Cléry Justine, Guipponi Olivier, Odouard Soline, Wardak Claire, Ben Hamed Suliann
Centre de Neuroscience Cognitive, CNRS UMR 5229, Université Claude Bernard Lyon I, 69675 Bron cedex, France.
Centre de Neuroscience Cognitive, CNRS UMR 5229, Université Claude Bernard Lyon I, 69675 Bron cedex, France
J Neurosci. 2015 Mar 11;35(10):4179-89. doi: 10.1523/JNEUROSCI.3031-14.2015.
From an ecological point of view, approaching objects are potentially more harmful than receding objects. A predator, a dominant conspecific, or a mere branch coming up at high speed can all be dangerous if one does not detect them and produce the appropriate escape behavior fast enough. And indeed, looming stimuli trigger stereotyped defensive responses in both monkeys and human infants. However, while the heteromodal somatosensory consequences of visual looming stimuli can be fully predicted by their spatiotemporal dynamics, few studies if any have explored whether visual stimuli looming toward the face predictively enhance heteromodal tactile sensitivity around the expected time of impact and at its expected location on the body. In the present study, we report that, in addition to triggering a defensive motor repertoire, looming stimuli toward the face provide the nervous system with predictive cues that enhance tactile sensitivity on the face. Specifically, we describe an enhancement of tactile processes at the expected time and location of impact of the stimulus on the face. We additionally show that a looming stimulus that brushes past the face also enhances tactile sensitivity on the nearby cheek, suggesting that the space close to the face is incorporated into the subjects' body schema. We propose that this cross-modal predictive facilitation involves multisensory convergence areas subserving the representation of a peripersonal space and a safety boundary of self.
从生态学角度来看，接近的物体可能比远离的物体更具危险性。如果个体不能及时察觉并迅速做出适当的逃避行为，那么捕食者、占主导地位的同种个体，或者仅仅是高速靠近的一根树枝，都可能构成危险。事实上，逼近的刺激会在猴子和人类婴儿身上引发刻板的防御反应。然而，虽然视觉逼近刺激的异模态躯体感觉后果可以通过其时空动态完全预测，但几乎没有研究（如果有的话）探讨过朝着面部逼近的视觉刺激是否会在预期的撞击时间及其在身体上的预期位置，预测性地增强异模态触觉敏感性。在本研究中，我们报告称，除了引发一系列防御性动作外，朝着面部逼近的刺激还为神经系统提供了预测线索，从而增强面部的触觉敏感性。具体而言，我们描述了在刺激预期撞击面部的时间和位置，触觉过程得到增强。我们还表明，擦过面部的逼近刺激也会增强附近脸颊的触觉敏感性，这表明靠近面部的空间被纳入了受试者的身体图式。我们提出，这种跨模态预测促进涉及多感觉汇聚区域，这些区域服务于个人周边空间的表征和自我的安全边界。
