Department of Psychology, "Sapienza" University of Rome, Rome, Italy; Department of Cognitive and Motor Rehabilitation and Neuroimaging, Santa Lucia Foundation (IRCCS Fondazione Santa Lucia), Rome, Italy.
Department of Psychology, "Sapienza" University of Rome, Rome, Italy; Department of Cognitive and Motor Rehabilitation and Neuroimaging, Santa Lucia Foundation (IRCCS Fondazione Santa Lucia), Rome, Italy.
Neuroimage. 2021 Dec 1;244:118581. doi: 10.1016/j.neuroimage.2021.118581. Epub 2021 Sep 17.
During real-world locomotion, in order to be able to move along a path or avoid an obstacle, continuous changes in self-motion direction (i.e. heading) are needed. Control of heading changes during locomotion requires the integration of multiple signals (i.e., visual, somatomotor, vestibular). Recent fMRI studies have shown that both somatomotor areas (human PEc [hPEc], human PE [hPE], primary somatosensory cortex [S-I]) and egomotion visual regions (cingulate sulcus visual area [CSv], posterior cingulate area [pCi], posterior insular cortex [PIC]) respond to either leg movements and egomotion-compatible visual stimulations, suggesting a role in the analysis of both visual attributes of egomotion and somatomotor signals with the aim of guiding locomotion. However, whether these regions are able to integrate egomotion-related visual signals with somatomotor inputs coming from leg movements during heading changes remains an open question. Here we used a combined approach of individual functional localizers and task-evoked activity by fMRI. In thirty subjects we first localized three egomotion areas (CSv, pCi, PIC) and three somatomotor regions (S-I, hPE, hPEc). Then, we tested their responses in a multisensory integration experiment combining visual and somatomotor signals relevant to locomotion in congruent or incongruent trials. We used an fMR-adaptation paradigm to explore the sensitivity to the repeated presentation of these bimodal stimuli in the six regions of interest. Results revealed that hPE, S-I and CSv showed an adaptation effect regardless of congruency, while PIC, pCi and hPEc showed sensitivity to congruency. PIC exhibited a preference for congruent trials compared to incongruent trials. Areas pCi and hPEc exhibited an adaptation effect only for congruent and incongruent trials, respectively. PIC, pCi and hPEc sensitivity to the congruency relationship between visual (locomotion-compatible) cues and (leg-related) somatomotor inputs suggests that these regions are involved in multisensory integration processes, likely in order to guide/adjust leg movements during heading changes.
在真实世界的运动中，为了能够沿着路径移动或避开障碍物，需要不断改变自我运动方向（即朝向）。运动中朝向变化的控制需要整合多种信号（即视觉、躯体感觉、前庭）。最近的 fMRI 研究表明，躯体感觉区域（人类 PEc[hPEc]、人类 PE[hPE]、初级躯体感觉皮层[S-I]）和自我运动视觉区域（扣带沟视觉区[CSv]、后扣带区[pCi]、后岛叶皮层[PIC]）都对腿部运动和自我运动兼容的视觉刺激有反应，这表明它们在分析自我运动的视觉属性和躯体感觉信号方面具有作用，目的是指导运动。然而，这些区域是否能够在朝向变化过程中整合与自我运动相关的视觉信号和来自腿部运动的躯体感觉输入仍然是一个悬而未决的问题。在这里，我们使用了个体功能定位器和 fMRI 任务诱发活动的组合方法。在三十名被试中，我们首先定位了三个自我运动区域（CSv、pCi、PIC）和三个躯体感觉区域（S-I、hPE、hPEc）。然后，我们在一个结合了与运动相关的视觉和躯体感觉信号的多感觉整合实验中测试了它们的反应，这些信号在一致或不一致的试验中是相匹配的。我们使用了 fMRI 适应范式来探索在六个感兴趣区域中重复呈现这些双模态刺激的敏感性。结果表明，hPE、S-I 和 CSv 表现出适应效应，而与一致性无关，而 PIC、pCi 和 hPEc 表现出对一致性的敏感性。与不一致的试验相比，PIC 对一致的试验表现出偏好。与视觉（运动兼容）线索和（腿部相关）躯体感觉输入之间的一致性关系相比，pCi 和 hPEc 仅表现出适应效应。PIC、pCi 和 hPEc 对视觉（运动兼容）线索和（腿部相关）躯体感觉输入之间的一致性关系的敏感性表明，这些区域参与了多感觉整合过程，可能是为了在朝向变化过程中指导/调整腿部运动。
