Itaguchi Yoshihiro, Fukuzawa Kazuyoshi
Department of System Design Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku, Yokohama, Kanagawa, 223-8522, Japan.
Japan Society for the Promotion of Science, Kojimachi Business Center Building, 5-3-1 Kojimachi, Chiyoda, Tokyo, 102-0083, Japan.
Exp Brain Res. 2019 Jan;237(1):147-159. doi: 10.1007/s00221-018-5409-x. Epub 2018 Oct 25.
The present study tested whether remapping of visuomotor correspondence alters automatic motor responses induced by visual stimuli. We hypothesized that the congruency effect, an automatic modulation of motor responses based on stimulus-response congruency, changes in accordance with a new visuomotor correspondence acquired through an adaptation task. To induce visuomotor adaptation, participants performed a tracking task with 30° or 150° rotation of the visual feedback. The congruency effect was evaluated multiple times by a visual response task where participants moved their finger left or right. We predicted that the congruency effect, as a measure of automatic responses, would be almost reversed after adaptation to the 150° rotation, because a visual stimulus spatially opposite to the participant's own action would become a "congruent" stimulus in a 150°-rotated environment but not in a 30°-rotation environment. The results show that visuomotor adaptation to the 150° rotation did modulate the congruency effect in accordance with the acquired visuomotor correspondence, but did not completely reverse the effect. When the effect was assessed after the manipulation, which was assumed to switch an internal model back to its normal state, there was no change in automatic motor responses. Furthermore, we found that after effects developed as the training proceeded but decreased over time. These findings suggest that the visuomotor system subserving automatic modulation in motor responses is based on the currently active internal model and, therefore, highly adaptive. In addition, the mechanism underlying after effects in a visuomotor task is discussed in terms of a switching function of internal models.
本研究测试了视觉运动对应关系的重新映射是否会改变由视觉刺激诱发的自动运动反应。我们假设一致性效应，即基于刺激-反应一致性的运动反应的自动调节，会根据通过适应任务获得的新视觉运动对应关系而发生变化。为了诱发视觉运动适应，参与者执行了一项视觉反馈旋转30°或150°的跟踪任务。通过一项视觉反应任务对一致性效应进行了多次评估，在该任务中参与者将手指向左或向右移动。我们预测，作为自动反应度量的一致性效应，在适应150°旋转后几乎会反转，因为在150°旋转的环境中，与参与者自身动作在空间上相反的视觉刺激将成为“一致”刺激，而在30°旋转环境中则不然。结果表明，对150°旋转的视觉运动适应确实根据获得的视觉运动对应关系调节了一致性效应，但并未完全反转该效应。当在假定将内部模型切换回其正常状态的操作之后评估该效应时，自动运动反应没有变化。此外，我们发现后效随着训练的进行而发展，但会随着时间而减弱。这些发现表明，服务于运动反应自动调节的视觉运动系统基于当前活跃的内部模型，因此具有高度适应性。此外，还从内部模型的切换功能角度讨论了视觉运动任务中后效的潜在机制。
