Compressive spatial summation in human visual cortex
Compressive spatial summation in human visual cortex
复制标题
DOI：
10.1152/jn.00105.2013
复制
发表时间：
2013-07-01
影响因子：
2.5
通讯作者：
Wandell, Brian A.
中科院分区：
文献类型：
--
作者：
Kay, Kendrick N.;Winawer, Jonathan;Wandell, Brian A.
视皮层小区域(几立方毫米)内的神经元对视野受限区域内的刺激做出反应。以前的研究已经使用一个模型来描述这种神经元的群体反应，该模型在整个视野内对对比度进行线性求和。在这项研究中，我们使用血氧水平依赖(BOLD)功能MRI测试了人群反应的线性空间总和。我们测量了对一组系统的对比模式的大胆反应，发现了与线性的系统性背离：在线性空间求和之后应用压缩静态非线性的模型可以更准确地解释数据。我们发现，这种非线性存在于早期的视觉区域(如V1、V2)，并在相对较前的纹外区(如LO-2、VO-2)变得更加明显。然后，我们根据观察对象的位置和大小的变化来分析压缩空间总和的效果。压缩空间总和与对位置和大小变化的容忍度一致，这是对象表征的重要特征。
Neurons within a small (a few cubic millimeters) region of visual cortex respond to stimuli within a restricted region of the visual field. Previous studies have characterized the population response of such neurons using a model that sums contrast linearly across the visual field. In this study, we tested linear spatial summation of population responses using blood oxygenation level-dependent (BOLD) functional MRI. We measured BOLD responses to a systematic set of contrast patterns and discovered systematic deviation from linearity: the data are more accurately explained by a model in which a compressive static nonlinearity is applied after linear spatial summation. We found that the nonlinearity is present in early visual areas (e.g., V1, V2) and grows more pronounced in relatively anterior extrastriate areas (e.g., LO-2, VO-2). We then analyzed the effect of compressive spatial summation in terms of changes in the position and size of a viewed object. Compressive spatial summation is consistent with tolerance to changes in position and size, an important characteristic of object representation.