Columnar Organization of Surface vs. Border Information in Human Areas V2 and V3

项目摘要/摘要 超过三分之一的人类大脑皮层对视觉信息做出反应，视觉信息通过 初级视皮层(V1)。因此，对V1处理有很多了解。然而，我们知道的要少得多。 关于“下”皮质区(V2)的信息处理，对更高的V3区的信息处理更是知之甚少。在……里面 V2的动物研究，理解信息加工的关键之一是不同类型的刺激 这些特征是在分离的皮质柱“条纹”中独立处理的。一套柱状条纹 有选择地响应颜色的变化，这是一种表面特性。另一组柱的响应最好 基于立体(‘3D’)刺激的边界变化(因此，后一项研究可以阐明机制 潜在弱视)。对这种柱的研究可以揭示组成神经元的基本反应。 此前，人类是否存在这样的功能条/柱一直是个未知数。传统型 功能磁共振成像(FMRI)技术无法在空间上解析这样的柱，这些柱是 很小。通过使用专门的fMRI方法(7T，1mm3)，我们在这里成功地演示了(并已 开始分析)人类区域V2和V3中的这种柱和条纹。除了简单地想象这样的柱子， 我们建议检验一个新的假说：早期视觉皮质在两个阶段处理边界与表面特征。 并行流，分别位于V2中的细条和粗条内。我们还测试了表面-与- 然后，将边界信息向前传递到V3中的分离列。如果得到证实，这一假设将 澄清(并帮助统一)关于早期视觉皮质功能处理性质的各种现有数据。 目标1将通过呈现不同类型的刺激边界或表面属性来测试我们的假设， 分别在粗条纹或细条纹中测试相应的更高响应。五个子目标中的每一个都将 隔离并测试对由以下两项中的差异定义的边界的反应：双目视差(子目标1.1)，或 运动方向(1.2)、纹理(1.3)、颜色(1.4)或亮度(1.5)。 目标2以一种补充的方式测试目标1的结论，提出的刺激只包括 单个边界，在视野的每个象限，以及在相应的皮质地图中。目标3.1和3.2 将在视网膜定位预测的粗条(和相关的V3列)中测试更高的活性 推断出的或虚幻的轮廓。AIM 3.3中使用的刺激预测了瘦与瘦之间的活动转变 粗条纹系统，由视网膜特定的彩色表面产生--分别与边界。 视觉空间中的不同点(表面或边界)被映射到皮质表面， 属性，也就是所谓的‘retinotope’映射。因此，柱状图(目标1)与视网膜复制图共存。然而， 目前还不知道这两个地图如何在列的空间分辨率上相互适应。目标3将 澄清细条纹和粗条纹(以及相关的V3列)是否有重复的视网膜定位图(分目标3.1)， 或特定的视网膜原位“间隙”(3.2)，或较小的与较大的视网膜原位扩散。

Project Summary/Abstract More than a third of human cerebral cortex responds to visual information, which enters cortex through primary visual cortex (V1). Accordingly, much is known about V1 processing. However, much less is known about information processing in the `next' cortical area (V2), and even less is known about higher area V3. In animal studies of V2, one key to understanding information processing is that different types of stimulus features are processed ~independently in segregated `stripes' of cortical columns. One set of columnar stripes responds selectively to variations in color, a surface property. Another set of columns responds best to variations in boundaries based on stereoscopic (`3D') stimuli (thus the latter research can clarify mechanisms underlying amblyopia). Study of such columns can reveal fundamental responses in the component neurons. Previously, it has been unknown whether such functional stripes/columns exist in humans. Conventional functional magnetic resonance imaging (fMRI) techniques cannot spatially resolve such columns, which are quite small. By using a specialized fMRI approach (7T, 1 mm3), here we successfully demonstrated (and have begun analyzing) such columns and stripes in human areas V2 and V3. Beyond simply imaging such columns, we propose to test a new hypothesis: early visual cortex processes boundaries vs. surface features, in two parallel streams, within thin and thick stripes (respectively) in V2. We also test whether that surface-vs.- boundary information is then passed forward to segregated columns in V3. If confirmed, this hypothesis will clarify (and help unify) the diverse existing data about the nature of functional processing in early visual cortex. Aim 1 will test our hypothesis by presenting different types of stimulus boundaries or surface properties, testing for correspondingly higher responses in thick or thin stripes, respectively. Each of five sub-aims will isolate and test responses to boundaries defined by differences in either: binocular disparity (sub-aim 1.1), or direction of motion (1.2), texture (1.3), color (1.4), or luminance (1.5). Aim 2 tests the conclusions from Aim 1 in a complementary way, by presenting stimuli that include only a single boundary, in each quadrant of the visual field, and in the corresponding cortical map. Aims 3.1 and 3.2 will test for higher activity in retinotopically-predicted subregions in thick stripes (and related V3 columns) due to inferred or illusory contours. The stimulus used in aim 3.3 predicts a shift in activity between the thin vs. thick stripe systems, produced by retinotopically specific colored surfaces- vs. boundaries, respectively. Different points in visual space (either surfaces or boundaries) are mapped onto the cortical surface, a property known as `retinotopic' mapping. Thus the columns (aim 1) co-exist with maps of retinotopy. However It is not known how these two maps accommodate each other at the spatial resolution of columns. Aim 3 will clarify whether thin vs. thick stripes (and related V3 columns) have duplicated retinotopic maps (sub-aim 3.1), or specific retinotopic `gaps' (3.2), or smaller vs. greater retinotopic spread, respectively.