Tani Keisuke, Tanaka Hiroaki, Hirata Akimasa, Nagata Yosuke, Mori Nobuhiko, Hosomi Koichi, Matsugi Akiyoshi
Faculty of Psychology, Otemon Gakuin University, Ibaraki, Osaka 567-8502, Japan
Graduate School of Human and Environment Studies, Kyoto University, Kyoto, 606-8501, Japan.
eNeuro. 2025 Jul 30;12(7). doi: 10.1523/ENEURO.0111-25.2025. Print 2025 Jul.
Accurate perception of the direction of gravity relies on the integration of multisensory information, particularly from the visual and vestibular systems, within the brain. Although a recent study of patients with cerebellar degeneration suggested a cerebellar role in visuo-vestibular interaction in the perception of gravitational direction, direct evidence remains limited. To address this gap, we conducted two experiments with 42 healthy participants to evaluate the impact of repetitive 1 Hz transcranial magnetic stimulation (rTMS) over the posterior cerebellar vermis on visual dependency, quantified by the subjective visual vertical bias induced by rotating optokinetic stimulation (OKS). Electric field simulations in high-resolution generic head models were used to ensure focal stimulation of the cerebellum at the group level. The results demonstrated that the rTMS applied to the vermis significantly attenuated the OKS-induced shift in visual vertical (SVV) bias. This effect was not observed when stimulation was applied to the early visual cortex (V1-2) or the cerebellar hemisphere. Also, the vermis rTMS had no effect on the judgment precision in the absence of visual motion cues, suggesting that the rTMS may reduce visual weight in visuo-vestibular processing by increasing visual motion noise rather than affecting vestibular function. These findings suggest a direct involvement of the cerebellar vermis in the visuo-vestibular interaction underlying the perception of gravitational direction, providing new insights into cerebellar contributions in human spatial orientation.
对重力方向的准确感知依赖于大脑内多感官信息的整合，尤其是来自视觉和前庭系统的信息。尽管最近一项针对小脑变性患者的研究表明小脑在重力方向感知的视-前庭相互作用中发挥作用，但直接证据仍然有限。为了填补这一空白，我们对42名健康参与者进行了两项实验，以评估重复1赫兹经颅磁刺激（rTMS）作用于小脑蚓部后部对视觉依赖性的影响，视觉依赖性通过旋转视动刺激（OKS）诱发的主观视觉垂直偏差来量化。利用高分辨率通用头部模型进行电场模拟，以确保在群体水平上对小脑进行局部刺激。结果表明，施加于蚓部的rTMS显著减弱了OKS诱发的视觉垂直（SVV）偏差偏移。当刺激施加于早期视觉皮层（V1-2）或小脑半球时，未观察到这种效应。此外，在没有视觉运动线索的情况下，蚓部rTMS对判断精度没有影响，这表明rTMS可能通过增加视觉运动噪声而不是影响前庭功能来降低视-前庭处理中的视觉权重。这些发现表明小脑蚓部直接参与了重力方向感知背后的视-前庭相互作用，为小脑在人类空间定向中的作用提供了新的见解。
