Chromatic mechanisms in striate cortex of macaque
Chromatic mechanisms in striate cortex of macaque
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DOI：
10.1523/jneurosci.10-02-00649.1990
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发表时间：
1990-02
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影响因子：
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通讯作者：
P. Lennie;J. Krauskopf;G. Sclar
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作者：
P. Lennie;J. Krauskopf;G. Sclar
我们测量了305个纹状皮层神经元对固定白点色度和亮度调制的正弦光栅的反应。刺激在由2个色轴和沿亮度变化的第三个色轴定义的三维色彩空间中表示。除了少数例外，皮质神经元的颜色特性可以用线性模型很好地描述，在线性模型中，细胞的响应与来自3类视锥细胞的信号的总和成正比（对于复杂细胞，是校正的总和）。对于每个细胞都有一个通过白点的矢量，调制沿着白点产生最大响应。这个向量的仰角（theta m）和方位角（phi m）完全描述了细胞的色属性。线性模型也描述了lg.n中的神经元（Derrington et al., 1984），因此纹状皮层中的大多数神经元与lg.n中的神经元具有相同的颜色选择性。然而，首选向量的分布在皮层和lg.n中有所不同：大多数皮质神经元倾向于沿着靠近无色差轴的矢量进行调制，而那些表现出明显色差的神经元并不属于l.g.n中明确定义的色差组。对色差调制最敏感的神经元（主要存在于IVA、IVC β和VI层）的定向选择性较差，对空间均匀场的色差调制的反应至少与对任何光栅的反应一样好。我们在II/III和VI层中发现了对色彩调制刺激具有带通空间选择性的神经元。大多数神经元具有复杂的感受野。II/III层神经元的颜色敏感性没有明显的分组，已知位于细胞色素氧化酶丰富区域内的神经元的颜色特性与间隙内的神经元没有区别。6个类似于简单细胞的神经元表现出异常敏锐的颜色选择性。
We measured the responses of 305 neurons in striate cortex to moving sinusoidal gratings modulated in chromaticity and luminance about a fixed white point. Stimuli were represented in a 3-dimensional color space defined by 2 chromatic axes and a third along which luminance varied. With rare exceptions the chromatic properties of cortical neurons were well described by a linear model in which the response of a cell is proportional to the sum (for complex cells, the rectified sum) of the signals from the 3 classes of cones. For each cell there is a vector passing through the white point along which modulation gives rise to a maximal response. The elevation (theta m) and azimuth (phi m) of this vector fully describe the chromatic properties of the cell. The linear model also describes neurons in l.g.n. (Derrington et al., 1984), so most neurons in striate cortex have the same chromatic selectivity as do neurons in l.g.n. However, the distributions of preferred vectors differed in cortex and l.g.n.: Most cortical neurons preferred modulation along vectors lying close to the achromatic axis and those showing overt chromatic opponency did not fall into the clearly defined chromatic groups seen in l.g.n. The neurons most responsive to chromatic modulation (found mainly in layers IVA, IVC beta, and VI) had poor orientation selectivity, and responded to chromatic modulation of a spatially uniform field at least as well as they did to any grating. We encountered neurons with band-pass spatial selectivity for chromatically modulated stimuli in layers II/III and VI. Most had complex receptive fields. Neurons in layer II/III did not fall into distinct groups according to their chromatic sensitivities, and the chromatic properties of neurons known to lie within regions rich in cytochrome oxidase appeared no different from those of neurons in the interstices. Six neurons, all of which resembled simple cells, showed unusually sharp chromatic selectivity.