Ricci Raffaella, Caldano Michela, Sabatelli Ilaria, Cirillo Emanuele, Gammeri Roberto, Cesim Ezgi, Salatino Adriana, Berti Anna
Department of Psychology, University of Turin, Turin, Italy.
Department of Neuroscience, Dokuz Eylul University, Alsancak, Turkey.
Front Hum Neurosci. 2021 Dec 1;15:734235. doi: 10.3389/fnhum.2021.734235. eCollection 2021.
In the present article, we investigated the possibility of inducing phantom tactile sensations in healthy individuals similar to those that we observed in patients after stroke. On the basis of previous research, we assumed that manipulating visual feedbacks may guide and influence, under certain conditions, the phenomenal experience of touch. To this aim, we used the Tactile Quadrant Stimulation (TQS) test in which subjects, in the crucial condition, must indicate whether and where they perceive a double tactile stimulation applied simultaneously in different quadrants of the two hands (asymmetrical Double Simultaneous Stimulation trial, Asym-DSS). The task was performed with the left-hand out of sight and the right-hand reflected in a mirror so that the right-hand reflected in the mirror looks like the own left-hand. We found that in the Asym-DSS trial, the vision of the right-hand reflected in the mirror and stimulated by a tactile stimulus elicited on the left-hand the sensation of having been touched in the same quadrant as the right-hand. In other words, we found in healthy subjects the same phantom touch effect that we previously found in patients. We interpreted these results as modulation of tactile representation by bottom-up (multisensory integration of stimuli coming from the right real and the right reflected hand) and possibly top-down (body ownership distortion) processing triggered by our experimental setup, unveiling bilateral representation of touch.
在本文中，我们研究了在健康个体中诱发幻触感觉的可能性，这种感觉类似于我们在中风患者身上观察到的感觉。基于先前的研究，我们假设在某些条件下，操纵视觉反馈可能会引导和影响触觉的现象学体验。为此，我们使用了触觉象限刺激（TQS）测试，在关键条件下，受试者必须指出他们是否以及在何处感知到在两只手的不同象限同时施加的双重触觉刺激（不对称双同时刺激试验，Asym-DSS）。该任务是在左手看不见且右手在镜子中反射的情况下进行的，这样镜子中反射的右手看起来就像自己的左手。我们发现，在Asym-DSS试验中，镜子中反射的右手并受到左手施加的触觉刺激所引发的视觉，会引起在与右手相同象限被触摸的感觉。换句话说，我们在健康受试者中发现了与之前在患者中发现的相同的幻触效应。我们将这些结果解释为由我们的实验设置触发的自下而上（来自真实右手和反射右手的刺激的多感官整合）以及可能的自上而下（身体所有权扭曲）处理对触觉表征的调制，揭示了触觉的双侧表征。
