Faculty of Science and Technology, Keio University, Yokohama, Japan.
PLoS One. 2013 Aug 29;8(8):e72741. doi: 10.1371/journal.pone.0072741. eCollection 2013.
The proper association between planned and executed movements is crucial for motor learning because the discrepancies between them drive such learning. Our study explored how this association was determined when a single action caused the movements of multiple visual objects. Participants reached toward a target by moving a cursor, which represented the right hand's position. Once every five to six normal trials, we interleaved either of two kinds of visual perturbation trials: rotation of the cursor by a certain amount (±15°, ±30°, and ±45°) around the starting position (single-cursor condition) or rotation of two cursors by different angles (+15° and -45°, 0° and 30°, etc.) that were presented simultaneously (double-cursor condition). We evaluated the aftereffects of each condition in the subsequent trial. The error sensitivity (ratio of the aftereffect to the imposed visual rotation) in the single-cursor trials decayed with the amount of rotation, indicating that the motor learning system relied to a greater extent on smaller errors. In the double-cursor trials, we obtained a coefficient that represented the degree to which each of the visual rotations contributed to the aftereffects based on the assumption that the observed aftereffects were a result of the weighted summation of the influences of the imposed visual rotations. The decaying pattern according to the amount of rotation was maintained in the coefficient of each imposed visual rotation in the double-cursor trials, but the value was reduced to approximately 40% of the corresponding error sensitivity in the single-cursor trials. We also found a further reduction of the coefficients when three distinct cursors were presented (e.g., -15°, 15°, and 30°). These results indicated that the motor learning system utilized multiple sources of visual error information simultaneously to correct subsequent movement and that a certain averaging mechanism might be at work in the utilization process.
计划运动与执行运动之间的适当关联对于运动学习至关重要，因为它们之间的差异推动了这种学习。我们的研究探索了当一个单一动作导致多个视觉物体运动时，这种关联是如何确定的。参与者通过移动光标来朝向目标移动，光标代表右手的位置。在每五个到六个正常试验之间，我们会交错两种视觉干扰试验：光标围绕起始位置旋转一定角度（±15°、±30°和±45°）（单光标条件）或同时呈现两个角度不同的光标旋转（+15°和-45°、0°和 30°等）（双光标条件）。我们评估了后续试验中每种条件的后效。在单光标试验中，误差敏感性（后效与施加的视觉旋转之比）随旋转量的增加而降低，表明运动学习系统更依赖于较小的误差。在双光标试验中，我们根据观察到的后效是施加的视觉旋转影响的加权总和的假设，获得了一个表示每个视觉旋转对后效贡献程度的系数。在双光标试验中，根据旋转量的衰减模式保持了每个施加的视觉旋转的系数，但值降低到单光标试验中相应误差敏感性的约 40%。当呈现三个不同的光标时（例如，-15°、15°和 30°），我们还发现系数进一步降低。这些结果表明，运动学习系统同时利用多个视觉误差信息来纠正后续运动，并且在利用过程中可能存在某种平均机制。
