Smallman H S, MacLeod D I, He S, Kentridge R W
Smith-Kettlewell Eye Research Institute, San Francisco, California 94115, USA.
J Neurosci. 1996 Mar 1;16(5):1852-9. doi: 10.1523/JNEUROSCI.16-05-01852.1996.
It is widely held that in human spatial vision the visual scene is initially processed through visual filters, each of which is responsive to narrow ranges of image spatial frequencies. The physiological basis of these filters are thought to be cortical neurons with receptive fields of different sizes. The grain of the neural representation of spatial vision is much finer than had been supposed. Using laser interferometry, which effectively bypasses the demodulation of the optics of the eye, we measured discrimination of, and adaptation to, high spatial frequency laser interference fringe patterns. Spatial frequency discrimination was good right up to the visual resolution limit (average Weber fractions of 0.13 at 50 c/deg). Both contrast and spatial frequency matches made after adapting to extremely fine interference fringes strongly suggested that there existed even finer, relatively unadapted, filters (mechanisms with small receptive fields). The smallest cortical receptive fields processing spatial information in human vision are so small that they can possess receptive field centers hardly wider than single cone photoreceptors.
人们普遍认为，在人类空间视觉中，视觉场景最初是通过视觉滤波器进行处理的，每个滤波器对狭窄范围的图像空间频率有响应。这些滤波器的生理基础被认为是具有不同大小感受野的皮质神经元。空间视觉的神经表征颗粒比之前认为的要精细得多。使用激光干涉测量法，该方法有效地绕过了眼睛光学系统的解调过程，我们测量了对高空间频率激光干涉条纹图案的辨别和适应情况。空间频率辨别能力一直良好，直至视觉分辨率极限（在50周/度时平均韦伯分数为0.13）。在适应极其精细的干涉条纹后进行的对比度和空间频率匹配都强烈表明，存在更精细、相对未适应的滤波器（具有小感受野的机制）。在人类视觉中处理空间信息的最小皮质感受野非常小，以至于它们的感受野中心几乎不比单个视锥光感受器宽。
