Jueptner M, Frith C D, Brooks D J, Frackowiak R S, Passingham R E
Wellcome Department of Cognitive Neurology, Institute of Neurology, London, United Kingdom.
J Neurophysiol. 1997 Mar;77(3):1325-37. doi: 10.1152/jn.1997.77.3.1325.
We used positron emission tomography to study motor learning by trial and error. Subjects learned sequences of eight finger movements. Tones generated by a computer told the subjects whether any particular move was correct or incorrect. A control condition was used in which the subjects generated moves, but there was no feedback to indicate success or failure, and so on learning occurred. In this condition (free selection) the subjects were required to make a finger movement on each trial and to vary the movements randomly over trials. The subjects had a free choice of which finger to move on any one trial. On this task there was no systematic change in responses over trials and no change in the response times. Two other conditions were included. In one the subjects repetitively moved the same finger on all trials and in a baseline condition the subjects heard the pacing tones and auditory feedback but made no movements. Comparing new learning with the free selection task, there was a small activation in the right prefrontal cortex. This may reflect the fact that in new learning, but not free selection, the subject rehearse past moves and adapt their responses accordingly. The caudate nucleus was strongly activated during new learning. It is suggested that this activity may be related either to mental rehearsal or to reinforcement of the movements as a consequence of the outcomes. The putamen was activated anteriorly on the free selection task and more posteriorly when the subjects repetitively made the same movement. It is suggested that the differences in the location of the peak activation in the striatum may represent the operation of different corticostriatal loops. The cerebellar nuclei (bilaterally) and vermis were more active in the new learning condition than during the performance of the free selection task. There was no difference in the activation of the cerebellum when the free selection task was compared with repetitive performance of the same movement. We tentatively suggest that the basal ganglia may be involved in the specification of movement on the basis of memory of either the movements or the outcomes, but that the cerebellum may be more directly involved in changes in the parameters of movement execution.
我们使用正电子发射断层扫描技术，通过试错法来研究运动学习。受试者学习由八个手指动作组成的序列。计算机发出的音调会告知受试者某个特定动作是否正确。我们设置了一个对照条件，即受试者做出动作，但没有反馈表明动作成功或失败，因此没有发生学习。在这种条件下（自由选择），要求受试者在每次试验中做出一个手指动作，并在不同试验中随机改变动作。受试者在任何一次试验中可以自由选择移动哪根手指。在这项任务中，受试者的反应在不同试验中没有系统性变化，反应时间也没有改变。还包括另外两种条件。一种是受试者在所有试验中重复移动同一根手指，另一种是在基线条件下，受试者听到节拍音调及听觉反馈，但不做动作。将新学习与自由选择任务进行比较时，右侧前额叶皮质有轻微激活。这可能反映了这样一个事实，即在新学习中，而不是自由选择中，受试者会回顾过去的动作并相应地调整他们的反应。在新学习过程中，尾状核被强烈激活。有人认为，这种活动可能与心理演练有关，或者与因结果而对动作的强化有关。壳核在自由选择任务中前部被激活，而当受试者重复做出相同动作时，壳核后部被激活。有人认为，纹状体中峰值激活位置的差异可能代表了不同皮质纹状体回路的运作。在新学习条件下，小脑核（双侧）和小脑蚓部比在自由选择任务执行期间更活跃。将自由选择任务与相同动作的重复执行进行比较时，小脑的激活没有差异。我们初步认为，基底神经节可能基于动作或结果的记忆参与动作的指定，但小脑可能更直接地参与运动执行参数的变化。
