Heywood Charles A, Kentridge Robert W
Department of Psychology, Wolfson Research Institute, University of Durham, Durham DH1 3LE, United Kingdom.
Neurol Clin. 2003 May;21(2):483-500. doi: 10.1016/s0733-8619(02)00102-0.
Brain damage can entirely abolish color vision in cases of complete achromatopsia. Other processes that depend on wavelength differences, however, can be retained. Form and motion defined by pure color differences can be perceived readily even when the colors themselves cannot be told apart. The loss of color vision in cerebral achromatopsia has been equated with the loss of a "color center" presumed indispensable for the phenomenal experience of hue. The "color center" has been assigned a role in the cortical construction of color, specifically in implementing the computations that underlie color constancy. Many features of the condition are consistent with this account. Other neurologic patients, however, retain conscious experience of hue, yet fail to disentangle the illuminant and the reflectance properties of surfaces. For them, color experience is determined by the wavelength composition of light reflected from a surface. If their wavelength-dependent vision is mediated by activity in early visual areas, then it is difficult to understand why these areas are unable to perform a similar role when they remain intact in achromatopsic observers. The prevalence of cells in the ventral visual areas of the monkey brain that code color and the further fractionation of color-related areas in human observers revealed by functional imaging suggest multiple color areas. Their different contributions are only just beginning to become apparent.
在完全性色盲的情况下，脑损伤可完全消除色觉。然而，其他依赖于波长差异的过程却可以保留下来。即使无法区分颜色本身，由纯颜色差异定义的形状和运动也能很容易被感知。大脑性色盲中色觉的丧失被等同于一个“颜色中心”的丧失，这个“颜色中心”被认为是色调现象体验不可或缺的。“颜色中心”在颜色的皮层构建中被赋予了一个角色，特别是在执行构成颜色恒常性基础的计算方面。这种情况的许多特征都与这种解释相一致。然而，其他神经疾病患者仍保留着对色调的有意识体验，但却无法区分光源和表面的反射特性。对他们来说，颜色体验是由从表面反射的光的波长组成决定的。如果他们依赖波长的视觉是由早期视觉区域的活动介导的，那么就很难理解为什么当这些区域在色盲观察者中保持完整时却无法发挥类似的作用。猴子大脑腹侧视觉区域中编码颜色的细胞的普遍存在以及功能成像揭示的人类观察者中与颜色相关区域的进一步细分表明存在多个颜色区域。它们的不同贡献才刚刚开始显现出来。
