Cortical circuit mechanisms of visual shape processing

项目总结 人类和其他灵长类动物依靠视觉形状信息来识别物体并与之互动 世界。这个项目的目标是获得对灵长类大脑皮层如何处理的机械性洞察。 视觉形状信息。皮质区V4是这些机制研究的理想部位，因为许多V4 神经元根据视觉形状进行调整，显示出沿对象的凸段或凹段的偏好 边界轮廓。这种对视觉形状的调整被认为是行为相关对象的基础 但我们对其机械性实施知之甚少。主要是，我们不知道是哪种皮质 通路和细胞类型负责在V4神经元中产生这种调节。在这个项目中，我们将从 通过利用病毒载体介导的猴子特定细胞类型的光遗传学来填补这些知识空白。在……里面 目标1，我们将问：V4中的视觉形状处理如何依赖于来自 早期皮质区V1和V2？与此目标相关的实验将检验前馈假设 V2区的兴奋是决定V4神经元形状调谐的主要因素。在目标2中，我们将 问：V4中的视觉形状处理如何依赖于该区域内的局部抑制信号？这个 与这一目标相关的实验将检验抑制性神经元根据形状进行调整的假设，并且 局部抑制提高了兴奋性神经元的调谐能力。实现这些目标将首先提供关键的 深入了解前馈兴奋和局部抑制在视觉形状加工中的作用。更深一层的 对灵长类动物的这些皮质回路机制的了解有可能改变 我们治疗形觉障碍，如视觉失认。先进的神经回路光遗传技术 对猴子的解剖也将有助于研究其他复杂的大脑功能，这些功能是特定于 灵长类：推进基础科学和人类医学的当务之急。

PROJECT SUMMARY Humans and other primates rely on using visual shape information to identify and interact with objects in the world. The goal of this project is to gain mechanistic insights into how the primate cerebral cortex processes visual shape information. Cortical area V4 is an ideal locus for these mechanistic studies because many V4 neurons are tuned for visual shape, showing preferences for convex or concave segments along an object's bounding contour. This tuning for visual shape is presumed to be a foundation for behaviorally relevant object representations, but we know little about its mechanistic implementation. Chiefly, we do not know which cortical pathways and cell types are responsible for generating this tuning in V4 neurons. In this project, we will begin to fill these knowledge gaps by employing viral vector-mediated, cell type-specific optogenetics in monkeys. In Aim 1, we will ask: How does visual shape processing in V4 depend on feedforward excitatory signals from earlier cortical areas V1 and V2? The experiments related to this aim will test the hypothesis that feedforward excitation from area V2 is the dominant factor in dictating the shape tuning of V4 neurons. In Aim 2, we will ask: How does visual shape processing in V4 depend on local inhibitory signals within this area? The experiments related to this aim will test the hypothesis that inhibitory neurons are tuned for shape, and that local inhibition sharpens the tuning of excitatory neurons. Accomplishing these aims will provide critical first insights into the role of feedforward excitation and local inhibition in visual shape processing. A deeper understanding of these cortical circuit mechanisms in primates has the potential to transform the way in which we treat disorders of form vision such as visual agnosia. Advancing optogenetic techniques for neural circuit dissection in monkeys will also facilitate the investigation of other complex brain functions that are specific to primates: an imperative for advancing basic science and human medicine.