Spatiotemporal representation in ventral visual pathway

腹侧视觉通路的时空表征

• 批准号: 10525256
• 负责人: Anitha Pasupathy
• 金额: $ 45.78万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-02-01 至 2025-11-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10525256
• 关键词: Aging; Alzheimer' s Disease; Animals; Appearance; Area; Articular Range of Motion; Behavior; Biological; Characteristics; Complex; Cues; Custom; Data; Dorsal; Environment; Foundations; Impairment; Individual; Investigation; Macaca; Methods; Modeling; Monkeys; Motion; Motion Perception; Neurons; Pathway interactions; Perception; Play; Population; Primates; Process; Psychophysics; Reaction Time; Role; Rotation; Shapes; Signal Transduction; Source; Speed; Stimulus; Stream; Testing; Time; Translating; Translations; V4 neuron; Vision; Visual; Visual Cortex; Visual Fields; Visual Motion; Visual Pathways; Visual System; area MT; area V4; awake; behavioral study; density; design; experimental study; inferotemporal cortex; insight; neurophysiology; novel; object motion; object shape; receptive field; response; retinal imaging; sample fixation; spatiotemporal; temporal measurement; visual information; visual processing; visual stimulus

In natural vision, objects change appearance over time as they translate, rotate, become occluded or undergo complex transformations, e.g., during biological motion. In these dynamic environments, the visual cortex integrates information over multiple spatial and temporal scales to compute motion trajectories and represent the shape of objects. To understand how form and motion percepts are derived from such dynamic visual input, we will investigate how neuronal responses in area V4—an intermediate stage along the ventral visual pathway—are shaped by the spatiotemporal integration of time-varying visual stimuli. We will test the hypothesis that the spatiotemporal characteristics of V4 neurons are suited for tracking dynamic objects: specifically, V4 motion signals arise from object-tracking over longer spatiotemporal windows than comparable dorsal-stream areas and that V4 signals reflect form transformations at an object level rather than at the level of the local retinal image. We will leverage the percept of long-range apparent motion to probe the role of V4 neurons in motion perception (Aim 1). When a stimulus intermittently skips across the visual field with large spatial and temporal steps, it induces a strong illusory motion percept but neurons in V1 and MT of the dorsal visual stream are strikingly insensitive to the direction of the perceived motion. Psychophysical studies have argued that long-range apparent motion relies not on the dorsal stream but on higher order object tracking processes with large spatiotemporal windows in the ventral visual stream. We will conduct the first neurophysiological investigations in the awake monkey to ascertain the role of V4 in the perception of long- range apparent motion. Next (Aim 2), we will use dynamic stimuli that rotate in the fronto-parallel plane, and translate and rotate in depth, to determine whether V4 neurons encode other common dynamic object transformations (beyond long-range translation), and whether the encoding is based on a sequence of static poses, as in the inferotemporal (IT) cortex, or dynamic transformations. Finally, we will examine the encoding and perception of partially occluded dynamic objects (Aim 3). When an occluded object moves, different parts of the object are revealed over time and integration across time and multiple neuronal receptive fields is required to build an entire object representation. As animals discriminate moving occluded objects, we will study 50-100 neurons with high-density Neuropixels probes. We will use single trial population decoding methods to determine how dynamic stimulus information is integrated across the V4 network to extract object shape and the motion trajectory and how V4 contributes to psychophysical behavior. We anticipate that our results will reveal an important role for V4 in the processing of dynamic stimuli that is complementary to those of MT and IT cortex and will establish the level of internal visual representation operating in V4. Our studies will provide a deeper understanding of the neuronal basis of global motion perception and the tracking of dynamic objects—processes that are impaired in aging populations, especially those with Alzheimer’s disease.

在自然视觉中，物体随着时间的推移而改变外观，因为它们平移，旋转，被遮挡或经历 复杂的变换，例如，在生物运动中。在这些动态的环境中，视觉皮层 整合多个空间和时间尺度上的信息，以计算运动轨迹并表示 物体的形状。为了理解形式和运动感知是如何从这样的动态视觉中产生的， 输入，我们将研究如何在V4区的神经反应-一个中间阶段，沿腹侧视觉沿着 路径-由时变视觉刺激的时空整合形成。我们将测试 假设V4神经元的时空特性适合于跟踪动态对象： 具体地说，V4运动信号是由在比可比较的更长的时空窗口上的对象跟踪产生的 背流区和V4信号反映形式转换在对象水平，而不是在水平 局部视网膜图像。我们将利用长程视运动的概念来探讨V4的作用 运动知觉中的神经元（Aim 1）。当刺激间歇性地跳过视野时， 空间和时间的步骤，它诱导了强烈的错觉运动感受，但在V1和MT的背侧神经元 视觉流对所感知的运动的方向显著不敏感。心理物理学研究 他认为，长距离视运动不依赖于背流，而是依赖于高阶物体跟踪 在腹侧视觉流中具有大的时空窗口的过程。我们将进行第一次 在清醒的猴子的神经生理学调查，以确定V4的作用，在长期的感知， 距离视动接下来（目标2），我们将使用在额平行平面内旋转的动态刺激， 在深度上平移和旋转，以确定V4神经元是否编码其他常见的动态对象 转换（超出长距离转换），以及编码是否基于静态 姿势，如在下颞（IT）皮层，或动态变换。最后，我们将检查编码 和感知部分被遮挡的动态对象（目标3）。当被遮挡的物体移动时， 随着时间的推移，对象的显示和跨时间的整合和多个神经元感受野， 需要构建整个对象表示。当动物辨别移动的被遮挡物体时，我们将 用高密度Neuropixels探针研究50-100个神经元。我们将使用单次试验群体解码 确定如何通过V4网络整合动态刺激信息以提取对象的方法 形状和运动轨迹以及V4如何影响心理物理行为。我们预计， 结果将揭示V4在处理动态刺激中的重要作用，这是对这些刺激的补充。 的MT和IT皮层，并将建立在V4操作的内部视觉表征的水平。我们的研究将 提供了一个更深入的了解神经基础的全球运动感知和跟踪的动态 对象-在老龄化人群中受损的过程，特别是那些患有阿尔茨海默病的人。