Department of Philosophy and Communication, University of Bologna, Via Azzo Gardino 23, 40122, Bologna, Italy.
Human Cognitive Neuroscience, University of Edinburgh, Edinburgh, UK.
Exp Brain Res. 2022 Aug;240(7-8):2039-2050. doi: 10.1007/s00221-022-06387-7. Epub 2022 Jun 21.
Peripersonal space (PPS), the space closely surrounding the body, is typically characterised by enhanced multisensory integration. Neurophysiological and behavioural studies have consistently shown stronger visuo-tactile integration when a visual stimulus is presented close to the tactually stimulate body part in near space (within PPS) than in far space. However, in the majority of these studies, tactile stimuli were delivered to the upper limbs, torso and face. Therefore, it is not known whether the space surrounding the lower limbs is characterised by similar multisensory properties. To address this question, we asked participants to complete two versions of the classic visuo-tactile crossmodal congruency task in which they had to perform speeded elevation judgements of tactile stimuli presented to the dorsum of the hand and foot while a simultaneous visual distractor was presented at spatially congruent or incongruent locations either in near or far space. In line with existing evidence, when the tactile target was presented to the hand, the size of the crossmodal congruency effect (CCE) decreased in far as compared to near space, suggesting stronger visuo-tactile multisensory integration within PPS. In contrast, when the tactile target was presented to the foot, the CCE decreased for visual distractors in near than far space. These findings show systematic differences between the representation of PPS around upper and lower limbs, suggesting that the multisensory properties of the different body part-centred representations of PPS are likely to depend on the potential actions performed by the different body parts.
个体空间（PPS）是指身体周围的空间，其特点是增强了多感觉整合。神经生理学和行为学研究一致表明，当视觉刺激接近近空间（PPS 内）的触觉刺激身体部位时，视觉-触觉整合更强，而当视觉刺激处于远空间时则较弱。然而，在大多数这些研究中，触觉刺激被传递到上肢、躯干和面部。因此，尚不清楚下肢周围的空间是否具有类似的多感觉特性。为了解决这个问题，我们要求参与者完成两种经典的视听跨模态一致性任务版本，在这些任务中，他们必须对手掌和脚背部的触觉刺激进行快速提升判断，同时在近空间或远空间中，同时呈现视觉干扰刺激，位置在空间上一致或不一致。与现有证据一致，当触觉目标被呈现到手部时，与近空间相比，远空间的跨模态一致性效应（CCE）减小，表明 PPS 内的视觉-触觉多感觉整合更强。相比之下，当触觉目标呈现到脚部时，近空间的视觉干扰物的 CCE 比远空间的减小。这些发现显示了上肢和下肢周围 PPS 表示之间的系统差异，表明 PPS 的不同以身体部位为中心的表示的多感觉特性可能取决于不同身体部位执行的潜在动作。
