Department of Biomedical Engineering, Ben-Gurion University of the Negev, Be'er Sheva, Israel.
Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Be'er Sheva, Israel.
eNeuro. 2017 Dec 26;4(6). doi: 10.1523/ENEURO.0179-17.2017. eCollection 2017 Nov-Dec.
To accurately estimate the state of the body, the nervous system needs to account for delays between signals from different sensory modalities. To investigate how such delays may be represented in the sensorimotor system, we asked human participants to play a virtual pong game in which the movement of the virtual paddle was delayed with respect to their hand movement. We tested the representation of this new mapping between the hand and the delayed paddle by examining transfer of adaptation to blind reaching and blind tracking tasks. These blind tasks enabled to capture the representation in feedforward mechanisms of movement control. A Time Representation of the delay is an estimation of the actual time lag between hand and paddle movements. A State Representation is a representation of delay using current state variables: the distance between the paddle and the ball originating from the delay may be considered as a spatial shift; the low sensitivity in the response of the paddle may be interpreted as a minifying gain; and the lag may be attributed to a mechanical resistance that influences paddle's movement. We found that the effects of prolonged exposure to the delayed feedback transferred to blind reaching and tracking tasks and caused participants to exhibit hypermetric movements. These results, together with simulations of our representation models, suggest that delay is not represented based on time, but rather as a spatial gain change in visuomotor mapping.
为了准确估计身体状态，神经系统需要考虑来自不同感觉模态的信号之间的延迟。为了研究这种延迟可能如何在感觉运动系统中表示，我们要求人类参与者玩一个虚拟乒乓球游戏，其中虚拟球拍的运动相对于他们的手的运动延迟。我们通过检查适应的转移来测试手和延迟球拍之间的这种新映射的表示，适应的转移分别在盲目伸手和盲目跟踪任务中进行。这些盲目任务使运动控制的前馈机制中的表示能够被捕获。延迟的时间表示是对手和球拍运动之间实际时滞的估计。状态表示是使用当前状态变量表示延迟的一种方式：延迟产生的球拍和球之间的距离可以被认为是空间的转移；球拍响应的低灵敏度可以被解释为缩小的增益；而延迟可以归因于影响球拍运动的机械阻力。我们发现，长时间暴露于延迟反馈的影响转移到盲目伸手和跟踪任务中，导致参与者表现出超距运动。这些结果，以及我们的表示模型的模拟，表明延迟不是基于时间表示的，而是作为视觉运动映射中的空间增益变化来表示的。
