Different roles of subcortical inputs in V1 responses to luminance and contrast
Different roles of subcortical inputs in V1 responses to luminance and contrast
复制标题
皮层下输入在 V1 对亮度和对比度的反应中的不同作用
DOI：
10.1111/ejn.15233
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发表时间：
2021-05-09
影响因子：
3.4
通讯作者：
Wang，Yi
中科院分区：
文献类型：
--
作者：
Tang，Rendong;Chen，Wenzhen;Wang，Yi
初级视觉皮质（V1）中的细胞通常对大的均匀亮度刺激反应较弱。仅V1单元的子集被认为编码均匀亮度信息。在自然场景中，局部亮度是定义与局部空间对比度变化并共存的对象的重要特征。然而，V1细胞编码局部平均亮度的空间对比度刺激的策略在很大程度上仍然不清楚。在这里，使用细胞外记录在麻醉猫，我们调查的V1细胞的反应，通过比较与视网膜神经节（RG）细胞和外侧膝状体核（LGN）细胞的亮度和空间对比度的同时和快速变化。几乎所有的V1细胞表现出强烈的单调增加亮度调谐时，他们暴露于高空间对比度。因此，V1细胞编码的亮度进行空间对比度刺激与单调递增的响应函数。此外，高对比度降低了RG和LGN中OFF细胞的亮度调谐，但增加了ON细胞的亮度调谐。LGN ON细胞的亮度和对比度调谐与V1细胞一样具有高度可分离性，而LGN OFF细胞的亮度和对比度调谐具有低可分离性。ON/OFF通道上的空间对比度的这些不对称效应可能是V1细胞在暴露于空间对比度刺激时执行亮度调节的强大能力的基础。
Cells in the primary visual cortex (V1) generally respond weakly to large uniform luminance stimuli. Only a subset of V1 cells is thought to encode uniform luminance information. In natural scenes, local luminance is an important feature for defining an object that varies and coexists with local spatial contrast. However, the strategies used by V1 cells to encode local mean luminance for spatial contrast stimuli remain largely unclear. Here, using extracellular recordings in anesthetized cats, we investigated the responses of V1 cells by comparing with those of retinal ganglion (RG) cells and lateral geniculate nucleus (LGN) cells to simultaneous and rapid changes in luminance and spatial contrast. Almost all V1 cells exhibited a strong monotonic increasing luminance tuning when they were exposed to high spatial contrast. Thus, V1 cells encode the luminance carried by spatial contrast stimuli with the monotonically increasing response function. Moreover, high contrast decreased luminance tuning of OFF cells but increased that of in ON cells in RG and LGN. The luminance and contrast tunings of LGN ON cells were highly separable as V1 cells, whereas those of LGN OFF cells were lowly separable. These asymmetrical effects of spatial contrast on ON/OFF channels might underlie the robust ability of V1 cells to perform luminance tuning when exposed to spatial contrast stimuli.