Cerebellar subjects show impaired adaptation of anticipatory EMG during catching
Cerebellar subjects show impaired adaptation of anticipatory EMG during catching
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DOI：
10.1152/jn.1999.82.5.2108
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发表时间：
1999-11-01
影响因子：
2.5
通讯作者：
Bastian, AJ
中科院分区：
文献类型：
--
作者：
Lang, CE;Bastian, AJ
我们评估的作用，小脑在适应预期的肌肉活动在多关节捕捉任务。有和没有小脑损伤的人抓住了一系列从上面掉下来的不同重量的球。在实验I（轻-重-轻）中，每个受试者被要求抓住轻球（基线阶段），重球（适应阶段），然后轻球再次（后适应阶段）。受试者没有被告知球什么时候会被交换，他们被要求在接球过程中将手保持在垂直的空间“窗口”内。在一系列的试验中，我们测量了三维（3-D）的位置和肌电图（EMG）从捕捉arm. We建模的适应过程中使用的指数衰减函数，这个模型使我们能够分离的性能变异的适应。从位置数据的结果表明，小脑受试者不适应或适应非常缓慢，以改变球的重量时，与对照组相比。小脑组需要平均30.9 +/- 8.7次试验（平均值+/- SE）才能通过适应过程的三分之二，而对照组需要1.7 +/- 0.2次试验。只有对照组显示出负的后效，表明存储的适应。两组之间的性能变异性无差异。EMG数据显示，控制受试者增加了手臂屈肌的预期肌肉活动，以控制球在撞击时的动量。小脑受试者无法有区别地增加三个关节的预期肌肉活动，以成功地执行任务。在实验2（重-轻-重）中，我们测试了当适应轻球和重球时，适应率是否改变。受试者抓住重球（基线阶段），轻球（适应阶段），然后重球再次（适应后阶段）。实验一和实验二的适应率比较表明，无论是适应轻球还是适应重球，适应率都没有变化。鉴于这些发现，我们得出结论，小脑是重要的，在产生适当的预期肌肉活动在多个肌肉和修改它，以响应不断变化的需求，通过试错练习。
We evaluated the role of the cerebellum in adapting anticipatory muscle activity during a multijointed catching task. Individuals with and without cerebellar damage caught a series of balls of different weights dropped from above. In Experiment I (light-heavy-light), each subject was required to catch light balls (baseline phase), heavy balls (adaptation phase), and then light balls again (postadaptation phase). Subjects were not told when the balls would be switched, and they were required to keep their hand within a vertical spatial "window" during the catch. During the series of trials, we measured three-dimensional (3-D) position and electromyogram (EMG) from the catching arm. We modeled the adaptation process using an exponential decay function; this model allowed us to dissociate adaptation from performance variability. Results from the position data show that cerebellar subjects did not adapt or adapted very slowly to the changed ball weight when compared with the control subjects. The cerebellar group required an average of 30.9 +/- 8.7 trials (mean +/- SE) to progress approximately two-thirds of the way through the adaptation compared with 1.7 +/- 0.2 trials for the control group. Only control subjects showed a negative aftereffect indicating storage of the adaptation. No difference in performance variability existed between the two groups. EMG data show that control subjects increased their anticipatory muscle activity in the flexor muscles of the arm to control the momentum of the ball at impact. Cerebellar subjects were unable to differentially increase the anticipatory muscle activity across three joints to perform the task successfully. In Experiment 2 (heavy-light-heavy), we tested to see whether the rate of adaptation changed when adapting to a light ball versus a heavy ball. Subjects caught the heavy balls (baseline phase), the light balls (adaptation phase), and then heavy balls again (postadaptation phase). Comparison of rates of adaptation between Experiment I and Experiment 2 showed that the rate of adaptation was unchanged whether adapting to a light ball or a heavy ball. Given these findings, we conclude that the cerebellum is important in generating the appropriate anticipatory muscle activity across multiple muscles and modifying it in response to changing demands though trial-and-error practice.