Sutter Chloé, Moinon Alix, Felicetti Livia, Massi Francesco, Blouin Jean, Mouchnino Laurence
Laboratoire de Neurosciences Cognitives, FR 3C, CNRS, Aix Marseille Université, Marseille, France.
Department of Mechanical and Aerospace Engineering, Sapienza University of Rome, Rome, Italy.
Front Neurol. 2023 Jun 19;14:1175667. doi: 10.3389/fneur.2023.1175667. eCollection 2023.
Self-generated movement shapes tactile perception, but few studies have investigated the brain mechanisms involved in the processing of the mechanical signals related to the static and transient skin deformations generated by forces and pressures exerted between the foot skin and the standing surface. We recently found that standing on a biomimetic surface (i.e., inspired by the characteristics of mechanoreceptors and skin dermatoglyphics), that magnified skin-surface interaction, increased the sensory flow to the somatosensory cortex and improved balance control compared to standing on control (e.g., smooth) surfaces. In this study, we tested whether the well-known sensory suppression that occurs during movements is alleviated when the tactile afferent signal becomes relevant with the use of a biomimetic surface. Eyes-closed participants = 25) self-stimulated their foot cutaneous receptors by shifting their body weight toward one of their legs while standing on either a biomimetic or a control (smooth) surface. In a control task, similar forces were exerted on the surfaces (i.e., similar skin-surface interaction) by passive translations of the surfaces. Sensory gating was assessed by measuring the amplitude of the somatosensory-evoked potential over the vertex (SEP, recorded by EEG). Significantly larger and shorter SEPs were found when participants stood on the biomimetic surface. This was observed whether the forces exerted on the surface were self-generated or passively generated. Contrary to our prediction, we found that the sensory attenuation related to the self-generated movement did not significantly differ between the biomimetic and control surfaces. However, we observed an increase in gamma activity (30-50 Hz) over centroparietal regions during the preparation phase of the weight shift only when participants stood on the biomimetic surface. This result might suggest that gamma-band oscillations play an important functional role in processing behaviorally relevant stimuli during the early stages of body weight transfer.
自主产生的运动塑造触觉感知，但很少有研究调查大脑处理与足部皮肤和站立表面之间施加的力和压力所产生的静态和短暂皮肤变形相关的机械信号的机制。我们最近发现，站在仿生表面上（即受机械感受器和皮肤纹理特征启发），这种表面放大了皮肤与表面的相互作用，与站在对照（如光滑）表面相比，增加了体感皮层的感觉信息流并改善了平衡控制。在本研究中，我们测试了在使用仿生表面使触觉传入信号变得相关时，运动过程中发生的众所周知的感觉抑制是否会减轻。闭眼参与者（n = 25）在站在仿生或对照（光滑）表面上时，通过将体重转移到一条腿上来自我刺激足部皮肤感受器。在对照任务中，通过表面的被动平移在表面上施加类似的力（即类似的皮肤与表面的相互作用）。通过测量头顶上体感诱发电位的幅度（SEP，通过脑电图记录）来评估感觉门控。当参与者站在仿生表面上时，发现SEP明显更大且更短。无论施加在表面上的力是自主产生的还是被动产生的，均观察到这一现象。与我们的预测相反，我们发现与自主产生的运动相关的感觉衰减在仿生表面和对照表面之间没有显著差异。然而，仅当参与者站在仿生表面上时，我们观察到在体重转移的准备阶段，中央顶叶区域的伽马活动（30 - 50 Hz）增加。这一结果可能表明，伽马波段振荡在体重转移早期处理行为相关刺激中起重要的功能作用。
