Neurophysiology of Visual Perception

视觉感知的神经生理学

基本信息

批准号：
8342147
负责人：
David A Leopold
金额：
$ 63.32万
依托单位：
NATIONAL INSTITUTE OF MENTAL HEALTH
依托单位国家：
美国
项目类别：
财政年份：
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/8342147
关键词：
Ablation Affect Area Behavior Behavioral Brain Cell Nucleus Cerebral cortex Cognitive Color Complex Conscious Disease Drops Elements Emotional Environment Event Face Functional Magnetic Resonance Imaging Human Image Individual Injury Investigation Lateral Geniculate Body Lead Left Lesion Light Methods Modeling Monkeys Movement Neurons Pathway interactions Patients Pattern Perception Positioning Attribute Primates Process Psychology Publishing Pulvinar structure Reporting Residual state Response to stimulus physiology Retina Retinal Shapes Stimulus Structure Study models Testing Textbooks Thalamic Nuclei Thalamic structure Time Training Unconscious State Ursidae Family Vision Visual Visual Cortex Visual Fields Visual Perception Visually Impaired Persons Writing area striata base blind detector experience extrastriate visual cortex falls gaze impression neural circuit neuromechanism neurophysiology nonhuman primate receptor relating to nervous system response three dimensional structure visual information visual performance visual stimulus

项目摘要

Our visual perception of the world around us is so immediate and intuitive that it is not obvious that the brain needs to solve any problem at all. However, more than 50% of the cerebral cortex, the prominent outer covering of the brain, is devoted to seeing. Humans and other primates rely more heavily on vision than any other sense to interact with the environment and with each other. Each time we redirect our gaze, an event that happens several times per second, our retinal receptors are confronted with a new pattern of light, dark, and colors. It is up to our brain to decode, interpret, and act upon this information. The incapacity to appropriately interpret retinal information correctly underlies a range of serious deficits. At one end of the spectrum, individuals are blind and must rely on other senses to survive. At the other end, their basic vision is normal, but they are apt to misjudge distances, or misinterpret the identity, emotional state, or intentions of other individuals. Studying the basic mechanisms by which the brain decodes and interprets the information inherent in the retinal image is central to understanding the most impressive and important functions of the human brain. The project entitled Neurophysiology of Visual Perception has two components, each of which uses the nonhuman primate model to understand the neural basis of human visual perception. We combine the most modern electrophysiological recordings, functional magnetic resonance imaging (fMRI), and reversible local inactivation in monkeys, allowing us to isolate and study mechanisms related to specific aspects of vision. The first component focuses on the so-called primitives of vision lines, colors, shapes, and movements to understand how more complex perceptions are assembled from basic building blocks. This is the first task of the visual brain, and its core principles remain poorly understood. In a sense, all information on the retina is in a primitive state, as patterns activate light detectors sensitive to different colors and positions. The cerebral cortex then extracts somewhat higher primitives, such as orientations, directions of movements, and shapes of contours, as evidenced by the types of visual stimuli to which neurons there respond. Under some circumstances, visual primitives can be arranged to inherently ambiguous in their perceptual interpretation. When confronted with inherently ambiguous stimuli, perception fluctuates between two alternative impressions. That is, it becomes bistable. Famous bistable figures from psychology textbooks include the Necker cube and Rubins Face vs. Vase stimulus, though there are literally hundreds of examples. In the past years we have trained nonhuman primates to report which of two perceptual interpretations is visible at each time point. The monkeys report this information by pulling one of two levers in their primate chair. Based on these behavioral responses, we are then able to study which aspects of brain activity, in which cortical areas, follow the monkeys subjective perceptual state. Note that this question deviates from more conventional investigations, where neural responses are tracked as a function of stimulus features. In this case, the stimulus is always identical, but the monkeys perception changes. Recently, we found that the visual thalamus, a large relay structure in the middle of the brain that interacts strongly with the cerebral cortex, shows activity changes that reflect the monkeys perceptual state. More specifically, the pulvinar nucleus showed a drop in activity when a stimulus was spontaneously reported to disappear from view (despite being continuously present). A neighboring thalamic nucleus, the lateral geniculate nucleus, did not show such changes. This difference revealed that these two nuclei bear a different relationship to stimulus visibility. In the second component of this project, we explored the contributions of both the lateral geniculate nucleus and the pulvinar to visibility using a combination of targeted cortical ablation and reversible thalamic inactivation. One study investigated the basis of the phenomenon of blindsight, which refers to the unconscious vision that is known to follow lesions to the primary visual cortex of humans and monkeys. Despite the fact that patients with blindsight claim that they are unable to see anything in a certain region of visual space, careful testing shows that they can detect and even discriminate stimuli quite well in the blind visual field. The pathways serving this unconscious form of vision have been discussed and debated for several decades. In our nonhuman primate model, we focused on the thalamic portion of this pathway, as it is clear that any visual information reaching the cortex must be relayed through the thalamus. We found that inactivating the lateral geniculate nucleus obliterated blindsight. Prior to such inactivation, monkeys were able to respond to stimuli in a region of visual space corresponding to complete V1 ablation. However, following inactivation, this residual visual performance was abolished, leaving the monkeys completely blind. Our findings suggest that pathways passing through the lateral geniculate nucleus to the extrastriate visual cortex carry unconscious retinal information that can be used to guide visual behavior. We are presently following this study with an electrophysiological study of residual cortical activation. Understanding how and when the high-level visual cortex regains its responsiveness after ablation of the primate visual cortex is important for understanding residual vision during blindsight. It also serves as a model for studying plasticity in the brain more generally, where experience and training following injury can lead to the recruitment of new cortical areas. Together, bistable perception and blindsight represent paradigms for studying neural circuitry related to conscious and unconscious visual perception. We have recently written a comprehensive review on this topic, which is due to be published in 2012.

我们对周围世界的视觉看法是如此直接和直观，以至于大脑根本不需要解决任何问题。但是，超过50％的大脑皮层（大脑的突出外覆盖）专门用于观察。人类和其他灵长类动物比任何其他意义都更依赖于视觉，与环境互动以及彼此之间的互动。每次我们重定向凝视时，每秒发生多次事件时，视网膜受体都会面临着新的浅色，黑暗和颜色的模式。我们的大脑可以解码，解释和采取行动。正确解释视网膜信息的无能力是正确的基础是一系列严重的赤字。在频谱的一端，个体是盲目的，必须依靠其他感觉才能生存。另一方面，他们的基本视野是正常的，但是他们倾向于误判距离，或者误解了其他人的身份，情绪状态或意图。研究大脑解码和解释视网膜图像中固有的信息的基本机制对于理解人脑最令人印象深刻和最重要的功能至关重要。标题为视觉感知神经生理学的项目具有两个组成部分，每个组成部分都使用非人类灵长类动物模型来理解人类视觉感知的神经基础。我们结合了最现代的电生理记录，功能磁共振成像（fMRI）以及猴子中可逆的局部灭活，使我们能够隔离与视觉特定方面相关的和研究机制。第一个组件侧重于所谓的视觉线条，颜色，形状和动作的原始组件，以了解如何从基本的构件中组装出更复杂的看法。这是视觉大脑的第一个任务，其核心原理仍然知之甚少。从某种意义上说，视网膜上的所有信息都处于原始状态，因为模式激活了对不同颜色和位置敏感的光检测器。然后，大脑皮层提取较高的原语，例如方向，运动方向和轮廓形状，这是由那里的神经元反应的视觉刺激的类型所证明的。在某些情况下，可以在其感知解释中安排视觉原始图。当面对固有的模棱两可的刺激时，感知会在两个替代印象之间波动。也就是说，它变得可行。心理学教科书中著名的双重人物包括核心立方体和鲁宾斯面对花瓶刺激，尽管有数百个例子。在过去的几年中，我们训练了非人类灵长类动物，以报告每个时间点可见两种感知解释中的哪个。猴子通过将两个杠杆之一拉到灵长类动物主席中来报告此信息。基于这些行为反应，我们可以研究脑活动的哪些方面，其中皮质区域遵循猴子主观感知状态。请注意，这个问题偏离了更常规的研究，在该研究中，在刺激特征的函数中跟踪神经反应。在这种情况下，刺激总是相同的，但是猴子的感知会改变。最近，我们发现，视觉丘脑是大脑中间的大型继电器结构，与大脑皮层相互作用，显示了反映猴子感知状态的活性变化。更具体地说，当刺激自发地从视线中消失时（尽管不断存在）时，pulvinar核显示出活性下降。邻近的丘脑核，侧向基因核，没有显示出这种变化。这种差异表明，这两个核与刺激可见性具有不同的关系。在该项目的第二个组成部分中，我们使用靶向皮质消融和可逆的丘脑灭活的组合探讨了侧向元素核和pulvinar对可见性的贡献。一项研究调查了盲目现象的基础，该现象是指无意识的视力，该视力已知会遵循人类和猴子的主要视觉皮层。尽管盲目的患者声称他们无法在视觉空间的某个区域内看到任何东西，但仔细的测试表明，他们可以在盲目的视野中很好地检测甚至可以很好地区分刺激。几十年来，已经讨论了和辩论这种无意识形式的愿景形式的途径。在我们的非人类灵长类动物模型中，我们专注于该途径的丘脑部分，因为很明显，任何到达皮层的视觉信息都必须通过丘脑传递。我们发现，灭活横向遗传核的灭绝盲目的视线。在这种灭活之前，猴子能够在与完全V1消融的视觉空间区域中对刺激做出反应。然而，随后，这种残留的视觉表现被消除了，使猴子完全盲目。我们的发现表明，穿过侧向基因核向腹部视觉皮层的途径带有无意识的视网膜信息，可用于引导视觉行为。目前，我们正在遵循这项研究，对残留皮质激活的电生理研究。了解高水平的视觉皮层在消融灵长类动物视觉皮层后如何重新获得其反应性，这对于理解盲目期间的残留视力很重要。它也是更广泛地研究大脑可塑性的模型，在这种模型中，受伤后的经验和训练可以导致新的皮质区域招募。共同的感知和盲目的视觉代表了研究与有意识和无意识的视觉感知有关的神经回路的范式。我们最近对该主题撰写了全面的评论，该评论将于2012年发表。