Li Ran, Wang Yi
1] State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China [2] University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Rep. 2013 Nov 7;3:3159. doi: 10.1038/srep03159.
Luminance is a fundamental property of visual scenes. A population of neurons in primary visual cortex (V1) is sensitive to uniform luminance. In natural vision, however, the retinal image often changes rapidly. Consequently the luminance signals visual cells receive are transiently varying. How V1 neurons respond to such luminance changes is unknown. By applying large static uniform stimuli or grating stimuli altering at 25 Hz that resemble the rapid luminance changes in the environment, we show that approximately 40% V1 cells responded to rapid luminance changes of uniform stimuli. Most of them strongly preferred luminance decrements. Importantly, when tested with drifting gratings, the preferred speeds of these cells were significantly higher than cells responsive to static grating stimuli but not to uniform stimuli. This responsiveness can be accounted for by the preferences for low spatial frequencies and high temporal frequencies. These luminance-sensitive cells subserve the detection of fast motion under the conditions of dim illumination.
亮度是视觉场景的一个基本属性。初级视觉皮层（V1）中的一群神经元对均匀亮度敏感。然而，在自然视觉中，视网膜图像常常快速变化。因此，视觉细胞接收到的亮度信号是瞬变的。V1神经元如何对这种亮度变化做出反应尚不清楚。通过施加大型静态均匀刺激或25Hz变化的光栅刺激（类似于环境中的快速亮度变化），我们发现约40%的V1细胞对均匀刺激的快速亮度变化有反应。其中大多数强烈偏好亮度降低。重要的是，当用漂移光栅进行测试时，这些细胞的偏好速度显著高于对静态光栅刺激有反应但对均匀刺激无反应的细胞。这种反应性可以通过对低空间频率和高时间频率的偏好来解释。这些亮度敏感细胞有助于在弱光条件下检测快速运动。
