Neural mechanisms mediating visual search

描述（由申请人提供）：我们必须经常在杂乱的场景中寻找与行为直接相关的物品-例如，我们的食物，我们的车钥匙，我们的孩子，等等。在每一种情况下，我们都使用我们对物体特征的记忆来有效地指导我们的搜索，这样我们就不会被迫在拥挤的场景中单独检查每一个物体。高效的视觉搜索至关重要 用于有效的视觉引导行为。虽然我们对关注位置的生物学机制了解很多，但对由物体特征引导的视觉搜索的机制却知之甚少。我们还不知道相关物体特征的信息存储在神经系统的什么地方，这些信息是如何用来引导眼球运动来检查那些适合搜索的物体的，或者特征信息是如何调节我们视觉皮层中处理的信息的。为了设计一个有效的神经假体或治疗注意力障碍的人，我们需要在系统层面上更好地理解视觉搜索中的特征注意力。更好地理解特征注意也可能让我们深入了解视觉工作记忆和视觉表象的机制，因为这些相关功能似乎至少涉及部分重叠的神经回路。在视觉搜索过程中，前额叶皮层和丘脑枕核可能在引导特征注意方面发挥作用。事实上，枕可能起到将关键特征信息从前额叶皮层传递到视觉皮层的作用。我们的目标是集中在这两个结构，我们的指导下，我们的初步数据，其功能。在目标1中，我们将在执行视觉搜索任务时同时记录前额叶皮层45区、额叶眼场（FEF）和视觉皮层V4区的神经元。这些记录将测试有关前额叶细胞如何影响FEF和V4区中对象特征信息的后续处理的假设。在目标2中，我们将使用新开发的光遗传学技术，在目标1中使用的相同的特征注意力测试过程中，测试有关前额叶皮层如何影响搜索过程中的行为以及FEF和V4神经元反应的因果假设。我们与合作者成功实施的光遗传学技术将使我们能够在精确的位置和精确的时间段内抑制神经回路。在目标3中，我们将在相同的特征注意测试中同时记录枕、V4区和下颞叶皮层。 我们将测试有关枕如何在特征注意过程中调节皮层处理的假设，包括其在皮层群体中同步和去同步活动中的作用。然后，我们将使用Aim 2中使用的相同光遗传学技术来测试我们的结论，以在执行任务期间的关键时刻抑制枕活动。总的来说，我们希望这些研究能给我们提供迄今为止最好的解释，说明在注意物体特征的过程中，多个大脑结构之间的相互作用如何导致有效的视觉处理。

DESCRIPTION (provided by applicant): We must often search cluttered scenes for items of immediate behavioral relevance - e.g. our food, our car keys, our child, and so on. In each case, we use our memory of the object's features to effectively guide our search, so that we are not forced to inspect every object in a crowded scene individually. Efficient visual search is critical for efficient visually guided behavior. Although much is known about the biological mechanisms that underlie the ability to attend to locations, very little is known about the mechanisms underlying visual search guided by object features. We do not yet understand where the information about the relevant object features is stored in the nervous system, how that information is used to guide eye movements to inspect object that are good candidates for the searched-for item, or how the feature information modulates the information processed in our visual cortex. To design an effective neural prosthesis or to treat people with attentional disorders, we need a better understanding of feature attention in visual search at the systems level. A better understanding of feature attention will likely also give us insight into the mechanisms underlying visual working memory and visual imagery, as these related functions seem to involve at least partially overlapping neural circuits. Two key structures that may play a role in the guidance of feature attention during visual search are the prefrontal cortex and the pulvinar nucleus of the thalamus. In fact, the pulvinar may serve to relay critical feature information from prefrontal cortex to visual cortex. Our Aims are focused on these two structures, and we are guided by our preliminary data regarding their functions. In Aim 1, we will simultaneously record from neurons in Area 45 of the prefrontal cortex, the frontal eye fields (FEF) and area V4 of visual cortex during performance of a visual search task. These recordings will test hypotheses about how prefrontal cells influence the subsequent processing of object feature information in FEF and area V4. In Aim 2, we will use newly developed optogenetic techniques during performance of the same tests of feature attention used in Aim 1, to test causal hypotheses about how the prefrontal cortex influences both behavior during search and the responses of FEF and V4 neurons. The optogenetic techniques we have successfully implemented with our collaborators will allow us to suppress neural circuits at precise locations and for precise periods of time. In Aim 3, we will record simultaneously from the pulvinar, area V4, and the inferior temporal cortex during the same tests of feature attention. We will test hypotheses about how the pulvinar regulates cortical processing during feature attention, including its role in synchronizing and de-synchronizing activity in cortical population. We will then test our conclusions using the same optogenetic techniques used in Aim 2, to suppress pulvinar activity at critical times during the performance of the tasks. In total, we expect these studies to give us the best account so far of how the interactions among multiple brain structures leads to effective visual processing during attention to object features.