Neural Mechanisms of Fixation Choice while Searching Natural Scenes

描述（由申请人提供）：这些实验的总体目标是了解大脑如何控制我们看的地方。要做到这一点，重要的是要在非常接近真实的世界的条件下研究大脑活动和行为。所有我们打算做的实验都将使用清醒的恒河猴作为实验对象。在之前的工作中，我们研究了猴子在观看自然场景图像时大脑皮层额叶眼区的活动。额叶眼场（FEF）与目的性随意眼动的控制密切相关。当猴子寻找隐藏在自然场景图像中的目标时，FEF神经元的活动包括与规划即将到来的眼球运动相关的活动以及对图像的显著视觉特征敏感的活动。在我们对大脑如何控制眼球运动的理解不断发展的同时，我们对引导人类和猴子眼球运动的自然图像特征的理解也取得了实质性的进展。这些行为研究处于能够准确预测眼球运动模式的先进水平。我们的目标是利用这些进步来预测自然环境中的眼球运动模式，以帮助我们了解导致这种行为的大脑活动。我们将集中在FEF的神经元活动，由于其在随意眼球运动的控制中的重要作用。该提案有3个目标，每个目标都集中在一个不同的因素，已知在自然条件下引导眼球运动。显著性描述了视觉场景的一小部分与场景的其余部分基于刺激特征（如颜色，对比度，形状和方向）的不同程度。我们的第一个目标将确定的影响，突出后FEF活动。在我们的第二个目标中，我们将量化相关性的影响。相关性是指视觉特征对手头任务的重要性;例如，如果我们正在寻找红色目标，图像中的红色项目将更有可能吸引我们的注意力，并最终成为眼球运动的目标。了解场景的大致构成，即所谓的场景要点，可以告诉我们物体更有可能被发现的地方。例如，如果我们正在寻找一辆自行车，我们更倾向于搜索街道场景的人行道和道路，而忽略其他不太可能找到自行车的地方。我们的最终目标是寻找场景主旨对猴子行为的影响，以及FEF活动驱动这种行为。除了上面概述的大脑记录实验之外，我们的大部分工作将致力于对我们获得的行为和神经元数据进行数学分析和建模。我们的最终目标是提供一个模型，预测的贡献的显着性，相关性，和主旨的FEF神经元的活动。成功的模型将是一个数学表示，预测搜索相关的活动在FEF为人工和真实的世界条件。 公共卫生相关性：由于猴子和人类的眼动系统之间的已知和预期的相似性，这些实验提供了一个模型，在人类的额叶眼场皮层的功能组织。做出适当的眼球运动的能力是一种可以被许多疾病破坏的功能，包括脑中风、阿尔茨海默氏症、帕金森氏症和精神分裂症。更具体地说，在搜索复杂视觉刺激期间，在患有失认症的患者以及诊断为自闭症谱系障碍的个体中描述了对注视的适当控制的缺陷。

DESCRIPTION (provided by applicant): The overall goal of these experiments is to understand how the brain controls where we look. To accomplish this, it is important to study brain activity and behavior under conditions that closely approximate those in the real world. All of the experiments we propose to do will use awake behaving rhesus monkeys as subjects. In prior work, we have studied activity in the cortical frontal eye field while monkeys looked at images of natural scenes. The frontal eye field (FEF) is closely involved in the control of purposive voluntary eye movements. While the monkey searched for a target hidden in the images of natural scenes, the activity of FEF neurons consisted of combinations of activity related to planning upcoming eye movements, as well as activity that was sensitive to salient visual features of the image. In parallel with the development of our understanding of how the brain controls eye movements, there have been substantial advances in our understanding of the features of natural images that guide both human and monkey eye movements. These behavioral studies are at the advanced level of being able to accurately predict patterns of eye movements. Our goal in this proposal is to take advantage of these advancements in predicting patterns of eye movements in natural environments to help us understand the brain events that are responsible for this behavior. We will focus upon neuron activity in the FEF due to its essential role in the control of voluntary eye movements. The proposal has 3 Aims each focused upon a different factor that is known to guide eye movements under natural conditions. Salience describes how different a small part of a visual scene is from the remainder of the scene based upon stimulus features such as color, contrast, shape, and orientation. Our first aim will define the effects that salience has upon FEF activity. In our second aim, we'll quantify the effects of relevance. Relevance refers to the importance of visual features for the task at hand; for example, if we're looking for a red target, the red items in the image will be more likely to attrat our attention and ultimately be the target for an eye movement. Knowing the broad composition of a scene, a quality that is called scene gist, can tell us the places where an object is more likely to be found. For example, if we are looking for a bicycle, we are more likely to search the sidewalks and roadways of a street scene and ignore other places where bicycles are unlikely to be found. Our final aim will look for the effects of scene gist upon monkey behavior and the FEF activity driving that behavior. In addition to the brain recording experiments outlined above, a large part of our effort will be devoted to mathematical analysis and modeling of the behavioral and neuronal data we obtain. Our ultimate goal is to provide a model that predicts the contributions of salience, relevance, and gist to the activity of FEF neurons. The successful model will be a mathematical representation that predicts search-related activity in the FEF for both artificial and real world conditions. PUBLIC HEALTH RELEVANCE: Due to the known and expected similarities between monkey and human eye movement systems, these experiments provide a model for the functional organization of frontal eye field cortex in humans. The ability to make appropriate eye movements is a function that can be damaged by a number of diseases, including cerebral stroke, Alzheimer's, Parkinson's, and Schizophrenia. More specifically, deficits in the proper control of fixation during search of complex visual stimuli have been described in patients suffering from simultanagnosia, as well as in individuals with a diagnosis of autism spectrum disorder.