Neurophysiology of Visual Perception

视觉感知的神经生理学

• 批准号: 10012698
• 负责人: David A Leopold
• 金额: $ 95.78万
• 依托单位: NATIONAL INSTITUTE OF MENTAL HEALTH
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10012698
• 关键词: Anger; Animals; Architecture; Area; Behavior; Brain; Cells; Childhood; Complex; Data; Dimensions; Dorsal; Elements; Environment; Esthesia; Exhibits; Eye; Face; Facial Expression; Faculty; Functional Magnetic Resonance Imaging; Hand; Human; Image; Inherited; Instinct; Knowledge; Liquid substance; Macaca; Manuals; Manuscripts; Maps; Measures; Mental disorders; Methods; Movement; Music; Nature; Neurons; Neurosciences; Nuclear; Organ; Paper; Partner in relationship; Pathway interactions; Perception; Persons; Play; Population; Preparation; Process; Publishing; Pulvinar structure; Reading; Research; Research Personnel; Resolution; Response Latencies; Rest; Retina; Retinal; Role; Running; Scanning; Seeds; Sensory; Series; Shapes; Signal Transduction; Social Interaction; Spatial Distribution; Sports; Stimulus; Structure; Temporal Lobe; Testing; Time; Vision; Visual; Visual Cortex; Visual Pathways; Visual Perception; Work; base; distraction; experience; experimental study; gaze; grasp; human model; instrument; movie; nervous system disorder; neurophysiology; operation; programs; relating to nervous system; response; retinal imaging; skills; social; symposium; tool; visual stimulus

Humans are fully committed to the use of vision for their social interaction. For example, the extended childhood of humans teaches us to read very subtle facial expressions that can tell us whether a person is lying, angry, embarrassed, skeptical, or in a hurry. Further, vision is at the center of another important human skill: the capacity to use our hands in countless ways. Not only do we use vision to direct our hands during social interaction, but we are also able take this much further in the use of tools, participation in sports, or the playing musical instruments. This human exceptionalism rests atop an impressive visual repertoire shared by many other mammalian species, who use often use vision to recognize territories, build nests, avoid predators, and find mates. While these everyday problems of animals are sometimes downplayed by researchers as simply involving innate behaviors, the visual problems involved are often highly complex and share much in common with human vision. While much has been learned about the visual brain, many of the basic problems of vision, and their bearing on how we see and interpret others and the world around us, remain poorly understood. Much of our experimental work on visual perception centers on how the brain analyzes social stimuli and scenes. For vision, this process necessarily begins in the retina, whose contents are interpreted though a series of highly specialized cortical areas. The brain uses this information not only to recognize objects, but also to create a three-dimensional, internal representation of the world for perception and action. It performs this operation fluidly, maintaining a stable visual scene while somehow resisting distraction by the continuous retinal disturbances caused by our own movements, most notably changes in eye gaze. In one major project, we have been investigating how neurons in the macaque temporal cortex respond during free-running paradigm that depart from the conventional mode of testing, which is the serial presentation of briefly flashed image stimuli. During this testing, we allow subjects to view natural videos playing out over several minutes at a time. Subjects are free to scan the content of the videos, as we record their gaze and the activity of many neurons in different regions of the high-level visual cortex. Our analysis also departs from convention in that we do not focus on stimulus representation per se, but rather on how different parts of the brain work together in processing different types of scenes. For this, we combined our multiple single-unit recordings with data from functional MRI (fMRI), in which macaque subjects watched the same natural videos. Given the full-brain coverage afforded by fMRI, we were then able obtain whole-brain maps of fMRI data using single-unit activity as a sort of seed or regressor. The first paper using this method was published emphasized the local response diversity within a local population of temporal cortex neurons. Perhaps most surprisingly, it demonstrated that neighboring neurons participated in very different whole-brain networks when analyzed through the seed correlation method mentioned above. A second manuscript on this topic, comparing local populations in multiple temporal cortex areas, is currently under preparation. In another project, we have investigated the nature of the temporal structure during the flow of a natural scene. Specifically, we have asked the question whether the temporal dynamics are themselves important for determining in neural selectivity. To this end, we extracted one-second segments from a continuous movie and compared the neural responses to the extracted components to those arising when the movie was shown intact. Our results indicate that temporal integration from moment to moment is an important determinant in the firing of many neurons. Further, the initial visual response transient showed a stimulus tuning that was uncorrelated with the neurons response to the same moments of the intact movie. This latter finding was very surprising and may have profound consequences for how we think about the visual brain, since most of our understanding of the cortical microcircuit, visual hierarchy, stimulus selectivity, and functional architecture are derived from experiments in which stimuli were flashed briefly onto a screen. In our studies of the pulvinar, we have continued to investigate the spatial distribution of neurons responsive to particular visual features across this large nuclear complex. In one study, we measured a concentration of neurons in and around the corticotectal tract that are notably selective for faces. In a manuscript currently under preparation, we have compared the nature of these face-selective responses with so-called face-cells in the fMRI mapped face patches of the temporal cortex. One of the principal findings is that many of the pulvinar face-selective neurons respond much earlier than the earliest responses in the face patches, suggesting that their face selectivity cannot be simply inherited from those areas. In another study, we measured the responses of pulvinar neurons to natural videos, as described above for face patches. We found a number of pulvinar neurons that exhibit similar time courses and fMRI-mapping profiles to the face patch neurons. This observation, together with their very short response latencies, raises important questions about the role of the pulvinar in the processing of certain, specialized stimuli such as faces. One possibility is that pulvinar neurons have two important roles: first, they pass such visual signals up to the cortex through a secondary visual pathway, and second they receive ample cortical input to coordinate the fast pulvinar pathway with the slower geniculocortical pathway.

人类完全致力于利用视觉进行社交。例如，人类漫长的童年教会我们阅读非常微妙的面部表情，这些表情可以告诉我们一个人是在撒谎、愤怒、尴尬、怀疑还是匆忙。此外，视觉是另一项重要的人类技能的核心：以无数种方式使用我们的手的能力。我们不仅在社交中使用视觉来指导我们的手，而且我们还能够在使用工具、参与体育运动或演奏乐器方面取得更大的进步。 这一人类例外论建立在许多其他哺乳动物共有的令人印象深刻的视觉技能之上，这些哺乳动物经常使用视觉来识别领土、筑巢、躲避捕食者和寻找配偶。虽然研究人员有时会淡化动物的这些日常问题，认为这只是与生俱来的行为，但涉及的视觉问题往往非常复杂，与人类的视觉有许多相似之处。虽然人们已经对视觉大脑有了很多了解，但视觉的许多基本问题，以及它们对我们如何看待和解释他人和我们周围世界的影响，仍然知之甚少。 我们在视觉感知方面的大部分实验工作都集中在大脑如何分析社会刺激和场景。对于视觉来说，这一过程必然始于视网膜，视网膜的内容通过一系列高度专业化的皮质区域进行解释。大脑不仅使用这些信息来识别物体，还使用这些信息来创建三维的、内部的世界表示，用于感知和行动。它流畅地执行这一操作，保持稳定的视觉场景，同时以某种方式抵抗由我们自己的运动引起的持续视网膜干扰而分散注意力，最明显的是眼睛凝视的变化。 在一个重大项目中，我们一直在研究猕猴颞叶皮质神经元在自由运行范式中的反应，这种范式偏离了传统的测试模式，即短暂闪光图像刺激的连续呈现。在这项测试中，我们允许受试者一次观看几分钟内播放的自然视频。受试者可以自由地浏览视频内容，因为我们记录了他们的凝视和高级视觉皮质不同区域中许多神经元的活动。我们的分析也偏离了惯例，因为我们不关注刺激表示本身，而是关注大脑的不同部分如何在处理不同类型的场景时协同工作。为此，我们将我们的多个单单元记录与功能磁共振成像(FMRI)的数据相结合，在功能磁共振成像中，猕猴受试者观看相同的自然视频。有了fMRI提供的全脑覆盖，我们就能够使用单个单位的活动作为种子或回归变量来获得fMRI数据的全脑图。第一篇使用这种方法的论文发表时强调了在局部的颞叶皮质神经元群体中的局部反应的多样性。也许最令人惊讶的是，当通过上面提到的种子相关方法进行分析时，它证明了相邻的神经元参与了非常不同的全脑网络。关于这一主题的第二份手稿，比较了多个颞叶皮质区域的当地人口，目前正在准备中。 在另一个项目中，我们研究了自然场景流动过程中时间结构的性质。具体地说，我们提出了这样一个问题：时间动力学本身是否对神经选择性的决定很重要。为此，我们从一部连续的电影中提取了一秒钟的片段，并将对提取的成分的神经反应与电影完整放映时产生的神经反应进行了比较。我们的结果表明，瞬间到瞬间的时间整合是许多神经元放电的重要决定因素。此外，最初的视觉反应瞬变显示出与神经元对完整电影中相同时刻的反应无关的刺激调节。后一项发现非常令人惊讶，可能会对我们如何看待视觉大脑产生深远的影响，因为我们对皮质微电路、视觉层次、刺激选择性和功能结构的大多数理解都来自于刺激短暂闪现到屏幕上的实验。 在我们对枕骨的研究中，我们继续研究对这个大型核复合体中特定视觉特征做出反应的神经元的空间分布。在一项研究中，我们测量了皮质顶盖内束及其周围的神经元浓度，这些神经元对面部有明显的选择性。在目前正在准备的一份手稿中，我们将这些面部选择性反应的性质与颞叶皮质fMRI映射的面部斑块中的所谓面部细胞进行了比较。其中一个主要发现是，许多枕部面部选择性神经元的反应比面部斑块中最早的反应早得多，这表明它们的面部选择性不能简单地从这些区域遗传过来。在另一项研究中，我们测量了枕部神经元对自然视频的反应，就像上面针对面部贴片所描述的那样。我们发现一些枕区神经元表现出与面部斑块神经元相似的时间进程和功能磁共振成像图谱。这一观察结果，加上他们非常短的反应潜伏期，提出了关于枕骨在处理某些特定的刺激，如面部的作用的重要问题。一种可能性是，枕叶神经元有两个重要的作用：第一，它们通过第二视觉通路将这种视觉信号传递到大脑皮层，第二，它们接受充足的皮质输入，以协调快速的枕叶通路和较慢的膝皮质通路。