Functional Architectural of Area V4

V4区是灵长类视觉皮层的一个关键组成部分，参与了“中间”处理的许多方面，包括高阶形状处理，颜色恒定性和注意力。V4执行比较低区域V1或V2更复杂的计算，但它不完成在颞叶中发生的对象分析。尽管对单个V4神经元的特性有相当多的了解，但对V4神经元群体如何代表简单和更复杂的视觉特征知之甚少。最近的实验表明，V4取向的首选区域由小的等取向集群，系统地转移，形成方向图。类似地，V4颜色偏好区域由小的等色相簇组成，这些等色相簇系统地移位以形成风车形、线形或角形色相图。最重要的是，这些方向和颜色偏好的地图部分重叠，导致颜色或方向的单一功能模块和颜色方向的功能连接模块。在拟议的实验中，内在皮层成像将定量地确定，如何首选的颜色和方向的偏好和选择性表示在V4和这些功能是否被组织成单一功能和功能连接模块。电生理记录将确定这些特征图的神经元基础。由于V4模块预计较小（约0.5 - 1 mm宽），因此紧密间隔的微电极阵列将优化对整个皮层神经元颜色和方向调谐的系统差异的检测。V4接收来自V2细条纹和交错条纹的密集的、大部分隔离的输入，细条纹和交错条纹被认为分别传达颜色和形状信息。然而，它仍然在很大程度上是未知的，这些输入如何有助于V4的神经元特性和功能结构。在这些实验中，可区分的神经解剖示踪剂将被注入到两个或多个功能特征的V4模块，以确定其与V2连接的特定模式。这项研究的长期目标是确定不同的视觉特征在视觉皮层的不同层次上是如何表现的，并确定这些结构如何有助于物体识别和记忆。

Area V4 is a key component of primate visual cortex that is involved in many aspects of ‘intermediate’ processing including higher-order shape processing, color constancy, and attention. V4 performs more complex computations than lower areas V1 or V2, but it does not complete object analysis that occurs in the temporal lobe. Despite considerable knowledge about the properties of individual V4 neurons, little is known about how simple and more complex visual features are represented by populations of neurons in V4. Recent experiments indicate that V4 orientation-preferred regions consist of small iso-orientation clusters that systematically shift to form orientation maps. Similarly, V4 color-preferring regions consist of small iso-hue clusters that shift systematically to form pinwheel-, line-, or angle-shaped hue maps. Most importantly, these orientation- and color-preferring maps partially overlap each other, resulting in both color or orientation single-feature modules and color-orientation feature-conjunction modules. In the proposed experiments, intrinsic cortical imaging will determine quantitatively, how preferred color and orientation preference and selectivity are represented in V4 and whether these features are organized into single-feature and feature-conjunction modules. Electrophysiological recording will determine the neuronal bases of these feature maps. Since V4 modules are expected to be small (~0.5-1 mm across), closely spaced microelectrode arrays will optimize the detection of systematic differences in neuronal color and orientation tuning across the cortex. V4 receives dense, largely segregated inputs from V2 thin and interstripes that are thought to convey color and shape information, respectively. However, it remains largely unknown how these inputs contribute to the neuronal properties and functional architecture of V4. In these experiments, distinguishable neuroanatomical tracers will be injected into two or more functionally characterized V4 modules to determine their specific patterns of connections with V2. The long-term goal of this research is to determine how different visual features are represented at different hierarchical levels of visual cortex and to determine how these architectures contributes to object recognition and memory.