University of Bologna, Cesena, Italy.
J Cogn Neurosci. 2011 Mar;23(3):503-13. doi: 10.1162/jocn.2010.21484. Epub 2010 Mar 29.
The perception of tactile stimuli on the face is modulated if subjects concurrently observe a face being touched; this effect, termed visual remapping of touch (VRT), is maximum for observing one's own face. In the present fMRI study, we investigated the neural basis of the VRT effect. Participants in the scanner received tactile stimuli, near the perceptual threshold, on their right, left, or both cheeks. Concurrently, they watched movies depicting their own face, another person's face, or a ball that could be touched or only approached by human fingers. Participants were requested to distinguish between unilateral and bilateral tactile stimulation. Behaviorally, perception of tactile stimuli was modulated by viewing a tactile stimulation, with a stronger effect when viewing one's own face being touched. In terms of brain activity, viewing touch was related with an enhanced activity in the ventral intraparietal area. The specific effect of viewing touch on oneself was instead related with a reduced activity in both the ventral premotor cortex and the somatosensory cortex. The present findings suggest that VRT is supported by a network of fronto-parietal areas. The ventral intraparietal area might remap visual information about touch onto tactile processing. Ventral premotor cortex might specifically modulate multisensory interaction when sensory information is related to one's own body. Then this activity might back project to the somatosensory cortices, thus affecting tactile perception.
当受试者同时观察到面部被触碰时，面部触觉刺激的感知会发生变化；这种效应被称为视觉触觉映射（VRT），当观察到自己的脸时，效果最大。在本 fMRI 研究中，我们研究了 VRT 效应的神经基础。扫描器内的参与者在右脸颊、左脸颊或两侧脸颊接受接近感知阈值的触觉刺激。同时，他们观看了描述自己的脸、别人的脸或一个可以用手指触摸或接近的球的电影。参与者被要求区分单侧和双侧触觉刺激。行为上，触觉刺激的感知受到观看触觉刺激的调节，当观看自己的脸被触碰时，效果更强。就大脑活动而言，观看触摸与腹侧顶内区的活动增强有关。而观看自己的触摸的特定效果则与腹侧运动前皮质和躯体感觉皮质的活动减少有关。本研究结果表明，VRT 得到了额顶叶区域网络的支持。腹侧顶内区可能将有关触摸的视觉信息重新映射到触觉处理上。腹侧运动前皮质可能在感觉信息与自身身体相关时特异性地调节多感觉相互作用。然后，这种活动可能会向后投射到躯体感觉皮质，从而影响触觉感知。
