Blessing Esther M, Solomon Samuel G, Hashemi-Nezhad Maziar, Morris Brian J, Martin Paul R
National Vision Research Institute of Australia, Cnr Keppel and Cardigan Streets, Carlton, VIC 3053, Australia.
J Physiol. 2004 May 15;557(Pt 1):229-45. doi: 10.1113/jphysiol.2003.058065. Epub 2004 Mar 26.
The parvocellular (PC) division of the afferent visual pathway is considered to carry neuronal signals which underlie the red-green dimension of colour vision as well as high-resolution spatial vision. In order to understand the origin of these signals, and the way in which they are combined, the responses of PC cells in dichromatic ('red-green colour-blind') and trichromatic marmosets were compared. Visual stimuli included coloured and achromatic gratings, and spatially uniform red and green lights presented at varying temporal phases and frequencies.The sensitivity of PC cells to red-green chromatic modulation was found to depend primarily on the spectral separation between the medium- and long-wavelength-sensitive cone pigments (20 or 7 nm) in the two trichromatic marmoset phenotypes studied. The temporal frequency dependence of chromatic sensitivity was consistent with centre-surround interactions. Some evidence for chromatic selectivity was seen in peripheral PC cells. The receptive field dimensions of parvocellular cells were similar in dichromatic and trichromatic animals, but the achromatic contrast sensitivity of cells was slightly higher (by about 30%) in dichromats than in trichromats. These data support the hypothesis that the primary role of the PC is to transmit high-acuity spatial signals, with red-green opponent signals appearing as an additional response dimension in trichromatic animals.
视觉传入通路的小细胞（PC）部分被认为携带神经元信号，这些信号构成了色觉的红绿色维度以及高分辨率空间视觉的基础。为了理解这些信号的起源以及它们的组合方式，比较了双色（“红绿色盲”）和三色狨猴中PC细胞的反应。视觉刺激包括彩色和无色光栅，以及在不同时间相位和频率呈现的空间均匀的红光和绿光。研究发现，PC细胞对红绿色调制的敏感性主要取决于所研究的两种三色狨猴表型中中波和长波敏感视锥色素之间的光谱分离（20或7纳米）。色敏度的时间频率依赖性与中心-外周相互作用一致。在外周PC细胞中观察到了一些色选择性的证据。双色和三色动物中小细胞的感受野尺寸相似，但双色动物中细胞的无色对比度敏感性比三色动物略高（约30%）。这些数据支持了这样一种假设，即PC的主要作用是传输高敏锐度的空间信号，红绿色拮抗信号在三色动物中作为额外的反应维度出现。
