Neural Mechanisms for Feature-Based Attention

我们必须经常在杂乱的场景中寻找与我们的行为直接相关的物品--例如我们的食物，我们的汽车 钥匙，我们的朋友，等等。在每种情况下，我们都使用目标对象特征的记忆来有效地引导 我们搜索具有某些共同特征的对象，这样我们就不会被迫检查 人头攒动的场面。高效的视觉搜索对于高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潜在生物学机制已知很多， 人们对基于特征选择对象的基本机制知之甚少。去设计 有效的神经假体或治疗有感觉或注意力障碍的人，我们需要更好的 在系统层面上理解功能注意。对特征注意的更好理解也将 让我们更深入地了解视觉工作记忆和视觉记忆回忆的潜在机制，如 这些相关的功能似乎至少涉及部分重叠的神经回路。直到最近，它一直是 不清楚是否有任何特定的大脑结构来存储和使用有关注意到的特征的信息 通过自上而下的反馈来指导大脑皮层的视觉处理。我们最近获得了这样一种证据 位于前额叶皮质，我们称之为VPA的区域。我们的目标是专注于更好的 对VPA的理解及其在注意时与其他视觉区域相互作用的机制 功能。在目标1中，我们将使用电刺激和功能磁共振成像来密集地映射广泛的 广泛的外侧前额叶皮质，包括VPA。这张前额叶“连接体”将向我们展示VPA之间的关系 到其他前额叶回路，它将给我们提供VPA如何与其他 整个大脑的功能区。出版的连接体也将成为 神经科学界。来自连接组的初步结果已经被用来指导我们的另一个 两个目标。在目标2中，我们将使用药理学方法可逆地使VPA失活，以检验我们的假设 VPA是反馈的来源，在注意诸如以下特征的过程中调制区域V4的处理 形状和颜色。积极的结果将是支持VPA对腹侧的反馈控制的有力证据 用于对象识别的流。在目标3中，我们将测试我们关于VPA在背流中的作用的假设， 在注意到物体的运动方向的过程中。VPA、MT、MST、FST和LIP中的单元格 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来 光基因抑制VPA，并测试它是否损害对运动的注意力，减少或消除 注意运动对MT、MST、FST和LIP区细胞反应的影响。总体而言，我们预计 这些研究向我们提供了迄今为止最好的解释，说明VPA与多种脑结构的相互作用 导致在注意物体特征的过程中进行有效的视觉处理。

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.