Linking Neural Population Activity and Visual Perception

描述（由申请人提供）：拟议研究的总体目标是对灵长类动物初级视觉皮层（V1）的神经活动与视觉检测和识别任务中的行为表现之间的联系提供定量理解。为了实现这一目标，猴子被训练来执行四种苛刻的视觉检测和区分任务，使用小的定向视觉刺激，这些视觉刺激可以单独出现，也可以出现在视觉面具上。当猴子执行这些任务时，我们使用电压敏感染料光学成像结合电生理学来监测V1神经群的活动。然后，我们使用计算技术来研究视觉刺激、在多个空间尺度上测量的神经反应和观察到的对这些刺激的行为反应之间的关系。我们的前两个目标侧重于这三个变量之间的两个基本因果关系。在Aim #1中，我们的目标是确定V1神经元群体如何表示或编码关于目标和掩模的视觉信息。我们解决了三个主要问题：(i)在多个空间尺度上V1响应提供给其余视觉系统的信号质量如何，（ii）这些信息在V1中是如何分布的，以及（iii）从V1中提取这些信息的最佳方法是什么？为了形成关于目标的决定，V1之后的神经回路必须“读出”或解码V1神经元群提供的神经信号。我们在目标2中的目标是确定V1中的哪些神经元对目标的感知决策有贡献，以及它们的信号是如何汇集在一起形成这个决策的。最后，这两个基本关系——V1神经元对视觉信息的编码，以及V1反应在后续处理阶段的解码——可能会根据行为任务而改变。在Aim #3中，我们通过调节目标不确定性和目标相关性来改变任务。然后，我们研究了自上而下的机制是否以及如何根据任务的要求改变V1中目标的表示。总之，这项研究将极大地扩展我们对灵长类动物皮层中神经元群体表达和处理信息的方式的理解。

DESCRIPTION (provided by applicant): The overall goal of the proposed research is to provide a quantitative understanding of the link between neural activity in the primate primary visual cortex (V1) and behavioral performance in visual detection and discrimination tasks. To achieve this goal, monkeys are trained to perform four demanding visual detection and discrimination tasks using small oriented visual stimuli that could appear in isolation or on top of a visual mask. While the monkey performs these tasks, we use voltage-sensitive dye optical imaging in conjunction with electrophysiology, to monitor neural population activity in V1. We then use computational techniques to study the relationships between the visual stimuli, the measured neural responses at multiple spatial scales, and the observed behavioral responses to these stimuli. Our first two aims focus on two fundamental causal relationships between these three variables. In Aim #1 our goal is to determine how visual information regarding the target and the mask is represented, or encoded, by populations of V1 neurons. We address three primary questions: (i) what is the quality of the signals that are provided to the rest of the visual system by V1 responses at multiple spatial scales, (ii) how is this information distributed in V1, and (iii) what is the optimal way to extract this information from V1? To form a decision regarding the target, neural circuits subsequent to V1 must 'read out', or decode, the neural signals provided by populations of V1 neurons. Our goal in Aim #2 is to determine which neurons in V1 contribute to the perceptual decision regarding the target, and how their signals might be pooled to form this decision. Finally, these two fundamental relationships - the encoding of visual information by V1 neurons, and the decoding of V1 responses by subsequent processing stages - may change, depending on the behavioral task. In Aim #3, we vary the task by modulating target uncertainty and target relevance. We then examine if and how top-down mechanisms change the representation of the target in V1 based on the demands of the task. Together, this research will significantly expand our understanding of the way in which information is represented and processed by populations of neurons in the primate cortex. PUBLIC HEALTH RELEVANCE: Our ability to perceive, recognize, and act upon objects in our environment is mediated by neural circuits in the cerebral cortex. Our long-term goal is to understand how neural circuits in the cerebral cortex represent and process visual information. By addressing this goal, our research will help to elucidate the normal function of the cerebral cortex and its malfunction in neurological and neuropsychiatric disease.