Université Grenoble-Alpes, Université Savoie Mont Blanc, CNRS, UMR5105, LPNC, Grenoble, France.
Defitech Chair of Clinical Neuroengineering, Center for Neuroprosthetics (CNP) and Brain Mind Institute (BMI), Swiss Federal Institute of Technology Lausanne (EPFL), Campus Biotech, Geneva, Switzerland.
J Cogn Neurosci. 2024 Jan 1;36(1):143-154. doi: 10.1162/jocn_a_02074.
The growing popularity of virtual reality systems has led to a renewed interest in understanding the neurophysiological correlates of the illusion of self-motion (vection), a phenomenon that can be both intentionally induced or avoided in such systems, depending on the application. Recent research has highlighted the modulation of α power oscillations over the superior parietal cortex during vection, suggesting the occurrence of inhibitory mechanisms in the sensorimotor and vestibular functional networks to resolve the inherent visuo-vestibular conflict. The present study aims to further explore this relationship and investigate whether neuromodulating these waves could causally affect the quality of vection. In a crossover design, 22 healthy volunteers received high amplitude and focused α-tACS (transcranial alternating current stimulation) over the superior parietal cortex while experiencing visually induced vection triggered by optokinetic stimulation. The tACS was tuned to each participant's individual α peak frequency, with θ-tACS and sham stimulation serving as controls. Overall, participants experienced better quality vection during α-tACS compared with control θ-tACS and sham stimulations, as quantified by the intensity of vection. The observed neuromodulation supports a causal relationship between parietal α oscillations and visually induced self-motion illusions, with their entrainment triggering overinhibition of the conflict within the sensorimotor and vestibular functional networks. These results confirm the potential of noninvasive brain stimulation for modulating visuo-vestibular conflicts, which could help to enhance the sense of presence in virtual reality environments.
虚拟现实系统的日益普及，促使人们重新关注对运动错觉（即视动错觉）的神经生理学相关性的理解。视动错觉是一种现象，可以在这些系统中根据应用有意诱导或避免。最近的研究强调了在视动错觉期间，顶叶上皮质的α 功率振荡的调制，这表明在感觉运动和前庭功能网络中存在抑制机制，以解决固有的视-前庭冲突。本研究旨在进一步探讨这种关系，并研究神经调节这些波是否可以因果地影响视动错觉的质量。在一项交叉设计中，22 名健康志愿者在经历由视动刺激触发的视觉诱导的视动错觉时，接受了高强度和聚焦的 α-tACS（经颅交流电刺激）在顶叶上皮质。tACS 根据每个参与者的个体α 峰频率进行调整，θ-tACS 和假刺激作为对照。总的来说，与对照的θ-tACS 和假刺激相比，参与者在α-tACS 期间体验到了更好的视动错觉质量，这可以通过视动错觉的强度来量化。观察到的神经调节支持顶叶α 振荡与视觉诱导的自我运动错觉之间的因果关系，其引发的同步作用触发了感觉运动和前庭功能网络内冲突的过度抑制。这些结果证实了非侵入性脑刺激在调节视-前庭冲突方面的潜力，这有助于增强虚拟现实环境中的存在感。
