Role of area V4 in the perception of partially occluded objects

V4 区在部分遮挡物体感知中的作用

• 批准号: 8448292
• 负责人: Anitha Pasupathy
• 金额: $ 37.75万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-04-01 至 2015-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8448292
• 关键词: Animals; Back; Behavior; Behavioral; Brain; Brain Diseases; Cells; Code; Complex; Cues; Decision Making; Discrimination; Environment; Exhibits; Eye; Functional disorder; Goals; Health; Human; Image; Image Analysis; Laboratories; Lesion; Monkeys; Neurons; Pathway interactions; Pattern; Perception; Play; Population; Primates; Probability; Process; Property; Psychologist; Psychophysics; Relative (related person); Research; Retina; Retinal; Role; Shapes; Signal Transduction; Source; Staging; Stimulus; Testing; Theoretical Studies; Tight Junctions; Time; V4 neuron; Visual; Visual Agnosias; Visual Pathways; Visual system structure; area V4; awake; discount; feeding; inferotemporal cortex; man; neuromechanism; neurophysiology; object recognition; object shape; psychologic; relating to nervous system; research study; response; sample fixation; shape analysis; two-dimensional; visual information; visual process; visual processing; visual stimulus

Description (provided by applicant): The human visual system rapidly, accurately, and seemingly effortlessly, recognizes objects that are partially occluded. The long-term goal of research in my laboratory is to determine how this is achieved by the primate visual system. Previous research has demonstrated that visual information that reaches our eyes is processed along the multi-stage ventral "shape processing" pathway. We will investigate the contributions of area V4, an intermediate stage in this pathway, to the processing of partial occlusion. When the three-dimensional world casts a two-dimensional image on the retina, objects that are closer to the viewer partially or completely occlude objects that are farther away. This causes two types of distortions in the retinal image. First, partial occlusions produce "accidental" contour features due to the accidental juxtaposition of the bounding contours of the occluded and occluding objects. Second, parts of the occluded object are missing and may even be fragmented in the retinal image. To accurately recognize the occluded object despite partial occlusion, the visual system needs to discount the accidental contour features and then sew together the fragmented parts by amodally completing the missing contours. Psychological and theoretical evidence suggests that analysis of image features at the intersecting junctions of the occluded and occluding contours (T-like junctions) in the early stages of visual processing underlies processing of occlusion but the neural mechanisms are unknown. Evidence from lesion studies and neurophysiological studies suggest that area V4 is likely to play an important role. A competing hypothesis proposes that occlusion is inferred as a result of robust recognition of objects from their fragmented parts in the highest stages of processing such as inferotemporal cortex. The two hypotheses make distinct predictions about the patterns of responses in area V4. We will conduct single cell recordings of V4 neurons in awake primates performing fixation and behavioral tasks. In aim 1, we will investigate if V4 responses support differential processing of real and accidental contour features. In aim 2, we will investigate if amodal completion signals in area V4 appear before or after accurate recognition of the partially occluded object. Results from these experiments will determine which of the above hypotheses is supported in the primate brain. It will also identify V4 neural mechanisms that contribute to inference about partial occlusion. Object recognition is impaired in visual agnosia, a dysfunction of the occipitotemporal pathway. Results from the proposed experiments will constitute a major advance in our understanding of the brain computations that underlie object recognition and will bring us closer to devising strategies to alleviate and treat this brain disorder.

描述（由申请人提供）：人类视觉系统迅速，准确且看似毫不费力地识别出部分遮挡的对象。我的实验室研究的长期目标是确定灵长类动物视觉系统如何实现这一目标。先前的研究表明，到达我们眼睛的视觉信息沿多阶段的腹侧“形状处理”途径进行处理。我们将调查V4区域（该途径中的中间阶段）对部分闭塞处理的贡献。当三维世界在视网膜上施放二维图像时，靠近观众的物体部分或完全遮住了较远的物体。这会导致视网膜图像中两种类型的扭曲。首先，部分阻塞产生了“意外”轮廓特征，这是由于被遮挡和阻塞物体的边界轮廓的意外并置。其次，被阻塞物体的一部分缺失，甚至可能在视网膜图像中分散。要准确地识别出遮挡的物体，尽管部分阻塞，视觉系统需要打折意外轮廓功能，然后通过毫无疑问完成缺失的轮廓来缝制零碎的零件。心理和理论证据表明，在视觉处理的早期阶段，对遮挡和阻塞轮廓的相交连接处的图像特征的分析是闭塞的构成的基础，但神经机制是未知的。病变研究和神经生理学研究的证据表明，V4区域可能起重要作用。一个竞争的假设提出，由于对物体从其零散的部分中的碎片识别在加工的最高阶段（例如颞叶皮层）中，推断了遮挡。这两个假设对区域V4中响应模式做出了不同的预测。我们将在执行固定任务和行为任务的清醒灵长类动物中进行V4神经元的单细胞记录。在AIM 1中，我们将研究V4响应是否支持对真实和意外轮廓特征的差异处理。在AIM 2中，我们将调查V4区域中Amodal完成信号是否在对部分遮挡的对象进行准确识别之前或之后出现。这些实验的结果将确定灵长类动物大脑中支持上述哪些假设。它还将确定有助于部分闭塞推论的V4神经机制。在视觉不症中，对象识别受损，这是枕颞途径的功能障碍。拟议的实验的结果将构成我们对基于对象识别的大脑计算的理解的重大进步，并将使我们更接近制定减轻和治疗这种脑部疾病的策略。