Lefrançois Catherine, Messier Julie
École de kinésiologie et des sciences de l'activité physique, Faculté de médecine, Université de Montréal, 2100, boul. Édouard-Montpetit, bureau 8225, Montreal, QC, H3T 1J4, Canada.
Institut universitaire de gériatrie de Montréal, Université de Montréal, Montréal, QC, Canada.
Exp Brain Res. 2019 Mar;237(3):793-803. doi: 10.1007/s00221-018-05462-2. Epub 2019 Jan 3.
We explored visuomotor adaptation and spatial generalization of three-dimensional reaching movements performed in a virtual reality environment. We used a multiphase learning paradigm. First, subjects performed reaching movements to six targets without visual feedback (VF) (pre-exposure phase). Next, participants aimed at one target with veridical VF (baseline phase). Immediately after, they were required to adapt their movements to a triaxial visuomotor perturbation (horizontal, vertical, and sagittal translations) between actual hand motion and VF of hand motion in the virtual environment (learning phase). Finally, subjects aimed at the same targets as in the baseline (aftereffect) and pre-exposure phases (generalization) without VF (post-exposure phase). The results revealed spatial axis-dependent visuomotor adaptation capacities. First, subjects showed smaller intertrial variability along the horizontal compared to the sagittal and vertical axes during the baseline and learning phases. Second, although subjects were unaware of the visual distortion, they adapted their movements to each component of the triaxial perturbation. However, they showed reduced learning rate and less persistent adaptation (aftereffect) along the vertical than the horizontal and sagittal axes. Similarly, subjects transferred the newly learned visuomotor association to untrained regions of the workspace, but their average level of generalization was smaller along the vertical than the horizontal and sagittal axes. Collectively, our results suggest that adapting three-dimensional movements to a visual distortion involves distinct processes according to the specific sensorimotor integration demands of moving along each spatial axis. This finding supports the idea that the brain employs a modular decomposition strategy to simplify complex multidimensional visuomotor tasks.
我们探究了在虚拟现实环境中进行的三维伸手动作的视觉运动适应和空间泛化。我们采用了多阶段学习范式。首先，受试者在没有视觉反馈（VF）的情况下对六个目标进行伸手动作（预暴露阶段）。接下来，参与者在真实的视觉反馈下瞄准一个目标（基线阶段）。之后，他们被要求在虚拟环境中，将自己的动作适应于实际手部动作和手部动作的视觉反馈之间的三轴视觉运动扰动（水平、垂直和矢状平移）（学习阶段）。最后，受试者在没有视觉反馈的情况下，瞄准与基线（后效应）和预暴露阶段相同的目标（泛化）（暴露后阶段）。结果揭示了空间轴依赖性视觉运动适应能力。首先，在基线和学习阶段，与矢状轴和垂直轴相比，受试者在水平轴上的试验间变异性更小。其次，尽管受试者没有意识到视觉扭曲，但他们将自己的动作适应于三轴扰动的每个组成部分。然而，与水平轴和矢状轴相比，他们在垂直轴上的学习率降低，适应的持续性也更小（后效应）。同样，受试者将新学到的视觉运动关联转移到了工作空间的未训练区域，但他们在垂直轴上的平均泛化水平低于水平轴和矢状轴。总体而言，我们的结果表明，根据沿每个空间轴移动的特定感觉运动整合需求，将三维动作适应于视觉扭曲涉及不同的过程。这一发现支持了大脑采用模块化分解策略来简化复杂的多维视觉运动任务的观点。
