Interaction of Visual and Oculomotor Signals in Cortex

描述(申请人提供)：视觉的一个基本事实是，我们对外部世界的感知是由许多行为和背景因素塑造的。这些因素包括视觉选择性注意，在视觉选择性注意中，感官信息被过滤，倾向于 在行为和背景上都是相关的。它还包括通过广泛投射的神经调节系统来调节感觉信号，它还包括在每秒发生几次眼跳运动期间对视觉处理的调节。目前的建议侧重于解决关键的、互补的问题，即影响灵长类大脑内视觉处理的这些基本因素背后的神经机制。到目前为止，已有证据表明，参与凝视控制的大脑结构，如前额叶皮质的额叶眼场(FEF)，因果地参与了后部视觉皮质内视觉信号的调制，并且这些结构在上述感觉调制的每一种形式中都发挥了作用。在第一个目标中，我们将测试空间注意和注意调制对FEF的依赖性，并确定FEF反馈投射到视觉皮质的功能特性。虽然FEF在视觉空间注意和视皮层注意的相关性中起因果作用已经变得很清楚，但这一证据并不完整。特别是，尚不清楚伴随着选择性视觉注意的后部视觉皮层内活动的调节实际上是否依赖于FEF。我们将通过测试FEF局部失活对视觉空间注意的影响来解决这个关键问题 使用多电极、层流记录，在猴子的V4区内与其相应的神经联系。此外，我们还将确定直接投射到V4区的FEF神经元的功能类别。在第二个目标中，我们将确定儿茶酚胺对FEF的空间注意控制和注意调节的影响。在啮齿动物和灵长类动物身上进行的研究表明，去甲肾上腺素和多巴胺都在注意力和工作记忆等认知功能的前额叶控制中发挥作用。我们将确定或排除这些神经调节剂在控制视觉选择性注意中的作用，并相应地通过FEF调节注意期间的视觉皮质活动。在这一目标中，我们将识别视觉加工中视交叉前改变的神经关联，并探索其来源。眼球跳动会导致视网膜图像频繁而实质性的移位，但它们却没有被注意到。视觉和眼球运动系统如何应对视觉图像频繁中断的基本问题仍然没有解决，但有证据表明，在视觉系统的某些阶段，就在眼跳开始之前，视觉表征存在着强烈的变化。我们将测量FEF和区域嘴唇神经元的视觉感受野的动力学，我们将测试FEF和LIP中的神经元是否表现出扫视抑制，我们将检验视觉皮质对比敏感度的扫视抑制至少部分由FEF驱动的假设。总体而言，我们的重点是更多 影响视觉处理的重要因素，再加上我们使用的最先进的神经生理学方法和因果方法，很可能会对我们对视觉感知的神经机制的理解产生巨大而持久的影响。

DESCRIPTION (provided by applicant): A fundamental fact of vision is that our perception of the external world is shaped by a number of behavioral and contextual factors. These factors include visual selective attention, in which sensory information is filtered in favor of items that are behaviorally and contextually relevant. It also includes the modulation of sensory signals by diffusely projecting neuromodulatory systems, and it includes the modulation of visual processing during saccadic eye movements which occur several times each second. The current proposal focuses on addressing key, complementary questions about the neural mechanisms underlying these basic factors that influence visual processing within the primate brain. Evidence to date has established that brain structures involved in gaze control, such as the frontal eye field (FEF) in prefrontal cortex (PFC), are causally involved in modulating visual signals within posterior visual cortex, and that such structures play a role in each of the above forms of sensory modulation. In the first aim, we will test the dependence of spatial attention and attentional modulation on the FEF, and identify the functional properties of FEF feedback projections to visual cortex. Although it has become clear that the FEF plays a causal role in visual spatial attention and the correlates of attention in visual cortex, this evidence is incomplete. In particular, it is not known if the modulation of activity within posterior visual cotex that accompanies selective visual attention actually depends on the FEF. We will address this crucial question by testing the impact of local inactivation of the FEF on visual spatial attention and its corresponding neural correlates within area V4 of monkeys using multi- electrode, laminar recordings. In addition, we will determine the functional class(es) of FEF neurons that project directly to area V4. In the second aim, we will determine the influence of catecholamines on the control of spatial attention and attentional modulation by the FEF. Studies conducted in rodents and primates suggest that both noradrenaline and dopamine play a role in the prefrontal control of cognitive functions such as attention and working memory. We will establish, or rule out, a role of these neuromodulators in the control of visual selective attention, and correspondingly the modulation of visual cortical activity during attention, by the FEF. In the thid aim, we will identify neural correlates of presaccadic changes in visual processing and probe their source. Saccadic eye movements lead to frequent and substantial displacements of the retinal image, yet they go unnoticed. The basic question of how the visual and oculomotor systems combat the problem of frequent disruptions in the visual image remains unsolved, but evidence suggests the existence of robust changes in visual representations at some stages in the visual system just prior to saccade onset. We will measure the dynamics of visual receptive fields of FEF and area LIP neurons, we will test whether neurons in the FEF and LIP exhibit saccadic suppression, and we will test the hypothesis that saccadic suppression of visual cortical contrast sensitivity is driven at least in part by the FEF. Overall, our focus on the more significant factors affecting visual processing, combined with our use of state-of-the-art neurophysiological approaches and causal methods, are likely to produce results that exert a large and sustained impact on our understanding of the neural mechanisms of visual perception.