Land E H, Hubel D H, Livingstone M S, Perry S H, Burns M M
Nature. 1983;303(5918):616-8. doi: 10.1038/303616a0.
Human vision has the remarkable property that, over a wide range, changes in the wavelength composition of the source light illuminating a scene result in very little change in the colour of any of the objects. This colour constancy can be explained by the retinex theory, which predicts the colour of a point on any object from a computed relationship between the radiation from that point and the radiation from all the other points in the field of view (Fig. 1). Thus the computations for colour perception occur across large distances in the visual field. It has not been clear, however, whether these long-range interactions take place in the retina or the cortex. Reports that long-range colour interactions can be reproduced binocularly when one band of wavelengths enters one eye and a different band enters the other might seem to establish the cortex as the site of the computation. Many observers, however, see very unsatisfactory colour or no colour at all in this binocular situation, suggesting that the cortex may not be the only site at which the computation is carried out, or even the most important site. We have now tested the role of the cortex in a human subject in whom the nerve fibres connecting cortical areas subserving two separate parts of the visual field had been severed, and find that the cortex is necessary for long-range colour computations.
人类视觉具有非凡的特性，即在很大范围内，照亮场景的光源的波长组成发生变化时，场景中任何物体的颜色变化都非常小。这种颜色恒常性可以用视网膜皮层理论来解释，该理论根据某一点的辐射与视野中所有其他点的辐射之间的计算关系来预测任何物体上某一点的颜色（图1）。因此，颜色感知的计算是在视野中的远距离上进行的。然而，目前尚不清楚这些远距离相互作用是发生在视网膜还是皮层。当一个波长带进入一只眼睛而另一个不同的波长带进入另一只眼睛时，可以双眼重现远距离颜色相互作用的报告，似乎表明皮层是进行计算的部位。然而，许多观察者在这种双眼情况下看到的颜色非常不理想或根本看不到颜色，这表明皮层可能不是进行计算的唯一部位，甚至不是最重要的部位。我们现在在一名人类受试者身上测试了皮层的作用，该受试者中连接服务于视野两个不同部分的皮层区域的神经纤维已经被切断，结果发现皮层对于远距离颜色计算是必要的。
