Aix Marseille Univ, CNRS, ISM, Marseille, France.
Univ. Lille, CNRS, UMR 9193 - SCALab - Sciences Cognitives et Sciences Affectives, 59000, Lille, France.
Exp Brain Res. 2021 Jan;239(1):31-46. doi: 10.1007/s00221-020-05945-1. Epub 2020 Oct 23.
Most of our daily interactions with objects occur in the space immediately surrounding the body, i.e. the peripersonal space. The peripersonal space is characterized by multisensory processing of objects which are coded in terms of potential actions, specifying for instance whether objects are within reach or not. Our recent work suggested a link between exposure to a new force field, which changed the effector dynamics, and the representation of peripersonal space. To better understand the interplay between the plasticity of the motor system and peripersonal space representation, the present study examined whether changing the direction of the force field specifically modified the perception of action boundaries. Participants seated at the centre of an experimental platform estimated visual targets' reachability before and after adapting upper-limb reaching movements to the Coriolis force generated by either clockwise or counter clockwise rotation of the platform (120°/s). Opposite spatial after-effects were observed, showing that force-field adaptation depends on the direction of the rotation. In contrast, perceived action boundaries shifted leftward following exposure to the new force field, regardless of the direction of the rotation. Overall, these findings support the idea that abrupt exposure to a new force field results in a direction-specific updating of the central sensorimotor representations underlying the control of arm movements. Abrupt exposure to a new force field also results in a nonspecific shift in the perception of action boundaries, which is consistent with a contraction of the peripersonal space. Such effect, which does not appear to be related to state anxiety, could be related to the protective role of the peripersonal space in response to the uncertainty of the sensorimotor system induced by the abrupt modification of the environment.
我们与物体的大多数日常互动都发生在身体周围的空间中，即近体空间。近体空间的特点是对物体进行多感觉处理，这些处理是根据潜在动作进行编码的，例如指定物体是否在可触及的范围内。我们最近的工作表明，新力场的暴露与近体空间的表示之间存在联系，该力场改变了效应器的动态。为了更好地理解运动系统的可塑性和近体空间表示之间的相互作用，本研究探讨了改变力场的方向是否会特异性地改变对动作边界的感知。参与者坐在实验平台的中心，在适应上肢向心运动以适应平台顺时针或逆时针（120°/s）旋转产生的科里奥利力之前和之后，估计视觉目标的可及性。观察到相反的空间后效，表明力场适应取决于旋转的方向。相比之下，无论力场的方向如何，暴露于新力场后，感知到的动作边界都向左移动。总的来说，这些发现支持了这样一种观点，即突然暴露于新的力场会导致对控制手臂运动的中央感觉运动表示进行特定于方向的更新。突然暴露于新的力场也会导致动作边界的非特异性感知发生变化，这与近体空间的收缩一致。这种效应似乎与状态焦虑无关，可能与近体空间在响应环境突然改变引起的感觉运动系统不确定性时的保护作用有关。
