Neural processing in covert attention

项目摘要 几个世纪以来，魔术师和魔术师都知道，如果他们分散了你的视线和注意力，你就不太可能 注意到他们的所作所为是显而易见的。这种疏忽失明是我们能力有限的结果。 了解视觉场景的一切，传统上是在实验室中通过视觉中的设定大小效果进行说明 搜索：你要搜索的物品越多，找到你想要的东西就越难，时间也就越长 这是需要的。我们最近发现，这种限制似乎并不涉及视觉区域的视觉处理， 而是在视觉信息向上传递到关联皮质时发生。我们假设会造成分裂 顶后皮质外侧顶内区(LIP)的正常化在这一过程中起着关键作用。 我们的假说结合了注意力、分裂归一化和决策的神经生理学知识 以解释与集合大小变化相关的行为影响。具体地说，我们建议 当寻找物品时，嘴唇的活动代表着从视觉区域积累的证据 物品在神经元的响应场中，如果活动在最后期限之前达到阈值，动物 指示项目位于该位置。这种积累受到分裂归一化的影响：条目越多 在视觉世界中，整个区域的活动越多，归一化程度越大，导致较低的 累积率。我们知道视觉注意可以增强视觉区域的反应，并提出这一点 LIP输入中的有效增益增加有助于覆盖因除法而导致的有效增益降低 正常化。在这个项目中，我们将使用一个利用移动点刺激的视觉搜索任务来验证这一假设。 具体地说，我们将从MT(运动处理区域)和Lip区域的单个神经元记录动物 执行视觉搜索任务，其中阵列中的1、2或4个对象正在移动点图案。如果一个目标方向 如果有，那么动物必须看着它，否则，它们必须保持注视。我们会改变信号并 每个补丁中的点的颜色，并将有三个注意条件。在空间注意条件下， 动物被空间提示，指示目标将出现在哪个位置，如果它出现的话。在特写中- 根据注意条件，动物被给予一个颜色提示，如果目标出现，将出现在一个带有 点的颜色与球杆相同。在注意力分散的情况下，动物不会得到任何提示。我们会做模特 基于我们的假设以及MT和LIP中的活动的行为(正确率和反应时间)。 然后，我们将通过药物操作前部眼球区域的反应来直接检验这一假设 同时记录LIP和MT的行为和神经元数据。我们预计，我们的结果将有助于 我们在场景中处理视觉信息的有限能力背后的神经机制，但也可以 表明注意调节的功能作用已经被研究了近30年。

Project Summary For centuries, magicians and illusionists have known that if they distract your gaze and attention, you are unlikely to notice what they are doing in plain sight. This inattentional blindness is a result of our limited ability to take in everything about the visual scene and is traditionally illustrated in the lab by set-size effects in visual search: the more items you have to search through, the harder it is to find what you are looking for and the longer it takes. We have recently found that this limitation does not appear to involve visual processing in visual areas, but takes place as the visual information is passed up to association cortices. We hypothesized that divisive normalization in the lateral intraparietal area (LIP) of posterior parietal cortex plays a key role in this process. Our hypothesis combines our knowledge of the neurophysiology of attention, divisive normalization and decision making to explain the behavioral effects associated with changes in set-size. Specifically, we have suggested that when looking for an item, activity in LIP represents the accumulation of evidence from visual areas that the item is in the neuron's response field and if the activity reaches a threshold before a deadline, the animal indicates that the item is in that location. This accumulation is affected by divisive normalization: the more items in the visual world, the more activity across the area and the greater the normalization, resulting in lower accumulation rates. We know that visual attention enhances responses in visual areas, and propose that this effective increase in gain in the input to LIP helps override the effective gain decrease due to the divisive normalization. In this project, we will test this hypothesis using a visual search task utilizing moving dot stimuli. Specifically, we will record from single neurons in areas MT (a motion processing area) and LIP while animals perform a visual search task in which the 1, 2 or 4 objects in the array are moving dot patterns. If a target direction is present, then the animals must look at it, otherwise, they must maintain fixation. We will vary the signal and the color of the dots in each patch and will have three attentional conditions. In the spatial attention condition, the animal is spatially cued, indicating which location the target will appear in, if it appears at all. In the feature- based attention condition, the animal is given a color cue and the target, if it appears, will appear in a patch with dots the same color as the cue. In the spread attention condition, the animal is not given any cue. We will model the behavior (both percent correct and reaction times) based on our hypothesis and the activity in MT and LIP. We will then directly test this hypothesis, by pharmacologically manipulating responses in the frontal eye field while recording behavioral and neuronal data from LIP and MT. We expect that our results will shed light on the neuronal mechanisms underlying our limited ability to process visual information in the scene, but could also indicate a functional role for the attentional modulation that has been studied for almost 30 years.