Department Neurophysics, Philipps-Universität Marburg, Karl-Von-Frisch-Straße 8a, 35043, Marburg, Germany.
Center for Mind, Brain and Behavior, Philipps-Universität Marburg and Justus-Liebig-Universität Giessen, Giessen, Germany.
Sci Rep. 2023 Jun 19;13(1):9913. doi: 10.1038/s41598-023-36797-8.
Self-motion induces sensory signals that allow to determine travel distance (path integration). For veridical path integration, one must distinguish self-generated from externally induced sensory signals. Predictive coding has been suggested to attenuate self-induced sensory responses, while task relevance can reverse the attenuating effect of prediction. But how is self-motion processing affected by prediction and task demands, and do effects generalize across senses? In this fMRI study, we investigated visual and tactile self-motion processing and its modulation by task demands. Visual stimuli simulated forward self-motion across a ground plane. Tactile self-motion stimuli were delivered by airflow across the subjects' forehead. In one task, subjects replicated a previously observed distance (Reproduction/Active; high behavioral demand) of passive self-displacement (Reproduction/Passive). In a second task, subjects travelled a self-chosen distance (Self/Active; low behavioral demand) which was recorded and played back to them (Self/Passive). For both tasks and sensory modalities, Active as compared to Passive trials showed enhancement in early visual areas and suppression in higher order areas of the inferior parietal lobule (IPL). Contrasting high and low demanding active trials yielded supramodal enhancement in the anterior insula. Suppression in the IPL suggests this area to be a comparator of sensory self-motion signals and predictions thereof.
自身运动引起的感觉信号可以用来确定行进距离（路径整合）。为了实现真实的路径整合，必须将自身产生的感觉信号与外部诱导的感觉信号区分开来。预测编码被认为可以减弱自身引起的感觉反应，而任务相关性可以反转预测的减弱效应。但是，预测和任务需求如何影响自身运动处理，以及这些效应是否可以跨感觉通用？在这项 fMRI 研究中，我们研究了视觉和触觉自身运动处理及其受任务需求的调制。视觉刺激在地面上模拟向前的自身运动。触觉自身运动刺激通过气流传递到受试者的额头上。在一项任务中，受试者复制了之前观察到的被动自身位移的距离（复制/主动；高行为需求）（复制/被动）。在第二项任务中，受试者自行选择距离行进（自我/主动；低行为需求），并记录下来播放给他们（自我/被动）。对于两种任务和感觉模式，与被动试验相比，主动试验显示早期视觉区域增强，而顶下小叶（IPL）的高级区域抑制。对比高需求和低需求的主动试验在额前回产生超感觉增强。IPL 的抑制表明该区域是感觉自身运动信号及其预测的比较器。
