Molina-Luna Katiuska, Hertler Benjamin, Buitrago Manuel M, Luft Andreas R
Department of General Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Hoppe-Seyler-Str. 3, 72076 Tübingen, Germany.
Neuroimage. 2008 May 1;40(4):1748-54. doi: 10.1016/j.neuroimage.2007.11.018. Epub 2007 Nov 28.
Learning a complex motor skill is associated with changes in motor cortex representations of trained body parts. It has been suggested that representation changes reflect the storage of a skill, i.e., the motor memory trace. If a reflection of the trace, such modifications should persist after training is stopped for as long as the skill is retained. The objective here was to test the persistence of learning-related changes in the representation of the forelimb of the rat after learning a reaching task using repeated epidural stimulation mapping of primary motor cortex. It is shown that the forelimb representations enlarge after 8 days of training (n=8) but contract while performing arm movements without learning (n=7, p=0.006); hindlimb representations remain unchanged. Enlargement correlated with learning success (r=0.82; p=0.012). Subsequently, after 8 days without training, representation size reverted to baseline while the motor skill was retained. Somatotopy remained unaltered by a second training phase in which performance did not improve further (n=5). These findings suggest that successful acquisition but not storage of a motor skill depends on cortical map changes. The motor memory trace in rats may require changes in motor cortex organization other than those detected by stimulation mapping.
学习复杂的运动技能与训练身体部位的运动皮层表征变化有关。有人提出，表征变化反映了技能的存储，即运动记忆痕迹。如果是痕迹的反映，那么只要技能得以保留，这种改变在训练停止后就应该持续存在。这里的目的是通过对大鼠初级运动皮层进行重复硬膜外刺激映射，来测试在大鼠学习抓握任务后，前肢表征中与学习相关的变化的持续性。结果显示，训练8天后（n = 8）前肢表征扩大，但在不进行学习的情况下进行手臂运动时（n = 7，p = 0.006）前肢表征缩小；后肢表征保持不变。扩大与学习成功相关（r = 0.82；p = 0.012）。随后，在没有训练的8天后，尽管运动技能得以保留，但表征大小恢复到了基线水平。在第二个训练阶段，表现没有进一步提高（n = 5），躯体定位并未改变。这些发现表明，运动技能的成功习得而非存储取决于皮层图谱的变化。大鼠的运动记忆痕迹可能需要运动皮层组织发生除刺激映射所检测到的变化之外的其他变化。
