Abdulkarim Zakaryah, Ehrsson H Henrik
Department of Neuroscience, Karolinska Insitutet, Retzius väg 8, 171 77, Solna, Sweden.
Exp Brain Res. 2018 Feb;236(2):551-561. doi: 10.1007/s00221-017-5137-7. Epub 2017 Dec 14.
Precise knowledge of one's limbs' position in space is fundamental for goal-directed action. The brain's representation of the body in space is thought to be generated through a process of multisensory integration of visual, tactile and proprioceptive signals. In this study, we devised a setup that allowed us to displace participants' right hand without their subjective awareness. We accomplished this task by instructing the participants to view a live video feed of their hand from the first-person perspective. In the active condition, we used a sensorimotor illusion that caused the participants to actively but unknowingly displace their unseen right hand to a location 8 cm lateral to the image of their hand. In the passive condition, we mechanically displaced the participants' hand-at a slow, unnoticeable velocity-to the same location. We found that during active displacement, the participants indicated that the location of their hand was closer to the digital image of the hand rather than the veridical location of the hand, as compared with the passive condition, in which the participants indicated that the locations of their hand were closer to the actual location. These results indicated that, compared with passive displacement, active movements cause greater recalibration of the hand's spatial position and that the boosted spatial recalibration of hand position sense in the active task is driven by error-based sensorimotor corrections. These results have bearing on the perceptual mechanisms of recalibration of perceived limb location.
精确知晓自身肢体在空间中的位置是目标导向行动的基础。大脑对身体在空间中的表征被认为是通过视觉、触觉和本体感觉信号的多感官整合过程产生的。在本研究中，我们设计了一种装置，使我们能够在参与者没有主观意识的情况下移动其右手。我们通过指示参与者从第一人称视角观看其手部的实时视频来完成这项任务。在主动条件下，我们利用一种感觉运动错觉，使参与者在不知不觉中主动将其看不见的右手移动到其手部图像外侧8厘米处的位置。在被动条件下，我们以缓慢、不易察觉的速度将参与者的手机械地移动到相同位置。我们发现，与被动条件相比，在主动移动过程中，参与者表示其手部位置更接近手部的数字图像，而非手部的真实位置，在被动条件下参与者表示其手部位置更接近实际位置。这些结果表明，与被动移动相比，主动移动会导致手部空间位置的更大程度重新校准，并且主动任务中手部位置感增强的空间重新校准是由基于误差的感觉运动校正驱动的。这些结果与感知肢体位置重新校准的感知机制有关。
