Schluppeck Denis, Engel Stephen A
UCLA Department of Psychology, Los Angeles, CA, USA.
J Vis. 2002;2(6):480-92. doi: 10.1167/2.6.5.
The signals in visual cortex that ultimately give rise to color perception remain poorly understood. Controversy has particularly surrounded one aspect of color's encoding in the visual system-opponent processing in primary visual cortex. Early single-unit studies suggested that V1 contains relatively few color-opponent neurons. Neuroimaging measurements, however, have suggested that such neurons might be relatively numerous. Here, we reconcile these apparently discrepant results and conclude that V1 contains relatively large numbers of color-opponent neurons. We first review results from each method and find that most neuroimaging studies provide evidence of substantial color opponency in V1, and that despite apparent controversy, most single-unit studies agree that relatively large numbers of V1 neurons show some sort of color opponency. To reconcile the results from different techniques more formally, we used electrophysiological data to predict the outcomes of neuroimaging experiments. We simulated the expected fMRI response in V1 to spatial patterns of different color, based on the neurons' properties, as reported in Johnson, Hawken, and Shapley, (2001). The simulated responses to stimuli used in Engel, Zhang, and Wandell, (1997) agree well with the actually observed fMRI results. The model identifies several factors that led to the apparent discrepancy between techniques, and makes testable predictions about how these factors influence the magnitude of color-opponent signals. fMRI and single-unit data converge to show that large numbers of color-opponent neurons exist in V1.
视觉皮层中最终产生颜色感知的信号仍未得到充分理解。争议尤其围绕着视觉系统中颜色编码的一个方面——初级视觉皮层中的对立处理。早期的单神经元研究表明，V1中相对较少存在颜色对立神经元。然而，神经成像测量表明，这类神经元可能相对较多。在这里，我们调和了这些明显矛盾的结果，并得出结论，V1中存在相对大量的颜色对立神经元。我们首先回顾了每种方法的结果，发现大多数神经成像研究提供了V1中存在大量颜色对立的证据，并且尽管存在明显的争议，但大多数单神经元研究都一致认为，相对大量的V1神经元表现出某种颜色对立。为了更正式地调和不同技术的结果，我们使用电生理数据来预测神经成像实验的结果。我们根据Johnson、Hawken和Shapley（2001年）报道的神经元特性，模拟了V1对不同颜色空间模式的预期功能磁共振成像反应。对Engel、Zhang和Wandell（1997年）使用的刺激的模拟反应与实际观察到的功能磁共振成像结果非常吻合。该模型确定了导致技术之间明显差异的几个因素，并对这些因素如何影响颜色对立信号的大小做出了可检验的预测。功能磁共振成像和单神经元数据一致表明，V1中存在大量颜色对立神经元。
