Centre of Biomedical Imaging and Translational Research (CIBIT), Institute of Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Portugal; Faculty of Medicine, University of Coimbra, Portugal.
Centre of Biomedical Imaging and Translational Research (CIBIT), Institute of Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Portugal.
Neuroimage. 2022 Oct 1;259:119403. doi: 10.1016/j.neuroimage.2022.119403. Epub 2022 Jun 20.
It remains to be understood how biological motion is hierarchically computed, from discrimination of local biological motion animacy to global dynamic body perception. Here, we addressed this functional separation of the correlates of the perception of local biological motion from perception of global motion of a body. We hypothesized that local biological motion processing can be isolated, by using a single dot motion perceptual decision paradigm featuring the biomechanical details of local realistic motion of a single joint. To ensure that we were indeed tackling processing of biological motion properties we used discrimination instead of detection task. We discovered using representational similarity analysis that two key early dorsal and two ventral stream regions (visual motion selective hMT+ and V3A, extrastriate body area EBA and a region within fusiform gyrus FFG) showed robust and separable signals related to encoding of local biological motion and global motion-mediated shape. These signals reflected two independent processing stages, as revealed by representational similarity analysis and deconvolution of fMRI responses to each motion pattern. This study showed that higher level pSTS encodes both classes of biological motion in a similar way, revealing a higher-level integrative stage, reflecting scale independent biological motion perception. Our results reveal a two-stage framework for neural computation of biological motion, with an independent contribution of dorsal and ventral regions for the initial stage.
目前尚不清楚生物运动是如何分层计算的，从局部生物运动能动性的辨别到整体动态身体感知。在这里，我们解决了局部生物运动感知与身体整体运动感知的相关物之间的这种功能分离。我们假设，通过使用具有单个关节局部真实运动生物力学细节的单个点运动感知决策范式，可以隔离局部生物运动处理。为了确保我们确实在处理生物运动特性的处理，我们使用了辨别而不是检测任务。我们发现，使用代表性相似性分析，两个关键的背侧和两个腹侧流区域（视觉运动选择性 hMT+和 V3A、外纹状区 EBA 和梭状回内的一个区域 FFG）显示出与局部生物运动和全局运动介导的形状编码相关的强大且可分离的信号。这些信号反映了两个独立的处理阶段，如代表性相似性分析和对每种运动模式的 fMRI 响应的反卷积所揭示的那样。这项研究表明，较高层次的 pSTS 以相似的方式对这两类生物运动进行编码，揭示了一个更高层次的综合阶段，反映了与尺度无关的生物运动感知。我们的结果揭示了生物运动神经计算的两阶段框架，背侧和腹侧区域对初始阶段有独立的贡献。
