Graduate Program in Neuroscience, University of Washington, Seattle, WA 98195, USA; Department of Biological Structure and Washington National Primate Research Center, University of Washington, Seattle, WA 98195, USA.
Department of Biological Structure and Washington National Primate Research Center, University of Washington, Seattle, WA 98195, USA.
Curr Biol. 2023 Feb 27;33(4):711-719.e5. doi: 10.1016/j.cub.2023.01.016. Epub 2023 Feb 3.
A paradox exists in our understanding of motion processing in the primate visual system: neurons in the dorsal motion processing stream often strikingly fail to encode long-range and perceptually salient jumps of a moving stimulus. Psychophysical studies suggest that such long-range motion, which requires integration over more distant parts of the visual field, may be based on higher-order motion processing mechanisms that rely on feature or object tracking. Here, we demonstrate that ventral visual area V4, long recognized as critical for processing static scenes, includes neurons that maintain direction selectivity for long-range motion, even when conflicting local motion is present. These V4 neurons exhibit specific selectivity for the motion of objects, i.e., targets with defined boundaries, rather than the motion of surfaces behind apertures, and are selective for direction of motion over a broad range of spatial displacements and defined by a variety of features. Motion direction at a range of speeds can be accurately decoded on single trials from the activity of just a few V4 neurons. Thus, our results identify a novel motion computation in the ventral stream that is strikingly different from, and complementary to, the well-established system in the dorsal stream, and they support the hypothesis that the ventral stream system interacts with the dorsal stream to achieve the higher level of abstraction critical for tracking dynamic objects.
背侧运动处理流中的神经元经常明显无法编码运动刺激的长距离和明显的跳跃。心理物理学研究表明，这种长距离运动需要在视野的更远部分进行整合，可能基于依赖于特征或物体跟踪的更高阶运动处理机制。在这里，我们证明，腹侧视觉区域 V4 长期以来被认为对处理静态场景至关重要，其中包括对长距离运动保持方向选择性的神经元，即使存在冲突的局部运动。这些 V4 神经元对物体的运动表现出特定的选择性，即具有定义边界的目标，而不是孔径后面的表面的运动，并且对运动方向具有广泛的空间位移选择性，并由各种特征定义。在单个试验中，仅从少数几个 V4 神经元的活动中就可以准确地解码运动方向。因此，我们的结果确定了腹侧流中的一种新的运动计算，与背侧流中已建立的系统明显不同且互补，并支持腹侧流系统与背侧流系统相互作用以实现跟踪动态物体所需的更高抽象水平的假设。
