Medina Jared, DePasquale Carrie
Department of Psychological and Brain Sciences, University of Delaware, USA.
Institute of Child Development, University of Minnesota, USA.
Cortex. 2017 Mar;88:53-65. doi: 10.1016/j.cortex.2016.12.013. Epub 2016 Dec 24.
Individuals with mirror-touch synesthesia (MTS) report feeling touch on their own body when seeing someone else being touched. We examined how the body schema - an on-line representation of body position in space - is involved in mapping touch from a viewed body to one's own body. We showed 45 mirror-touch synesthetes videos of a hand being touched, varying the location of the viewed touch by hand (left, right), skin surface (palmar, dorsal) and finger (index, ring). Participant hand posture was either congruent or incongruent with the posture of the viewed hand. After seeing the video, participants were asked to report whether they felt touch on their own body and, if so, the intensity and location of their percepts. We found that participants reported more frequent and more veridical (i.e., felt at the same somatotopic location as the viewed touch) mirror-touch percepts on posturally congruent versus posturally incongruent trials. Furthermore, participant response patterns varied as a function of postural congruence. Some participants consistently felt sensations on the hand surface that was stimulated in the video - even if their hands were in the opposite posture. Other participants' responses were modulated based on their own hand position, such that percepts were more likely to be felt on the upright, plausible hand surface in the posturally incongruent condition. These results provide evidence that mapping viewed touch to one's own body involves an on-line representation of body position in space.
患有镜像触觉联觉（MTS）的人在看到别人被触摸时，会报告自己身体上也有被触摸的感觉。我们研究了身体图式——空间中身体位置的一种在线表征——是如何参与将看到的身体上的触摸映射到自己身体上的过程的。我们向45名镜像触觉联觉者展示了一只手被触摸的视频，通过手（左手、右手）、皮肤表面（手掌、手背）和手指（食指、无名指）来改变看到的触摸位置。参与者的手部姿势与看到的手部姿势要么一致，要么不一致。看完视频后，参与者被要求报告他们是否在自己身体上感觉到了触摸，如果感觉到了，要报告其感觉的强度和位置。我们发现，与姿势不一致的试验相比，参与者在姿势一致的试验中报告的镜像触觉感知更频繁、更真实（即，感觉在与看到的触摸相同的躯体感觉位置）。此外，参与者的反应模式因姿势一致性而有所不同。一些参与者始终在视频中被刺激的手部表面感觉到了感觉——即使他们的手处于相反的姿势。其他参与者的反应则根据他们自己的手部位置进行调节，以至于在姿势不一致的情况下，感知更有可能出现在直立、合理的手部表面。这些结果提供了证据，表明将看到的触摸映射到自己身体上涉及空间中身体位置的在线表征。
