Dynamic mechanisms of active vision in prefrontal cortex

描述（由申请人提供）：在自然条件下，当我们扫描丰富的视觉环境时，我们的视觉体验的特征是频繁的眼球运动。然而，大多数实验都集中在视觉和行为贫乏条件下的神经反应上，牺牲了现实条件来获得可驾驭性。越来越多的人认识到，在这些条件下的大脑活动并不总能推广到更自然的环境中，因此需要在更复杂的情况下进行探索神经元动力学的实验。该应用程序的长期目标是确定灵长类动物大脑中的神经回路如何在频繁眼球运动和内部认知状态变化的情况下产生连贯的视觉感知。额叶视野（FEF）是前额叶皮层中控制眼球跳动的关键部分，由于其在皮层结构中的独特地位，在这一功能中起着关键作用。FEF神经元具有视觉和运动功能，与控制眼睛的皮层下结构和视觉皮层区域有联系。FEF神经元是如何在这个通道中发挥作用的，它具有整合视觉信息以指导眼球运动和将计划的运动命令告知视觉系统的双重功能？一条线索来自对预测性重新映射现象的研究，在这种现象中，神经元在即将到来的扫视之前改变了它们的空间偏好。这发生在FEF神经元以及其他皮层区域，并暗示其反应特性的频繁和动态变化。运动规划会带来什么样的动态变化？产生这些动态所需的信息是如何通过神经元回路传播的？我们将在三个具体目标中解决这些问题，第一个目标是使用快速呈现的稀疏噪声刺激（一种在早期视觉区域开发的方法）来探测FEF神经元反应的动态。我们假设FEF神经元具有精确的时间动态，能够对快速闪过的刺激做出反应，以及非线性空间求和，从而导致对被视为潜在扫视目标的小刺激产生强烈反应。第二个具体目标是使用相同的噪声刺激测量具有高空间和时间精度的预测性重映射响应。我们假设，重新映射表现为在跳周时间内接受野的逐渐转移，这发生在引导扫视和更自然的自发扫视中。在第三个具体目标中，我们试图通过同时记录FEF神经元群来分离负责这些动态变化的神经元回路。我们假设在眼球运动之前，FEF内部的局部电路被调用来在神经元之间传递信息。本研究的总体结果将是确定FEF在主动视觉过程中整合视觉感知和运动控制的作用，并构建一个使用感受野映射和种群记录来测量视觉和运动系统神经回路动态变化的框架。这将有助于开发视觉神经障碍的治疗方法和脑外伤后的康复

DESCRIPTION (provided by applicant): Under natural conditions, our visual experience is characterized by frequent eye movements as we scan a rich visual environment. Most experiments, however, have focused on neural responses under visually and behaviorally impoverished conditions, sacrificing realistic conditions for tractability. There is a growing realization that the brain's activity under these conditions does not always generalize to more natural settings, and experiments that probe neuronal dynamics under more complicated situations are needed. The long-term goal of this application is to determine how neural circuits in the primate brain act to generate coherent visual perception despite frequent eye movements and changes in internal cognitive state. The frontal eye field (FEF), a part of prefrontal cortex critical for controlling saccadic eye movements, plays a key role in this function through its unique position in the cortical hierarchy. FEF neurons serve both visual and motor functions, with connections to subcortical structures that control the eyes and to visual cortical areas. How do FEF neurons act in this gateway, serving the dual functions of integrating visual information to guide eye movements and informing the visual system about planned motor commands? One clue comes from studies of the phenomenon of predictive remapping, in which neurons shift their spatial preferences prior to an impending saccade. This occurs in FEF neurons as well as other cortical areas, and hints at the frequent and dynamic changes in their response properties. What kinds of dynamic changes are brought on by motor planning? How does the information necessary to generate these dynamics propagate through neuronal circuits? We will address these questions in three specific aims, the first of which uses rapidly presented sparse noise stimuli, an approach developed in early visual areas, to probe the dynamics of FEF neuronal responses. We hypothesize that FEF neurons have precise temporal dynamics, enabling responses to rapidly flashed stimuli, and nonlinear spatial summation, leading to strong responses to small stimuli that are perceived as potential saccade targets. The second specific aim is to measure the predictively remapped response with high spatial and temporal precision using the same noise stimulus. We hypothesize that remapping manifests as a gradual shift in the receptive field in the peri-saccadic time period, and this occurs for both guided saccades and more naturalistic spontaneous saccades. In the third specific aim, we attempt to isolate the neuronal circuitry responsible for these dynamic changes by recording simultaneously from a population of FEF neurons. We hypothesize that local circuitry within FEF is invoked to transfer information between neurons prior to an eye movement. The overall result of this study will be to establish the role of FEF in integrating visual perception and motor control during active vision, and to construct a framework for using receptive field mapping and population recordings to measure dynamic changes in neural circuits across visual and motor systems. This will aid in developing treatments for neurological disorders of vision and rehabilitation after traumatic brain injury or disease.