Guterstam Arvid, Zeberg Hugo, Özçiftci Vedat Menderes, Ehrsson H Henrik
Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 171 77 Stockholm, Sweden.
Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 171 77 Stockholm, Sweden.
Cognition. 2016 Oct;155:44-56. doi: 10.1016/j.cognition.2016.06.004. Epub 2016 Jun 24.
To accurately localize our limbs and guide movements toward external objects, the brain must represent the body and its surrounding (peripersonal) visual space. Specific multisensory neurons encode peripersonal space in the monkey brain, and neurobehavioral studies have suggested the existence of a similar representation in humans. However, because peripersonal space lacks a distinct perceptual correlate, its involvement in spatial and bodily perception remains unclear. Here, we show that applying brushstrokes in mid-air at some distance above a rubber hand-without touching it-in synchrony with brushstrokes applied to a participant's hidden real hand results in the illusory sensation of a "magnetic force" between the brush and the rubber hand, which strongly correlates with the perception of the rubber hand as one's own. In eight experiments, we characterized this "magnetic touch illusion" by using quantitative subjective reports, motion tracking, and behavioral data consisting of pointing errors toward the rubber hand in an intermanual pointing task. We found that the illusion depends on visuo-tactile synchrony and exhibits similarities with the visuo-tactile receptive field properties of peripersonal space neurons, featuring a non-linear decay at 40cm that is independent of gaze direction and follows changes in the rubber hand position. Moreover, the "magnetic force" does not penetrate physical barriers, thus further linking this phenomenon to body-specific visuo-tactile integration processes. These findings provide strong support for the notion that multisensory integration within peripersonal space underlies bodily self-attribution. Furthermore, we propose that the magnetic touch illusion constitutes a perceptual correlate of visuo-tactile integration in peripersonal space.
为了准确地定位我们的肢体并引导动作指向外部物体，大脑必须表征身体及其周围（个人周边）的视觉空间。特定的多感觉神经元在猴脑中编码个人周边空间，神经行为学研究表明人类中也存在类似的表征。然而，由于个人周边空间缺乏明显的感知关联，其在空间和身体感知中的作用仍不清楚。在这里，我们表明，在橡胶手上方一定距离的空中进行笔触操作——不接触橡胶手——同时对参与者隐藏的真实手部进行笔触操作，会导致在刷子和橡胶手之间产生“磁力”的错觉，这种错觉与将橡胶手视为自己的手的感知密切相关。在八项实验中，我们通过定量主观报告、运动跟踪以及在双手指向任务中指向橡胶手的指向误差组成的行为数据，对这种“磁触错觉”进行了表征。我们发现，这种错觉取决于视觉触觉同步，并与个人周边空间神经元的视觉触觉感受野特性相似，在40厘米处呈现非线性衰减，且与注视方向无关，并随橡胶手位置的变化而变化。此外，“磁力”不会穿透物理屏障，从而进一步将这一现象与特定身体的视觉触觉整合过程联系起来。这些发现为个人周边空间内的多感觉整合是身体自我归属的基础这一观点提供了有力支持。此外，我们提出磁触错觉构成了个人周边空间中视觉触觉整合的一种感知关联。
