Dionne Jennifer K, Henriques Denise Y P
School of Kinesiology and Health Science, York University, Toronto, ON, Canada.
J Vis. 2008 Nov 10;8(15):2.1-10. doi: 10.1167/8.15.2.
Previous studies have shown that learning to reach accurately with an imposed visuomotor rotation requires a remapping of the relationship between vision and motor output. In this preliminary study, we examine how the brain works out the appropriate motor adjustments, in this case for both arms, based on visual images. Specifically, we investigate how visual errors seen while adapting reaches to visual targets affect the movements of both the trained and untrained hand. In our task subjects learned to make accurate reaches to targets in four visual feedback conditions: rotated 45 degrees, rotated 105 degrees, reversed left to right and rotated 45 degrees plus reversed. In all conditions the rotation was applied to the subject's feedback of their hand and not the targets. In the reversed and rotated-reversed condition, when the subject used their right hand, the feedback looked like their left hand (and vice versa). After a training period with one hand (e.g., right) subjects were tested with the opposite hand (e.g., left) on the same task. We predicted that after reaching with the right hand with reversed visual feedback the control of the left arm would also be altered-more so than after learning an equal-sized adjustment to right-arm reaching with a rotated, but non-reversed, view of their hand movements. Our results showed that people were able to learn the visuomotor adaptation with reversed visual feedback, but more interestingly, that learning occurred for the untrained hand as well for the reversed conditions alone. Here, vision alone--when it resembles the image of the opposite hand--led to improved initial performance for this opposite, untrained arm when reaching in a similar task. The brain seems to take advantage of reversed visual feedback of the arm to adjust the motor commands to the untrained arm in a way that facilitates transfer of the adaptation from one arm to the other.
先前的研究表明，学习在施加视觉运动旋转的情况下准确够取需要重新映射视觉与运动输出之间的关系。在这项初步研究中，我们研究大脑如何根据视觉图像做出适当的运动调整，在这种情况下是针对双臂。具体而言，我们研究在使够取动作适应视觉目标时看到的视觉误差如何影响训练手和未训练手的运动。在我们的任务中，受试者学习在四种视觉反馈条件下准确够取目标：旋转45度、旋转105度、左右反转以及旋转45度加反转。在所有条件下，旋转都应用于受试者手部的反馈而非目标。在反转和旋转反转条件下，当受试者使用右手时，反馈看起来像他们的左手（反之亦然）。在用一只手（例如右手）进行训练期后，受试者在相同任务上用另一只手（例如左手）进行测试。我们预测，在用右手进行带有反转视觉反馈的够取动作后，左臂的控制也会改变——比在学习对右手够取动作进行同等大小的调整（但手部运动视图为旋转而非反转）后改变得更多。我们的结果表明，人们能够通过反转视觉反馈学习视觉运动适应，但更有趣的是，仅在反转条件下，未训练的手也会发生学习。在这里，仅视觉——当它类似于另一只手的图像时——在进行类似任务的够取动作时会导致这只相反的、未训练的手臂的初始表现得到改善。大脑似乎利用手臂的反转视觉反馈以一种促进适应从一只手臂转移到另一只手臂的方式调整对未训练手臂的运动指令。
