Department of Psychology and Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada.
J Neurophysiol. 2012 Sep;108(5):1381-91. doi: 10.1152/jn.01148.2011. Epub 2012 Jun 13.
Contrast adaptation is a commonly studied phenomenon in vision, where prolonged exposure to spatial contrast alters perceived stimulus contrast and produces characteristic shifts in the contrast response functions of primary visual cortex neurons in cats and primates. In this study we investigated contrast adaptation in mouse primary visual cortex with two goals in mind. First, we sought to establish a quantitative description of contrast adaptation in an animal model, where genetic tools are more readily applicable to this phenomenon. Second, the orientation specificity of contrast adaptation was studied to comparatively assess the possible role of local cortical networks in contrast adaptation. In cats and primates, predictable differences in visual processing across the cortical surface are thought to be caused by inhomogeneous local network membership that arises from the pinwheel organization of orientation columns. Because mice lack this pinwheel organization, we predicted that local cortical networks would have access to a broad spectrum of orientation signals, and contrast adaptation in mice would not be specific to the recorded cell's preferred orientation. We found that most mouse V1 neurons showed contrast adaptation that was robust regardless of whether the adapting stimulus matched the cell's preferred orientation or was orthogonal to it.
对比适应是视觉中一个常见的研究现象，在这种现象中，长时间暴露于空间对比度会改变感知到的刺激对比度，并在猫和灵长类动物的初级视觉皮层神经元的对比响应函数中产生特征性的变化。在这项研究中，我们考虑了两个目标，研究了小鼠初级视觉皮层中的对比适应。首先，我们试图在动物模型中建立对比适应的定量描述，在这种模型中，遗传工具更易于应用于这种现象。其次，研究了对比适应的方向特异性，以比较评估局部皮质网络在对比适应中的可能作用。在猫和灵长类动物中，皮质表面上可预测的视觉处理差异被认为是由起源于方向柱的轮辐组织的不均匀局部网络成员造成的。由于小鼠缺乏这种轮辐组织，我们预测局部皮质网络将能够获得广泛的方向信号，并且小鼠的对比适应不会特定于记录细胞的首选方向。我们发现，大多数小鼠 V1 神经元表现出的对比适应非常稳健，无论适应刺激是否与细胞的首选方向匹配，或者是否与之正交。
