Basal ganglia network mediates the control of movement amplitude
Basal ganglia network mediates the control of movement amplitude
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DOI：
10.1007/s00221-003-1593-3
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发表时间：
2003-11-01
影响因子：
2
通讯作者：
Turner, RS
中科院分区：
文献类型：
--
作者：
Desmurget, M;Grafton, ST;Turner, RS
在本研究中，我们解决的假设，基底神经节是专门参与规划的运动幅度（或相关的协变量）。这种预测通常是基于帕金森病（PD）患者表现出运动功能减退的观察而提出的。然而，对文献的仔细检查表明，这种常见的临床症状并不总是与实验观察相呼应。当需要指出的视觉目标的情况下，移动肢体的视觉，PD科目表现出各种模式的不准确性，包括hypometria，hypermetria，系统的方向偏差，或方向依赖性的错误。他们甚至被证明与健康的、年龄匹配的受试者一样准确。本研究的主要目的是解决这些不一致的根源。为此，我们要求9名晚期PD患者和15名年龄匹配的对照受试者对视觉目标进行平面伸展运动。八个目标被呈现在以手的起始位置为中心的圆周围的等距方向上。基于先前验证的解析程序，端点错误被分割为定位和规划错误。定位误差是指在估计初始手位置时存在系统偏差。这些偏差可能会将纯幅度误差的简单模式转换为涉及幅度和方向误差的复杂模式。结果表明，PD患者和对照组的定位误差不同。这并不奇怪，因为PD患者的本体感觉发生了改变，即使在视觉可用的情况下，静止时定位手的能力也主要依赖于本体感觉。与正常受试者不同，PD中的定位错误是特异质的，在受试者之间缺乏一致的模式。当初始手定位误差的混杂效应被取消时，我们发现终点误差仅是由于实施了尺度不足的运动增益（15%），而没有方向偏差。有趣的是，发现下冲水平随着疾病的严重程度而增加（从统一帕金森病评定量表（Unified Parkinson's Disease Rating Scale，简称DMRS，motor score）推断）。我们还观察到，运动变异性被放大（32%），但仅沿着主要运动轴（范围变异性）。方向变异性在患者人群和对照组中没有显著差异。当考虑在一起，这些结果支持的想法，基底神经节是专门参与控制运动幅度（或一些协变量）。我们建议，这种结构参与范围规划，通过调节皮质活动和/或调谐的脊髓神经元间回路。
In the present study we address the hypothesis that the basal ganglia are specifically involved in the planning of movement amplitude (or related covariates). This prediction has often been put forward based on the observation that Parkinson's disease (PD) patients exhibit hypokinesia. A close examination of the literature shows, however, that this commonly reported clinical symptom is not consistently echoed by experimental observations. When required to point to visual targets in the absence of vision of the moving limb, PD subjects exhibit various patterns of inaccuracy, including hypometria, hypermetria, systematic direction bias, or direction-dependent errors. They have even been shown to be as accurate as healthy, age-matched subjects. The main aim of the current study is to address the origin of these inconsistencies. To this end, we required nine patients presenting with advanced PD and 15 age-matched control subjects to perform planar reaching movements to visual targets. Eight targets were presented in equally spaced directions around a circle centered on the hand's starting location. Based on a previously validated parsing procedure, end-point errors were segmented into localization and planning errors. Localization errors refer to the existence of systematic biases in the estimation of the initial hand location. These biases can potentially transform a simple pattern of pure amplitude errors into a complex pattern involving both amplitude and direction errors. Results indicated that localization errors were different in the PD patients and the control subjects. This is not surprising knowing both that proprioception is altered in PD patients and that the ability to locate the hand at rest relies mainly on the proprioceptive sense, even when vision is available. Unlike normal subjects, localization errors in PD were idiosyncratic, lacking a consistent pattern across subjects. When the confounding effect of initial hand localization errors was canceled, we found that end-point errors were only due to the implementation of an underscaled movement gain (15%), without direction bias. Interestingly, the level of undershoot was found to increase with the severity of the disease (inferred from the Unified Parkinson's Disease Rating Scale, UPDRS, motor score). We also observed that movement variability was amplified (32%), but only along the main movement axis (extent variability). Direction variability was not significantly different in the patient population and the control group. When considered together, these results support the idea that the basal ganglia are specifically involved in the control of movement amplitude (or of some covariates). We propose that this structure participates in extent planning by modulating cortical activity and/or the tuning of the spinal interneuronal circuits.