Linking Neural Population Activity and Visual Perception

描述(申请人提供)：感觉神经科学的一个中心目标是了解感觉皮质区域的神经编码，从而通过监测参与知觉任务的受试者的神经反应，可以实时地阅读神经表示的内容，并解释受试者的感知能力。这项拟议研究的首要目标是了解灵长类V1中神经编码的性质。具体地说，我们将集中在两个重要的感知任务中的神经编码，模式识别和轮廓分组。在目标1中，我们将检验假设，此外 对于通过一小部分高选择性神经元的活动来表示刺激，V1表示依赖于整个视网膜定位图上神经群体反应的大规模空间变化模式。具体地说，我们最近在V1中发现了一个新的地形图信号，它反映了V1‘S视网膜图中刺激的亮度调制(LM)的空间表示。我们还记录了一个类似的视网膜定位信号，反映了刺激对比度调制(CM)的整体模式。通过监测猴子执行阈值方位辨别任务时视网膜和柱状细胞尺度上的神经反应，我们将检验视网膜原位LM和CM信号有助于视觉感知的假设。在目标2中，我们将研究灵长类V1对知觉分组的贡献--将属于同一对象的不同视觉元素分组在一起的过程。具体地说，我们将测试这一假设，即涉及V1中特定于配置的横向相互作用的机制在这一过程中发挥关键作用，并通过将可能属于同一对象的一对元素链接在一起来启动分组。为了验证这一假设，我们将监测猴子在执行一项具有挑战性的自然主义知觉分组任务时V1中的神经种群反应。此外，这些实验将被用来确定对局部图像元素的反应结合在一起形成灵长类V1种群活动的时空模式的规则。总体而言，拟议的实验可能会为调节皮质感觉处理的神经机制提供重要而独特的见解。

DESCRIPTION (provided by applicant): A central goal of sensory neuroscience is to understand the neural code in sensory cortical areas to the point where, by monitoring neural responses in a subject engaged in a perceptual task, one could "read", in real time, the content of the neural representation and account for the subject's perceptual capabilities. The overarching goal of the proposed research is to understand the nature of the neural code in primate V1. Specifically, we will focus on the neural code in two important perceptual tasks, pattern discrimination and contour grouping. In Aim 1 we will test the hypothesis that, in addition to representing stimuli by the activity of a small subset of highly selective neurons, V1 representation relies on the large-scale pattern of spatial variations in neural population responses across the retinotopic map. Specifically, we recently discovered a novel topographic signal in V1, reflecting the spatial representation of the stimulus's luminance modulations (LM) in V1's retinotopic map. We also documented a similar retinotopic signal reflecting the global pattern of the stimulus' contrast modulations (CM). By monitoring neural responses at the retinotopic and columnar scales as monkeys perform a threshold orientation discrimination task, we will test the hypothesis that the retinotopic LM and CM signals contribute to visual perception. In Aim 2 we will examine the contribution of primate V1 to perceptual grouping - the process of grouping together disparate visual elements that belong to the same object. Specifically, we will test the hypothesis that mechanisms involving configuration-specific lateral interactions in V1 play a key role in this process, and initiate the grouping by linking together pairs of elements that are likely to belong to the same object. To test this hypothesis, we will monitor neural population responses in V1 of monkeys as they perform a challenging and naturalistic perceptual grouping task. In addition, these experiments will be used to determine the rules by which responses to local image elements combine to form a spatiotemporal pattern of population activity in primate V1. Overall, the proposed experiments are likely to provide important and unique insights into the neural mechanisms that mediate cortical sensory processing.