Department of Movement, Human and Health Sciences, University of Rome ''Foro Italico'', Rome, Italy; Department of Cognitive and Motor Rehabilitation and Neuroimaging, Santa Lucia Foundation (IRCCS Fondazione Santa Lucia), Rome, Italy.
Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.
Cortex. 2021 Apr;137:74-92. doi: 10.1016/j.cortex.2020.12.021. Epub 2021 Jan 23.
During locomotion, leg movements define the direction of walking (forward or backward) and the path one is taking (straight or curved). These aspects of locomotion produce characteristic visual motion patterns during movement. Here, we tested whether cortical regions responding to either egomotion-compatible visual motion, or leg movements, or both, are sensitive to these locomotion-relevant aspects of visual motion. We compared a curved path (typically the visual feedback of a changing direction of movement in the environment) to a linear path for simulated forward and backward motion in an event-related fMRI experiment. We used an individual surface-based approach and two functional localizers to define (1) six egomotion-related areas (V6+, V3A, intraparietal motion area [IPSmot], cingulate sulcus visual area [CSv], posterior cingulate area [pCi], posterior insular cortex [PIC]) using the flow field stimulus and (2) three leg-related cortical regions (human PEc [hPEc], human PE [hPE] and primary somatosensory cortex [S-I]) using a somatomotor task. Then, we extracted the response from all these regions with respect to the main event-related fMRI experiment, consisting of passive viewing of an optic flow stimulus, simulating a forward or backward direction of self-motion in either linear or curved path. Results showed that some regions have a significant preference for the curved path motion (hPEc, hPE, S-I, IPSmot) or a preference for the forward motion (V3A), while other regions have both a significant preference for the curved path motion and for the forward compared to backward motion (V6+, CSv, pCi). We did not find any significant effects of the present stimuli in PIC. Since controlling locomotion mainly means controlling changes of walking direction in the environment during forward self-motion, such a differential functional profile among these cortical regions suggests that they play a differentiated role in the visual guidance of locomotion.
在运动过程中，腿部运动定义了行走的方向（向前或向后）和行走的路径（直的或弯的）。这些运动方面在运动过程中产生特征性的视觉运动模式。在这里，我们测试了响应于自运动兼容的视觉运动、腿部运动或两者的皮质区域是否对视觉运动的这些与运动相关的方面敏感。我们比较了模拟向前和向后运动的弯曲路径（通常是环境中运动方向变化的视觉反馈）和直线路径，在事件相关 fMRI 实验中。我们使用个体表面方法和两个功能定位器来定义（1）六个与自运动相关的区域（V6+、V3A、顶内运动区[IPSmot]、扣带回视觉区[CSv]、后扣带回区[pCi]、后岛叶皮层[PIC]），使用流场刺激，（2）三个与腿部相关的皮质区域（人类小脑顶核[hPEc]、人类小脑[hPE]和初级躯体感觉皮层[S-I]），使用躯体运动任务。然后，我们从所有这些区域提取了相对于主要事件相关 fMRI 实验的反应，该实验由被动观看光流刺激组成，模拟了线性或弯曲路径中自我运动的向前或向后方向。结果表明，一些区域对弯曲路径运动有显著偏好（hPEc、hPE、S-I、IPSmot）或对向前运动有偏好（V3A），而其他区域对弯曲路径运动和向前运动都有显著偏好与向后运动相比（V6+、CSv、pCi）。我们没有发现 PIC 中当前刺激的任何显著影响。由于控制运动主要意味着在向前自我运动期间控制环境中行走方向的变化，因此这些皮质区域之间的这种差异功能谱表明它们在运动的视觉引导中发挥了不同的作用。
