US-German Collaboration: Circuit models of form processing in primate V4

美德合作：灵长类动物形态处理的电路模型 V4

• 批准号: 1309725
• 负责人: Wyeth Bair
• 金额: $ 69.15万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-10-01 至 2016-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1309725&HistoricalAwards=false
• 关键词: US; German; Collaboration; Circuit; models

This collaborative study aims to advance the understanding of visual object recognition by combining electrophysiology, computational, modeling and psychophysics to probe the implications of newly discovered properties of neurons in visual cortical area V4, an important intermediate stage in the shape processing pathway of the brain.V4 neurons respond selectively to a variety of shape attributes, but recent studies demonstrate that they are also selective for the contrast polarity of stimuli and can be broadly classified into four categories based on their preference for the luminance contrast of shapes relative to a uniform background. Specifically, Equiluminance cells respond best to stimuli defined purely by a chromatic contrast with no luminance contrast while Bright, Dark and Contrast cells respond best to positive contrasts, negative contrasts or either, respectively. Because these categories are based on simple stimuli, it remains unknown how these cells respond to more naturalistic stimuli, where boundaries are seldom defined by a fixed luminance contrast, and whether the different cell classes have different functional roles for encoding objects. Characterizing V4 neurons with a parameterized set of naturalistic stimuli that are developed with rigorous psychophysical testing will provide novel insights into underlying circuitry and function and open new understanding about V4 and the ventral stream.Computational models of visual form processing in the brain have also been limited: they have not taken account of realistic physiological cell types known to exist from the retina to the visual cortex, they have been largely aimed at processing achromatic signals, and have relied heavily on feedfoward processing. This study will generate models that overcome these limitations and are invaluable for gaining insights into the circuits and mechanisms underlying form processing. These models will be available in an open, online framework designed to set a standard for ease of use and transparency, to spur further collaboration between theoreticians and experimentalists, and to facilitate education.Finally, there has been a longstanding debate in vision science, motivated from the psychophysical literature, that questions whether and how chromatic signals contribute to form processing. The traditional view has been that boundary detection and segmentation are solely based on luminance contrast. Color then paints a surface within the confines of the identified boundary. Recent psychophysical and theoretical studies are at odds with this view and argue that color is important for segmentation and form processing in natural scenes, for example, fruit amidst leaves, where detection based on luminance contrast is very difficult. The experiments in this study will inject much needed physiology data into this debate and the models developed here will shed light on the functional organization of cortical pathways at multiple stages, revealing how different aspects of our natural visual input contribute to form perception.This award is being co-funded by NSF's Office of the Director, International Science and Engineering. A companion project is being funded by the German Ministry of Education and Research (BMBF).

这项合作研究旨在通过结合电生理学，计算，建模和心理物理学来促进对视觉物体识别的理解，以探索视觉皮层V4区神经元新发现的特性的含义，V4区是大脑形状加工途径的重要中间阶段。V4神经元选择性地对各种形状属性做出反应，但是最近的研究表明，它们对于刺激的对比极性也是有选择性的，并且可以基于它们对于形状相对于均匀背景的亮度对比度的偏好而被广泛地分为四类。 具体地，均衡亮度单元对纯粹由没有亮度对比的色彩对比定义的刺激响应最佳，而亮、暗和对比单元分别对正对比、负对比或其中之一响应最佳。 由于这些类别是基于简单的刺激，它仍然是未知的，这些细胞如何响应更自然的刺激，其中边界很少被定义为一个固定的亮度对比度，以及是否不同的细胞类编码对象有不同的功能角色。通过严格的心理物理学测试开发的一组参数化的自然刺激来表征V4神经元，将为潜在的电路和功能提供新的见解，并开启对V4和腹侧流的新理解。大脑中视觉形式处理的计算模型也受到限制：它们没有考虑到已知存在于从视网膜到视觉皮层的实际生理细胞类型，它们主要针对处理非彩色信号，并且严重依赖于前馈处理。 这项研究将产生模型，克服这些限制，并获得深入了解电路和机制的形式处理是非常宝贵的。这些模型将在一个开放的在线框架中提供，旨在为易用性和透明度设定标准，以促进理论家和实验家之间的进一步合作，并促进教育。最后，视觉科学中存在着一个长期的争论，其动机来自心理物理学文献，即彩色信号是否以及如何有助于形状处理。传统的观点认为，边界检测和分割是完全基于亮度对比度。然后，颜色在所标识的边界范围内绘制曲面。最近的心理物理和理论研究与这种观点不一致，并认为颜色对于自然场景中的分割和形状处理很重要，例如树叶中的水果，其中基于亮度对比度的检测非常困难。这项研究中的实验将为这场辩论注入急需的生理学数据，这里开发的模型将揭示皮层通路在多个阶段的功能组织，揭示我们自然视觉输入的不同方面如何有助于形成感知。该奖项由NSF国际科学与工程主任办公室共同资助。 德国教育和研究部（BMBF）正在资助一个配套项目。