Neural mechanisms mediating visual search

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、汽车 钥匙，我们的孩子，等等。在每一种情况下，我们都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单独检查拥挤场景中的每个对象。高效视觉 搜索对于有效的视觉引导行为至关重要。尽管我们对生物学的了解很多， 的机制，基础上的能力，参加的位置，很少有人知道的机制 由物体特征引导的潜在视觉搜索。我们还不知道在哪里的信息， 相关的物体特征被储存在神经系统中，这些信息如何被用来引导眼球运动 来检查是搜索项的良好候选对象的对象，或者特征信息如何调制 信息在我们的视觉皮层中被处理。设计一个有效的神经假体或者治疗患有 注意障碍，我们需要更好地了解视觉搜索中的特征注意在系统水平。 更好地理解特征注意力也可能使我们深入了解视觉的潜在机制。 工作记忆和视觉意象，因为这些相关的功能似乎涉及至少部分重叠 神经回路两个关键结构，可能发挥作用，在指导功能的注意，在视觉 搜索的是前额叶皮层和丘脑的枕核。事实上，枕垫可能有助于 将关键特征信息从前额叶皮层传递到视觉皮层。我们的目标集中在这两个 结构，并且我们以关于其功能的初步数据为指导。在目标1中，我们 同时记录前额叶皮层45区、额叶眼区（FEF）和V4区的神经元 在执行视觉搜索任务时的视觉皮层。这些录音将测试关于 前额叶细胞影响FEF和V4区物体特征信息的后续加工。在Aim中 2，我们将在进行相同的特征测试期间使用新开发的光遗传学技术， 目标1中使用的注意力，以检验有关前额叶皮层如何影响两种行为的因果假设 以及FEF和V4神经元的反应。我们已经成功的光遗传学技术 与我们的合作者一起实现的技术将使我们能够在精确的位置抑制神经回路， 一段时间。在目标3中，我们将同时记录枕、V4区和下颞叶 在同样的特征注意力测试中。我们将测试关于枕如何调节 特征注意过程中的皮层处理，包括其在同步和去同步活动中的作用， 皮质种群然后，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， 在执行任务的关键时刻抑制枕的活动。总的来说，我们预计这些 这些研究给了我们迄今为止最好的解释，说明了多种大脑结构之间的相互作用是如何导致 有效的视觉处理过程中注意对象的特点。!

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 populations. 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. !