MySpace Lab, Department of Clinical Neurosciences, Lausanne University Hospital (CHUV), Lausanne, Switzerland.
MindMaze SA, Chemin de Roseneck 5, Lausanne, 1006, Switzerland.
Neuropsychologia. 2021 Jan 8;150:107692. doi: 10.1016/j.neuropsychologia.2020.107692. Epub 2020 Nov 21.
Prism adaptation is a method for studying visuomotor plasticity in healthy individuals, as well as for rehabilitating patients suffering spatial neglect. We developed a new set-up based on virtual-reality (VR) and haptic-robotics allowing us to induce sensorimotor adaptation and to reproduce the effect of prism adaptation in a more ecologically valid, yet experimentally controlled context. Participants were exposed to an immersive VR environment while controlling a virtual hand via a robotic-haptic device to reach virtual objects. During training, a rotational shift was induced between the position of the participant's real hand and that of the virtual hand in order to trigger sensorimotor recalibration. The use of VR and haptic-robotics allowed us to simulate and test multiple components of sensorimotor adaptation: training either peripersonal or extrapersonal space and testing generalization for the non-trained sector of space, and using active versus robot-guided reaching movements. Results from 60 neurologically intact participants show that participants exposed to the virtual shift were able to quickly adapt their reaching movements to aim correctly at the target objects. When the shift was removed, participants showed a systematic deviation of their movements during open-loop tasks in the direction opposite to that of the shift, which generalized to un-trained portions of space and occurred also when their movements were robotically-guided during the adaptation. Interestingly, follow-up questionnaires revealed that when the adaptation training was robotically-guided, participants were largely unaware of the mismatch between their hand and the virtual hand's position. The stability of the aftereffects, despite the changing experimental parameters, suggests that the induced sensory-motor adaptation does not rely on low-level processing of sensory stimuli during the training, but taps into high-level representations of space. Importantly, the flexibility of the trained space and the option of robotically-guided movements open novel possibilities of fine-tuning the training to patients' level of spatial and motor impairment, thus possibly resulting in a better outcome.
视动适应是一种研究健康个体视动可塑性的方法，也可用于康复空间忽略症患者。我们开发了一种新的基于虚拟现实（VR）和触觉机器人技术的设置，使我们能够在更具生态有效性但实验控制的环境中诱导感觉运动适应，并再现棱镜适应的效果。参与者在沉浸式 VR 环境中通过机器人触觉设备控制虚拟手来接触虚拟物体。在训练过程中，会在参与者的真实手和虚拟手的位置之间引入旋转偏移，以触发感觉运动重新校准。VR 和触觉机器人技术的使用使我们能够模拟和测试感觉运动适应的多个组件：训练个人空间或超个人空间，并测试非训练空间的泛化，以及使用主动或机器人引导的到达运动。来自 60 名神经完整参与者的结果表明，暴露于虚拟偏移的参与者能够快速适应他们的到达运动，以正确瞄准目标物体。当偏移移除时，参与者在开环任务中表现出系统的运动偏差，其方向与偏移的方向相反，这种偏差泛化到未训练的空间部分，并且在适应期间其运动由机器人引导时也会发生。有趣的是，后续问卷调查显示，当适应训练由机器人引导时，参与者在很大程度上没有意识到他们的手和虚拟手位置之间的不匹配。尽管实验参数不断变化，但后效的稳定性表明，诱导的感觉运动适应并不依赖于训练过程中对感觉刺激的低级处理，而是依赖于空间的高级表示。重要的是，训练空间的灵活性和机器人引导运动的选项为根据患者的空间和运动障碍程度对训练进行微调开辟了新的可能性，从而可能产生更好的结果。
