Elucidating the role of the oculomotor circuit in free viewing visual search

项目摘要 近50年来，科学家们一直在研究眼球运动控制和活动之间的关系。 对额眼野（FEF）、上级丘（SC）和外侧顶内区（LIP）神经元的活动进行了观察。总 这些研究的发现是所有三个区域中的神经元对于眼球运动行为都是重要的， 但他们发现这些区域之间几乎没有什么区别，这意味着它们都做类似的事情。最近， 少数实验室已经开始使用更自然的自由观看行为任务， 这些区域的神经反应存在许多实质性差异，表明它们各自发挥着重要作用。 独特的角色。基于这些数据，我们对每个区域的作用以及它们如何可能 作为一个网络来产生行为。简而言之，我们已经提出LIP充当简单的优先级映射， FEF活动控制扫视的时间，SC活动代表最终决定 去哪里找此外，FEF中的一个神经元子集记录了动物看过的地方。建筑 在这项先前的工作基础上，目前的建议有两个主要目标。首先是填补我们知识上的两个空白 这对我们的假设至关重要作为这一目标的一部分，我们建议从SC神经元记录在一个 自由观察视觉觅食任务，以确认SC活动不受刺激身份在正在进行的搜索。 我们还建议以更自然的方式记录FEF神经元，以确保 我们以前在维持注视期间看到的抑制是控制眼睛时间的机制。 运动，而不是一个机制有关的回报预期。这些研究的结果将完善 我们的假设，并设置我们的建议的第二个主要目的，这是为了测试我们的假设是否 角色在功能上有效。第二个目标分为三个部分。在每一个，我们将因果测试方面 我们的假设。在第一个实验中，我们将在不同的时间微刺激LIP，以测试是否 我们在FEF中识别的抑制控制来自LIP的信息流以引导扫视。在第二 实验中，我们将从FEF和SC记录LIP。这个实验的结果将测试 假设LIP活动通过FEF和SC驱动扫视行为，如果不是，这些记录应该 确定哪些区域确实在指导行为方面发挥作用。在第三个实验中，我们将在 这将使我们能够测试我们假设的三个额外方面：FEF活动是否 指导行为以及这是否也在SCI中表示; FEF中的跟踪信号是否在功能上 相关;以及FEF中的活动是否参与控制扫视的时间流。这些结果 将解决一个长达数十年的问题，为什么我们有多个大脑区域，通过提供一个明确的指示， LIP、FEF和SC的作用是在日常视觉行为中。考虑到广泛的患者， 神经系统疾病有异常的眼球运动行为，这些结果可能有助于发展 药理学或行为学方法来对抗这些问题。

Project Summary For almost 50 years, scientists have investigated the relationship between eye movement control and the activity of neurons in the frontal eye field (FEF), superior colliculus (SC) and lateral intraparietal area (LIP). The general findings of these studies have been that neurons in all three areas are important for eye movement behavior, but they have identified very few differences between the areas, implying that they all do similar things. Recently, a small number of labs have started using more naturalistic free-viewing behavioral tasks and have found a number of substantive differences in neural responses across these areas, suggesting that they each play a unique role. Based on these data, we formed a hypothesis about the roles of each area and how they may function as a network to generate behavior. Briefly, we have proposed that LIP acts as simple priority map that is constantly accessible, FEF activity controls the timing of saccades and SC activity represents the final decision about where to look. In addition, a subset of neurons in FEF keeps track of where the animal has looked. Building on this previous work, the current proposal has two main aims. The first is to fill in two gaps of our knowledge that are essential in finalizing our hypothesis. As part of this aim, we propose to record from SC neurons in a free viewing visual foraging task to confirm that SC activity is not affected by stimulus identity in ongoing search. We also propose to record from FEF neurons in an even more natural version of our task to make sure that suppression we have previously seen during maintained fixation is a mechanism for controlling the timing of eye movements as opposed to a mechanism related to reward expectation. The results of these studies will refine our hypothesis and set us up for the second main aim of the proposal, which is to test whether our hypothesized roles are functionally valid. This second aim is broken into 3 components. In each, we will causally test aspects of our hypothesis. In the first experiment, we will microstimulate LIP at different times to test whether the suppression we have identified in FEF controls the flow of information from LIP to guide saccades. In the second experiment, we will inactivate LIP while recording from FEF and SC. The results of this experiment will test the hypothesis that LIP activity drives saccadic behavior via FEF and SC and, if it does not, these recordings should identify which area does play a role in guiding behavior. In the third experiment, we will inactivate FEF while recording from SC. This will allow us to test three additional aspects of our hypothesis: whether FEF activity guides behavior and whether this is also represented in SCI; whether the tracking signal in FEF in functionally relevant; and whether the activity in FEF is involved in controlling the temporal flow of saccades. These results will solve a decades-long question of why we have multiple brain areas by providing a clear indication of what the roles of LIP, FEF and SC are in everyday visual behavior. Given that patients across a broad spectrum of neurological diseases have abnormal eye movement behavior, these results may aid in the development of pharmacological or behavioral methods to combat these problems.