[The spatial frequency limits and the resolving power of the visual system of the pigeon].
[The spatial frequency limits and the resolving power of the visual system of the pigeon].
复制标题
鸽子视觉系统的空间频率限制与分辨能力.
DOI：
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发表时间：
1991
期刊：
影响因子：
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通讯作者：
S. Cleveland
中科院分区：
文献类型：
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作者：
M. Pak;S. Cleveland
鸽子视觉系统的空间对比传递函数是通过记录视觉顶盖的诱发电位或响应模式刺激的细胞外单位活动来确定的，对比传递函数被确定为“响应函数”，描述了模式（由垂直方向的正弦变化亮度的条纹组成）中的对比度与不同空间频率（c/deg）的响应幅度之间的关系。传递函数产生高频极限的估计，这反过来又是视觉分辨能力的度量。用玻璃微电极记录细胞外动作电位；诱发电位采用不锈钢电极。在视神经顶盖的灰质层和浅纤维层进行记录。在视觉系统中可检测到的最高空间频率受到各种因素的限制，包括光在瞳孔处的衍射和光感受器的解剖间距。在实验中，瞳孔因子可以用适当的方法加以控制。本文将电生理测定的高频极限与光感受器镶嵌的理论分辨率极限进行了比较。实验结果表明，鸽子的视觉系统在空间频率为15.5 c/°时具有高频极限，对应的视觉灵敏度为1.9分弧度。将鸽子的视敏度与光感受器的解剖间距联系起来的尝试表明，光感受器马赛克的奈奎斯特频率，即空间分辨率的理论上限，与测量结果一致。
The spatial contrast transfer function of the visual system of the pigeon was determined by recording from the optic tectum evoked potentials or extracellular unit activity in response to a pattern stimulus contrast transfer function, determined as a "response function", describes the relationship between the contrast in the pattern--which consisted of vertically oriented stripes of sinusoidally varying luminance--and the amplitude of the response at various spatial frequencies (c/deg). The transfer function yields an estimate of the high frequency limit, which in turn is a measure of visual resolving power. Action potentials were recorded extracellularly using glass microelectrodes; for evoked potentials, stainless steel electrodes were used. Recordings were made from the stratum griseum et fibrosum superficiale of the optic tectum. The highest spatial frequency detectable in a visual system is limited by various factors, including the diffraction of light at the pupil and the anatomical spacing of the photoreceptors. The pupil factor can be controlled in experiments in a suitable way. In this paper, the electrophysiologically determined high-frequency limit was compared with the theoretical resolution limit imposed by the photoreceptor mosaic. The experimental results show that the visual system of the pigeon has a high-frequency limit at a spatial frequency of 15.5 c/deg, corresponding to a visual acuity of 1.9 min of arc. The attempt to relate visual acuity in the pigeon to the anatomical spacing of the photoreceptors shows that the Nyquist frequency of the photoreceptor mosaic, the theoretical upper bound of the spatial resolution, agrees with measurement.