Department of Psychology, Justus Liebig University Giessen, Giessen 35394, Germany.
Department of Psychology, Justus Liebig University Giessen, Giessen 35394, Germany; Department of Psychology, A.S. Brain Research Center, and National Magnetic Resonance Research Center (UMRAM), Bilkent University, Ankara 06800, Turkey.
Neuroimage. 2021 Mar;228:117688. doi: 10.1016/j.neuroimage.2020.117688. Epub 2020 Dec 29.
There is growing research interest in the neural mechanisms underlying the recognition of material categories and properties. This research field, however, is relatively more recent and limited compared to investigations of the neural mechanisms underlying object and scene category recognition. Motion is particularly important for the perception of non-rigid materials, but the neural basis of non-rigid material motion remains unexplored. Using fMRI, we investigated which brain regions respond preferentially to material motion versus other types of motion. We introduce a new database of stimuli - dynamic dot materials - that are animations of moving dots that induce vivid percepts of various materials in motion, e.g. flapping cloth, liquid waves, wobbling jelly. Control stimuli were scrambled versions of these same animations and rigid three-dimensional rotating dots. Results showed that isolating material motion properties with dynamic dots (in contrast with other kinds of motion) activates a network of cortical regions in both ventral and dorsal visual pathways, including areas normally associated with the processing of surface properties and shape, and extending to somatosensory and premotor cortices. We suggest that such a widespread preference for material motion is due to strong associations between stimulus properties. For example viewing dots moving in a specific pattern not only elicits percepts of material motion; one perceives a flexible, non-rigid shape, identifies the object as a cloth flapping in the wind, infers the object's weight under gravity, and anticipates how it would feel to reach out and touch the material. These results are a first important step in mapping out the cortical architecture and dynamics in material-related motion processing.
人们对物质类别和属性识别的神经机制越来越感兴趣。然而，与对物体和场景类别识别的神经机制的研究相比，这个研究领域相对较新且有限。运动对于非刚性物质的感知尤为重要，但非刚性物质运动的神经基础仍未被探索。我们使用 fMRI 研究了大脑中哪些区域对物质运动有优先反应，而不是其他类型的运动。我们引入了一个新的刺激数据库 - 动态点材料 - 这些是移动点的动画，它们可以生动地感知运动中的各种物质，例如飘动的布料、液体波浪、摇晃的果冻。控制刺激是这些相同动画的随机版本和刚性三维旋转点。结果表明，用动态点分离物质运动特性（与其他类型的运动相比）会激活腹侧和背侧视觉通路中的皮质区域网络，包括通常与表面特性和形状处理相关的区域，并延伸到体感和运动前皮质。我们认为，这种对物质运动的广泛偏好是由于刺激特性之间的强烈关联。例如，观看以特定模式移动的点不仅会引起物质运动的感知；人们会感知到一个灵活的、非刚性的形状，识别出风中飘动的布料，推断出物体在重力下的重量，并预测伸出手触摸材料的感觉。这些结果是描绘与物质相关的运动处理中皮质结构和动力学的重要第一步。
