The Neural Mechanisms Underlying the Guidance of Visual Attention

描述（由申请人提供）：我们研究视觉注意力，因为它在视觉感知中的重要性。行为范式，如变化盲视，已经向我们表明，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物体的信息。因为视觉注意力是视觉感知的基础，它是我们与感知世界的大多数互动的基础--包括我们的身体互动和 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-他们与世界互动的困难导致住院时间明显长于许多其他中风患者，为家庭成员和整个社区带来更大的成本。因此，增加我们对注意力引导机制的理解，不仅对我们更深入地了解大脑如何根据外部和认知输入做出决策至关重要，而且对我们深入了解视觉感知本身的机制也至关重要。在之前的资助中，我们专注于外侧顶内区（LIP）的作用，并展示了LIP的活动如何用于引导注意力。该研究的结果表明，LIP中的信息需要以特定的方式进行处理，然后才能用于指导眼球运动。在这项研究中，我们建立在这项工作的基础上，通过测试预测的假设，有一个互惠的连接，从额叶眼场（FEF）到LIP，其中一个子集的神经元在FEF提供自上而下的输入LIP和一个子集的神经元在FEF接收处理信息从LIP。我们通过检查FEF中神经元的反应并将它们识别为投射到LIP或接收来自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，这些信号可能是LIP中所见的自上而下反应的起源。我们将表明，神经元直接或间接的项目回到LIP的早期反应，其中包含组件信号，是足够的，适当的解释自上而下的影响LIP。这些响应通常在眼睛运动之前开始，并且通常在眼睛停止运动之后150-200 ms被前馈连接覆盖。在目标2中，我们测试了FEF神经元中的后期响应与LIP中所见的响应的归一化输出一致的预测。我们通过比较FEF中的反应与行为和刺激值的估计来做到这一点。基于在早期皮层区域观察到的反应，我们对接收这些信息的神经元应该如何行为有了明确的预测。总的来说，这些实验旨在展示LIP-FEF回路如何引导注意力的分配，并且这样做将使我们更好地理解神经回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.