Barbur J L, Harlow A J, Sahraie A
Applied Vision Research Centre, City University, London, UK.
Ophthalmic Physiol Opt. 1992 Apr;12(2):137-41. doi: 10.1111/j.1475-1313.1992.tb00276.x.
Pupillary responses to stimuli which favour the preferential stimulation of neural mechanisms involved in the detection of visual attributes such as colour, spatial structure, movement and light flux changes on the retina have been measured and compared. Pupil responses to a decrement in stimulus luminance (i.e., a flash of darkness), suggest that at least three components are involved in this response, their relative contribution being determined largely by stimulus size, contrast and presentation time. A comparison of pupil responses to gratings of equal and lower space-averaged luminance shows that the amplitude of pupillary constriction at grating onset for the equal luminance condition is about twice that measured with similar gratings in the lower luminance condition. Pupillary responses to chromatic isoluminant gratings are in general of longer latency when compared to responses of similar amplitude elicited by achromatic gratings. Small pupillary constrictions elicited by the onset of coherent movement in dynamic, random dot patterns are also demonstrated under stimulus conditions which eliminate pupillary responses to sudden light flux changes on the retina. The results support an earlier hypothesis which suggests that the onset of sudden changes in neural activity in the visual cortex when a visual stimulus is presented to the eye causes an overall perturbation which weakens transiently the regulatory inhibitory input to the pupillomotor nucleus. This, in turn, results in a transient increase in the efferent parasympathetic innervation of the iris sphincter muscle and hence the observed constriction of the pupil. The characteristics of the pupillary response reflect the properties of the mechanisms and the number of neurones which participate in the detection of each stimulus attribute.
已经测量并比较了瞳孔对刺激的反应，这些刺激有利于优先刺激参与检测视觉属性（如颜色、空间结构、运动和视网膜上光通量变化）的神经机制。瞳孔对刺激亮度降低（即黑暗闪光）的反应表明，该反应至少涉及三个成分，它们的相对贡献在很大程度上由刺激大小、对比度和呈现时间决定。对具有相等和较低空间平均亮度的光栅的瞳孔反应进行比较表明，在相等亮度条件下，光栅开始时瞳孔收缩的幅度约为在较低亮度条件下用类似光栅测量值的两倍。与由消色差光栅引起的类似幅度的反应相比，瞳孔对彩色等亮度光栅的反应通常具有更长的潜伏期。在消除视网膜上对突然光通量变化的瞳孔反应的刺激条件下，也证明了动态随机点图案中相干运动开始时引起的小瞳孔收缩。这些结果支持了一个早期假设，即当视觉刺激呈现给眼睛时，视觉皮层中神经活动的突然变化会引起整体扰动，从而暂时削弱对瞳孔运动核的调节性抑制输入。反过来，这会导致虹膜括约肌传出副交感神经支配的短暂增加，从而观察到瞳孔收缩。瞳孔反应的特征反映了参与检测每个刺激属性的机制和神经元数量的特性。
