Neural Mechanisms for Feature-Based Attention

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 在每种情况下，我们都使用目标对象的特征记忆来有效地引导 我们的搜索对象，共享它的一些功能，使我们不必检查每一个对象在一个 单独拥挤的场景。有效的视觉搜索对于有效的视觉引导行为至关重要。虽然 关于基于空间位置选择对象的生物学机制已经知道很多， 对基于特征选择对象的机制知之甚少。设计 一个有效的神经假体或治疗感官或注意力障碍的人，我们需要一个更好的 在系统级别上理解特征注意力。更好地理解特征关注度还将 让我们更深入地了解视觉工作记忆和视觉记忆回忆的机制， 这些相关的功能似乎涉及至少部分重叠的神经回路。直到最近， 不清楚是否有任何特定的大脑结构存储有关关注特征的信息并使用它 通过自上而下的反馈来引导大脑皮层的视觉处理。我们最近获得的证据表明， 位于前额叶皮层，我们称之为VPA。我们的目标是专注于更好的 了解VPA及其在注意过程中与其他视觉区域相互作用的机制， 功能.在目标1中，我们将使用电刺激与fMRI配对，以密集地映射宽脑区的投射。 外侧前额叶皮层包括VPA这个前额叶“连接体”将向我们展示VPA是如何与 它将为我们提供VPA如何与其他前额叶回路相互作用的神经线路图， 整个大脑的功能区域。已发表的连接体也将作为研究 神经科学社区连接体的初步结果已经被用来指导我们的其他研究。 两个目标。在目标2中，我们将使用药理学方法可逆地灭活VPA，以验证我们的假设 VPA是反馈的来源，它在注意特征时调节V4区的处理， 形状和颜色。一个积极的结果将是有力的证据，有利于VPA反馈控制腹侧 用于对象识别流。在目标3中，我们将检验我们关于VPA在背侧流中作用的假设， 在注意物体的过程中基于它们的运动方向。VPA、MT、MST、FST和LIP中的细胞将 同时记录，以测试VPA中的神经活动是否具有支持 VPA在注意运动中的因果作用。然后我们将使用我们开发的新技术， 光遗传学抑制VPA，并测试它是否会损害对运动的注意力，并减少或消除 注意运动对MT、MST、FST和LIP区细胞反应的影响。总的来说，我们预计 这些研究为我们提供了迄今为止关于VPA如何与多种大脑结构相互作用的最佳解释， 在注意物体特征的过程中导致有效的视觉处理。

We must often search cluttered scenes for items of immediate behavioral relevance – e.g. our food, our car keys, our friend, and so on. In each case, we use a memory of the target object’s features to efficiently guide our search to objects that share some of its features, 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 underlying the selection of objects based on spatial location, much less is known about the mechanisms underlying the selection of objects based on features. To design an effective neural prosthesis or to treat people with sensory or attentional impairments, we need a better understanding of feature attention at the systems level. A better understanding of feature attention will also give us more insight into the mechanisms underlying visual working memory and visual memory recall, as these related functions seem to involve at least partially overlapping neural circuits. Until recently, it was unclear if there was any specific brain structure that stored the information about attended features and used it to guide visual processing in the cortex through top-down feedback. We recently obtained evidence for such a site in prefrontal cortex, in a region that we have termed VPA. Our Aims are focused on a better understanding of VPA and the mechanisms by which it interacts with other visual areas during attention to features. In Aim 1, we will use electrical stimulation paired with fMRI to densely map the projections of a wide expanse of lateral prefrontal cortex, including VPA. This prefrontal “connectome” will show us how VPA relates to other prefrontal circuits, and it will give us the neural wiring diagram for how VPA interacts with other functional regions throughout the brain. The published connectome will also serve as valuable resource for the neuroscience community. Preliminary results from the connectome are already being used to guide our other two Aims. In Aim 2, we will use pharmacological methods to reversibly deactivate VPA, to test our hypotheses that VPA is the source of feedback that modulates processing in area V4 during attention to features such as shape and color. A positive result would be strong evidence in favor of VPAs feedback control of the ventral stream for object recognition. In Aim 3, we will test our hypotheses about the role of VPA in the dorsal stream, during attention to objects based on their direction of motion. Cells in VPA, MT, MST, FST, and LIP will be recorded simultaneously, to test whether neural activity in VPA has the temporal properties needed to support VPA’s causal role in attention to motion. We will then use new technology we have developed to optogenetically suppress VPA and test whether it impairs attention to motion and reduces or eliminates the effects of attention to motion on the responses of cells in areas MT, MST, FST, and LIP. In total, we expect these studies to give us the best account so far of how the interactions of VPA with multiple brain structures leads to effective visual processing during attention to object features.