Jueptner M, Weiller C
Department of Psychiatry, University Clinics, Essen, Germany.
Brain. 1998 Aug;121 ( Pt 8):1437-49. doi: 10.1093/brain/121.8.1437.
The role of the basal ganglia and cerebellum in the control of movements is unclear. We summarize results from three groups of PET studies of regional CBF. The results show a double dissociation between (i) selection of movements, which induces differential effects in the basal ganglia but not the cerebellum, and (ii) sensory information processing, which involves the cerebellum but not the basal ganglia. The first set of studies concerned motor learning of a sequence of finger movements; there was a shift of activation in the anterior-posterior direction of the basal ganglia which paralleled changes in the motor areas of the frontal cortex. During new learning, the dorsolateral prefrontal cortex and striatum (caudate nucleus and anterior putamen) were activated. When subjects had to select movements, the premotor cortex and mid-putamen were activated. With automatic (overlearned) movements, the sensorimotor cortex and posterior putamen were activated. When subjects paid attention to overlearned actions, activation shifted back to the dorsolateral prefrontal cortex and striatum. The cerebellum was not activated when subjects made new decisions, attended to their actions or selected movements. These results demonstrate components of basal ganglia-(thalamo)-cortical loops in humans. According to earlier studies in animals we propose that the basal ganglia may be concerned with selecting movements or the selection of appropriate muscles to perform a movement selected by cortical areas (e.g. premotor cortex). Secondly, a visuomotor co-ordination task was examined. In the absence of visual control over arm movements, subjects were required to use a computer mouse to either generate new lines or to re-trace lines on a computer screen. The neocerebellum (hemispheres of the posterior lobe, cerebellar nuclei and cerebellar vermis), not the basal ganglia, was more engaged when lines were re-traced (compared with new line generation). Animal experiments have shown that error detection (deviation from given lines) and correction occurs during line re-tracing but not line generation. Our data suggest that the neocerebellum (not the basal ganglia) is involved in monitoring and optimizing movements using sensory (proprioceptive) feedback. Thirdly, the relative contribution of sensory information processing to the signal during active/passive execution of a motor task (flexion and extension of the elbow) was examined; it was found that 80-90% of the neocerebellar signal could be attributed to sensory information processing. The basal ganglia were not involved in sensory information processing. They may be concerned with movement/ muscle selection (efferent motor component); the neocerebellum may be concerned with monitoring the outcome (afferent sensory component) and optimizing movements using sensory (feedback) information.
基底神经节和小脑在运动控制中的作用尚不清楚。我们总结了三组关于局部脑血流量（CBF）的正电子发射断层扫描（PET）研究结果。结果显示出双重分离：（i）运动选择，这在基底神经节中会引发不同效应，但在小脑中不会；（ii）感觉信息处理，这涉及小脑但不涉及基底神经节。第一组研究关注一系列手指运动的运动学习；基底神经节在前后方向上的激活发生了变化，这与额叶皮质运动区的变化平行。在新学习过程中，背外侧前额叶皮质和纹状体（尾状核和壳核前部）被激活。当受试者必须选择运动时，运动前皮质和壳核中部被激活。对于自动（过度学习）的运动，感觉运动皮质和壳核后部被激活。当受试者关注过度学习的动作时，激活又回到背外侧前额叶皮质和纹状体。当受试者做出新决策、关注自己的动作或选择运动时，小脑未被激活。这些结果证明了人类基底神经节 -（丘脑）- 皮质环路的组成部分。根据早期对动物的研究，我们提出基底神经节可能与选择运动或选择合适的肌肉以执行由皮质区域（如运动前皮质）选择的运动有关。其次，研究了一个视觉运动协调任务。在对手臂运动缺乏视觉控制的情况下，要求受试者使用电脑鼠标在电脑屏幕上绘制新线条或重新描绘线条。当重新描绘线条时（与绘制新线条相比），新小脑（后叶半球、小脑核和小脑蚓部）比基底神经节更活跃。动物实验表明，在重新描绘线条过程中会进行错误检测（与给定线条的偏差）和校正，但在绘制新线条时不会。我们的数据表明，新小脑（而非基底神经节）参与利用感觉（本体感觉）反馈监测和优化运动。第三，研究了在主动/被动执行运动任务（肘部屈伸）期间感觉信息处理对信号的相对贡献；发现新小脑信号的80 - 90%可归因于感觉信息处理。基底神经节不参与感觉信息处理。它们可能与运动/肌肉选择（传出运动成分）有关；新小脑可能与监测结果（传入感觉成分）以及利用感觉（反馈）信息优化运动有关。
