The Neural Mechanisms Underlying the Guidance of Visual Attention

描述(申请人提供)：我们研究视觉注意，因为它在视觉感知中的重要性。行为范式，如改变失明，已经告诉我们，虽然我们认为我们感知到了整个视觉世界，但我们只带走了我们所关注的区域或对象的信息。因为视觉注意力是视觉感知的基础，它构成了我们与感知世界的大多数互动的基础--包括我们的物理互动和 更多的智力互动，如学习和记忆。这一点在顶叶病变患者中尤为突出--他们在与世界互动方面的困难导致了比许多其他中风患者更长的住院时间，给家庭成员和整个社区带来了更大的成本。因此，除了让S更深入地了解大脑如何根据外部和认知输入做出决定，从长远来看，洞察视觉感知本身的机制，增加我们对注意力引导潜在机制的理解也是重要的，这是一个健康问题。在上一篇论文中，我们重点介绍了外侧顶内区(LIP)的作用，并展示了LIP中的活动如何用于引导注意力。这项研究的结果表明，嘴唇中的信息需要以特定的方式进行处理，才能用来指导眼睛的运动。在这项研究中，我们通过测试基于以下假设的预测：从额叶眼场(FEF)到LIP存在相互连接，其中FEF中的神经元子集提供自上而下的输入到LIP，FEF中的神经元子集从LIP接收处理的信息。我们通过检查FEF中神经元的反应并识别它们是投射到LIP还是接受LIP的投射来做到这一点。在目标1中，我们测试了FEF神经元编码信号的预测，这可能是LIP中看到的自上而下反应的起源。我们将展示直接或间接投射回LIP的神经元具有早期反应，其中包含足以和适当解释LIP自上而下效应的分量信号。这些反应通常在眼球运动之前开始，并经常在眼球停止运动150-200ms后被前馈连接所覆盖。在目标2中，我们测试了FEF神经元的后期反应与LIP中看到的反应的归一化输出一致的预测。我们通过将FEF中的反应与行为和刺激值的估计进行比较来做到这一点。根据在早期大脑皮层区域看到的反应，我们对接收到这些信息的神经元的行为有了明确的预测。总体而言，这些实验的目的是展示LIP-FEF电路如何引导注意力的分配，并通过这样做，让我们更好地理解神经电路如何在一般感觉-运动转换中处理信息。

DESCRIPTION (provided by applicant): We study visual attention because of its importance in visual perception. Behavioral paradigms, such as change blindness, have shown us that while we think we perceive the whole visual world, we only take away information about regions or objects that we have attended. Because visual attention is a foundation of visual perception, it underlies most of our interactions with the perceived world - both our physical interactions and more intellectual interactions, such as learning and memory. This is highlighted in patients with parietal lesions - the difficulty they have in interacting with the world leads to significantly loger hospital stays than many other stroke patients, incurring greater costs for family members and the community as a whole. Thus, increasing our understanding of the mechanisms underlying the guidance of attention is important as a health issue in addition to being critical in allowing s to gain a deeper insight into how the brain makes decisions based on both external and cognitive inputs and, in the long run, insight into the mechanisms underlying visual perception itself. In the previous grant, we focused on the role of the lateral intraparietal area (LIP), and showed how the activity in LIP can be used to guide attention. The results from that study suggested that the information in LIP needs to be processed in a specific way before it can be used to guide eye movements. In this study, we build on this work by testing predictions based on the hypothesis that that there is a reciprocal connection from the frontal eye field (FEF) to LIP, in which a subset of neurons in FEF provides top-down input to LIP and a subset of neurons in FEF receives processed information from LIP. We do so by examining the responses of neurons in FEF and identifying them as projecting to LIP or receiving projections from LIP. In aim 1, we test the prediction that FEF neurons encode signals which could be the genesis of top-down responses seen in LIP. We will show that neurons that project directly or indirectly back to LIP have early responses which contain component signals that are adequate and appropriate to explain top-down effects in LIP. These responses often begin before an eye movement is made and are often overridden by a feed-forward connection 150-200 ms after the eye stops moving. In aim 2, we test the prediction that later responses in FEF neurons are consistent with the normalized output of responses seen in LIP. We do this by comparing the responses in FEF to the behavior and estimates of stimulus value. Based on the responses seen in earlier cortical areas, we have explicit predictions about how neurons that receive this information should behave. Overall, these experiments are aimed at showing how the LIP-FEF circuit guides the allocation of attention and, in doing so, will give us a greater understanding o how neural circuits process information in general sensori-motor transformations.