Karni A, Meyer G, Jezzard P, Adams M M, Turner R, Ungerleider L G
Laboratory of Neuropsychology, NIMH, National Institutes of Health, Bethesda, Maryland 20892, USA.
Nature. 1995 Sep 14;377(6545):155-8. doi: 10.1038/377155a0.
Performance of complex motor tasks, such as rapid sequences of finger movements, can be improved in terms of speed and accuracy over several weeks by daily practice sessions. This improvement does not generalize to a matched sequence of identical component movements, nor to the contralateral hand. Here we report a study of the neural changes underlying this learning using functional magnetic resonance imaging (MRI) of local blood oxygenation level-dependent (BOLD) signals evoked in primary motor cortex (M1). Before training, a comparable extent of M1 was activated by both sequences. However, two ordering effects were observed: repeating a sequence within a brief time window initially resulted in a smaller area of activation (habituation), but later in larger area of activation (enhancement), suggesting a switch in M1 processing mode within the first session (fast learning). By week 4 of training, concurrent with asymptotic performance, the extent of cortex activated by the practised sequence enlarged compared with the unpractised sequence, irrespective of order (slow learning). These changes persisted for several months. The results suggest a slowly evolving, long-term, experience-dependent reorganization of the adult M1, which may underlie the acquisition and retention of the motor skill.
诸如快速的手指运动序列等复杂运动任务的表现，通过每日的练习课程，在速度和准确性方面可在数周内得到改善。这种改善不会推广到匹配的相同组成动作序列，也不会推广到对侧手。在此，我们报告一项利用功能磁共振成像（MRI）对初级运动皮层（M1）中诱发的局部血氧水平依赖（BOLD）信号进行研究，以探究这种学习背后的神经变化。在训练前，两个序列激活的M1范围相当。然而，观察到两种排序效应：在短时间窗口内重复一个序列最初会导致激活面积较小（习惯化），但随后会导致激活面积较大（增强），这表明在第一阶段M1处理模式发生了转变（快速学习）。到训练第4周时，与渐近表现同时出现的是，与未练习序列相比，练习序列激活的皮层范围扩大，且与顺序无关（缓慢学习）。这些变化持续了数月。结果表明，成年M1存在缓慢演变、长期的、依赖经验的重组，这可能是运动技能习得和保持的基础。
