segment fixation (internal fixator). The residual mobility of the adjacent, non-fixed segments was significantly better when the internal fixator had been used than with the Louis' plates. Of the 12 patients with neurological involvement, 11 had increased their Frankel score by one grade. Results were evaluated by clinical parameters (pain, neurological deficit, occupational disability); scores were as follows: 32% good, 57% satisfactory and 11% poor. There was no significant difference in clinical score between the two treatment modalities.     

The human motion onset VEP as a function of stimulation area for foveal and peripheral vision

We studied amplitude of the wave N200 of the motion-onset VEP by varying the side length of a square stimulation field between 0.5 and 7 degrees. A significant increase in amplitude was obtained between 0.5 and 1 degree of side length in central stimulation and between 0.5 and 5 degrees in 10-degree peripheral stimulation. Variations of spatial frequency between 0.34 and 6.8 c/deg did not modify the amplitude size, ie, no tuning effect could be found. The results of simultaneous and separate stimulation of foveal and parafoveal regions support the observation that the stimulation field size is a minor influence. Features of motion-sensitive cortical neurons, such as those found in monkeys, could account for this behavior.     

Brain activation associated with visual motion studied by functional magnetic resonance imaging in humans

Localized brain activation in response to moving visual stimuli was studied by functional magnetic resonance imaging (fMRI). Stimuli were 100 small white dots randomly arranged on a visual display. During the Motion condition, the dots moved along random, noncoherent linear trajectories at different velocities. During the Blink condition, the dots remained stationary but blinked on and off every 500 ms. The Motion and Blink conditions continuously alternated with 10 cycles per run and 6–8 runs per experiment. In half of the runs, the starting stimulus condition was Motion, while in the remaining runs it was Blink. A series of 128 gradient echo echoplanar images were acquired from 5–7 slices during each run using a 1.5 T GE Signa with an Advanced NMR echoplanar subsystem. The time series for each voxel were analyzed in the frequency domain. Voxels which demonstrated a significant spectral peak at the alternation frequency and whose phase changed in response to stimulus order were considered activated. These activated voxels were displayed upon high resolution anatomical images to determine the sites of activation and were also transformed into the coordinates of Talairach and Tournoux ([1988] Co-planar Stereotaxic Atlas of the Human Brain, New York: Thieme) for comparison to prior neuroimaging studies. Seven of ten subjects showed clusters of activation bilaterally at the junction of the temporal and occipital lobes (area 37) in response to moving stimuli. Most activated voxels were located within or adjacent to a region designated the parietal-temporal-occipital fossa, or PTOF. Five subjects also showed activation to moving stimuli in midline occipital cortex. The activated voxels in midline cortex had a significantly shorter phase delay in their MR signal change relative to voxels in PTOF. © 1995 Wiley-Liss, Inc. 1

1 This article is a US Government work and, as such, is in the public domain in the United States of America

     

目前下肢被动运动装置存在的问题和改进原则

本文分析了目前下肢ＣＰＭ装置存在的问题,指出在ＣＰＭ每一运动周期,人体下肢与ＣＰＭ支架之间都将产生有害的相对位移和交替牵拉应力,影响关节功能顺利康复。提出下肢ＣＰＭ的正确使用方法和设计原则。     

倒视与平行秋千诱发运动病的比较

目的探讨倒视诱发运动病的特点。方法 １０名健康国性在间隔为５－７ｄ的不同日期分别进行戴两种倒视镜步行试验和平行秋千摆试验。观察倒视引起民平衡、倒视和平行秋千诱发运动病症状;计算被试者倒视刺激耐力指数（ＲＶＴＩ）和秋千刺激耐力指数（ＬＡＴＩ）,分别表示倒视和秋诱发运动病易感性。结果 步行倒视试验可引起明显的姿态失平衡和运动病症状,失平衡程度与运动病易感性有相关性。与秋千诱发运动病症状比较,倒视诱发运     

Daily CT localization for correcting portal errors in the treatment of prostate cancer

Introduction: Improved prostate localization techniques should allow the reduction of margins around the target to facilitate dose escalation in high-risk patients while minimizing the risk of normal tissue morbidity. A daily CT simulation technique is presented to assess setup variations in portal placement and organ motion for the treatment of localized prostate cancer.

Methods and Materials: Six patients who consented to this study underwent supine position CT simulation with an alpha cradle cast, intravenous contrast, and urethrogram. Patients received 46 Gy to the initial Planning Treatment Volume (PTV₁) in a four-field conformal technique that included the prostate, seminal vesicles, and lymph nodes as the Gross Tumor Volume (GTV₁). The prostate or prostate and seminal vesicles (GTV₂) then received 56 Gy to PTV₂. All doses were delivered in 2-Gy fractions.

After 5 weeks of treatment (50 Gy), a second CT simulation was performed. The alpha cradle was secured to a specially designed rigid sliding board. The prostate was contoured and a new isocenter was generated with appropriate surface markers. Prostate-only treatment portals for the final conedown (GTV₃) were created with a 0.25-cm margin from the GTV to PTV. On each subsequent treatment day, the patient was placed in his cast on the sliding board for a repeat CT simulation. The daily isocenter was recalculated in the anterior/posterior (A/P) and lateral dimension and compared to the 50-Gy CT simulation isocenter. Couch and surface marker shifts were calculated to produce portal alignment. To maintain proper positioning, the patients were transferred to a stretcher while on the sliding board in the cast and transported to the treatment room where they were then transferred to the treatment couch. The patients were then treated to the corrected isocenter. Portal films and electronic portal images were obtained for each field.

Results: Utilizing CT–CT image registration (fusion) of the daily and 50-Gy baseline CT scans, the isocenter changes were quantified to reflect the contribution of positional (surface marker shifts) error and absolute prostate motion relative to the bony pelvis. The maximum daily A/P shift was 7.3 mm. Motion was less than 5 mm in the remaining patients and the overall mean magnitude change was 2.9 mm. The overall variability was quantified by a pooled standard deviation of 1.7 mm. The maximum lateral shifts were less than 3 mm for all patients. With careful attention to patient positioning, maximal portal placement error was reduced to 3 mm.

Conclusion: In our experience, prostate motion after 50 Gy was significantly less than previously reported. This may reflect early physiologic changes due to radiation, which restrict prostate motion. This observation is being tested in a separate study. Intrapatient and overall population variance was minimal. With daily isocenter correction of setup and organ motion errors by CT imaging, PTV margins can be significantly reduced or eliminated. We believe this will facilitate further dose escalation in high-risk patients with minimal risk of increased morbidity. This technique may also be beneficial in low-risk patients by sparing more normal surrounding tissue.     

TTS-ST93-1穴位贴剂防治运动病的观察

目的 :确定合适的防治运动病的经络穴位 ,观察TTS -ST93 -1作为穴位贴剂的抗运动病作用。方法 :有近期晕车史的年青健康自愿者 1 63名 ,男性 ,乘卡车、装甲车 3h。采用随机分组、双盲实验方法。分为实验药物组 (TTS -ST93 -1贴剂膜片 ) ,阳性对照组 (TTS -Scop贴剂膜片 ) ,阴性对照组 (乳糖贴剂膜片 )。选择穴位 :内关、神阙、脉。实验药物组又分 :ST93 -1内关组 ,ST93 -1神阙组 ,ST93 -1脉组。按美国Graybiel制定的运动病症状数字评分法 ,评定被试者的晕车症状程度。结果 :ST93 -1贴剂的平均有效率为 95 9% ,与阴性对照组比较有显著性差异 (P <0 0 1 )。ST93 -1内关组的保护率为 45 5 % ,神阙组的保护率是81 4% ,脉组的保护率为 1 0 0 % ,平均保护率是 76 0 % ,与阳性对照组 (2 7 3 % )比较有显著性差异。ST93 -1贴剂引起的口干、嗜睡、困倦副作用的发生率与阴性对照组比较无显著性差异。被试者穴位上贴药 8h后 ,ST93 -1引起的皮肤红肿、痛、痒等过敏症状较轻。结论 :TTS -ST93 -1有效穴位贴剂是防治运动病的良好方法。     

The relationship between transverse plane leg rotation and transverse plane motion at the knee and hip during normal walking

The purpose of this study was to test the clinical hypothesis that the magnitude and temporal characteristics of rearfoot complex motion are closely correlated with those of the transverse plane motion at the knee and hip. Twenty subjects underwent kinematic assessment during walking at 108 steps/minute. The transverse plane rotation of the leg relative to the foot was used to indicate rearfoot complex pronation and supination. Taking into account errors inherent in kinematic assessment involving skin mounted markers, it is unlikely that a correlation exists between the range of internal leg rotation during the contact phase and the total range of transverse plane leg rotation during gait and the corresponding values for the transverse plane motion at the knee and hip. Correlation tests were performed to assess the temporal characteristics of the motions at the joints that showed that there was no correlation between the transverse plane motion in the rearfoot complex, knee and hip. Thus the hypothesis that the magnitude and temporal characteristics of rearfoot complex motion are closely correlated with the transverse plane motion at the knee and hip was rejected.     

应用体素内不相干运动扩散加权成像评价早期慢性移植肾肾病

目的：探讨应用体素内不相干运动扩散加权成像(intravoxel incoherent motion diffusion weighted imaging,IVIM-DWI)技术无创性评价早期慢性移植肾肾病(chronic allograft nephropathy,CAN)的可行性及临床应用价值。方法：收集符合本研究纳入标准的住院患者23例,其中经病理诊断为早期CAN的患者12例(CAN组),移植肾肾功能长期稳定的志愿者11例(对照组)。采用多b值DWI序列对移植肾进行磁共振扫描,利用IVIM2b_new软件获取移植肾的IVIM-DWI各定量参数伪彩图及测量肾实质的IVIM-DWI各定量参数值,包括真实扩散系数(D)、灌注相关扩散系数(D*)和灌注分数(f)。采用独立样本t检验对CAN组和对照组的IVIM各定量参数值进行比较,对差异具有统计学意义的指标进行ROC分析,并计算曲线下面积。结果：CAN组的定量参数D值低于对照组,差异具有统计学意义(P<0.05),两组间D*及f值的差异无统计学意义(P>0.05)。D值鉴别早期CAN的敏感度和特异度分别为58.3%和90.9%,曲线下面积为0.784。 结论：IVIM-DWI的定量参数D能在一定程度上无创性评价早期CAN。IVIM-DWI技术有望成为一种筛查早期CAN的简单有效的无创手段,以协助早期诊断与动态监测CAN。