Attention to Color Sharpens Neural Population Tuning via Feedback Processing in the Human Visual Cortex Hierarchy
Attention to Color Sharpens Neural Population Tuning via Feedback Processing in the Human Visual Cortex Hierarchy
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DOI：
10.1523/jneurosci.0666-17.2017
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发表时间：
2017-10-25
影响因子：
5.3
通讯作者：
Hopf, Jens-Max
中科院分区：
文献类型：
--
作者：
Bartsch, Mandy V.;Loewe, Kristian;Hopf, Jens-Max
注意力可以促进基本对象特征的选择，例如颜色、方向或运动。这被称为基于特征的注意力，通常归因于视觉皮层中增益的调制和特征选择单元的调整。尽管增益机制已得到很好的表征，但对于特征选择性锐化背后的皮层过程却知之甚少。在这里，我们通过人类观察者（男性和女性）的高分辨率脑磁图显示，人类视觉皮层层次结构中的反馈处理产生了对特定颜色的敏锐选择性。为了评估颜色选择性，我们分析了对颜色探针的响应，该探针与关注的颜色目标的颜色距离不同。我们发现注意力会导致前腹侧外纹皮层的初始增益增强，该增强对目标颜色有粗略的选择性，并在大约 100 毫秒内转变为更后腹侧枕叶皮层的更清晰的调谐轮廓。我们得出的结论是，随着时间的推移，注意力通过减弱皮质层次结构较低层对颜色空间中与目标相邻的颜色值的响应来增强选择性。这些观察结果支持计算模型，提出注意力通过对目标调整较少的单元的向后传播衰减来调整视觉皮层的特征选择性。
Attention can facilitate the selection of elementary object features such as color, orientation, or motion. This is referred to as feature-based attention and it is commonly attributed to a modulation of the gain and tuning of feature-selective units in visual cortex. Although gain mechanisms are well characterized, little is known about the cortical processes underlying the sharpening of feature selectivity. Here, we show with high-resolution magnetoencephalography in human observers (men and women) that sharpened selectivity for a particular color arises from feedback processing in the human visual cortex hierarchy. To assess color selectivity, we analyze the response to a color probe that varies in color distance from an attended color target. We find that attention causes an initial gain enhancement in anterior ventral extrastriate cortex that is coarsely selective for the target color and transitions within similar to 100 ms into a sharper tuned profile in more posterior ventral occipital cortex. We conclude that attention sharpens selectivity over time by attenuating the response at lower levels of the cortical hierarchy to color values neighboring the target in color space. These observations support computational models proposing that attention tunes feature selectivity in visual cortex through backward-propagating attenuation of units less tuned to the target.