Plant G T, Hess R F
Brain. 1985 Sep;108 ( Pt 3):647-76. doi: 10.1093/brain/108.3.647.
The temporal contrast sensitivity function and temporal frequency discrimination have been studied in normals and in 7 cases of multiple sclerosis or optic neuritis. Sinusoidal gratings of two spatial frequencies (0.2 and 2.0 cycles/deg) were used. The abnormalities demonstrated in the patients varied between individuals but overall a picture has emerged of four principal anomalies. The temporal transfer function of the 2 cycles/deg medium spatial frequency grating has a band-pass appearance, whereas it is low-pass in normal subjects (5 out of 8 eyes). The peak of temporal frequency discrimination function (i.e. the temporal frequency at which discrimination is most acute) occurs at a lower temporal frequency in the patients than in normal subjects particularly at the higher spatial frequency (5 out of 8 eyes for a spatial frequency of 2.0 cycles/deg; 2 out of 8 eyes for a spatial frequency of 0.2 cycles/deg). It was found that normal subjects were able to discriminate between the maximum temporal frequency used as a standard in the discrimination experiments (16 Hz) and a higher temporal frequency. In the patients, however, a cut-off in the discrimination function occurred at a temporal frequency well below this (8 out of 8 eyes for a spatial frequency of 2.0 cycles/deg; 2 out of 8 eyes for a spatial frequency of 0.2 cycles/deg). Further to the above result, in a number of patients an attempt was made to ascertain how the gratings were perceived in this abnormally extensive region of ambiguity in the high temporal frequency range. It was found that high temporal frequencies, at a constant contrast level above threshold and constant apparent contrast, were perceived either as flickering at a slower rate than did an intermediate temporal frequency or even appeared stationary. This effect was rare at the lower spatial frequency (1 out of 8 eyes) but was demonstrated in 4 out of 8 eyes at the spatial frequency of 2.0 cycles/deg. It was not specifically sought in all individuals. These results are discussed in the context of an information channelling model of temporal frequency processing in the visual system.
对正常人和7例多发性硬化症或视神经炎患者的时间对比敏感度函数和时间频率辨别能力进行了研究。使用了两种空间频率（0.2和2.0周/度）的正弦光栅。患者表现出的异常情况因人而异，但总体上出现了四种主要异常情况。2周/度中等空间频率光栅的时间传递函数呈带通外观，而在正常受试者中（8只眼中的5只）它是低通的。时间频率辨别函数的峰值（即辨别最敏锐的时间频率）在患者中出现在比正常受试者更低的时间频率处，尤其是在较高空间频率时（对于2.0周/度的空间频率，8只眼中的5只；对于0.2周/度的空间频率，8只眼中的2只）。研究发现，正常受试者能够区分辨别实验中用作标准的最大时间频率（16赫兹）和更高的时间频率。然而，在患者中，辨别函数在远低于此的时间频率处出现截止（对于2.0周/度的空间频率，8只眼中的8只；对于0.2周/度的空间频率，8只眼中的2只）。除上述结果外，还对一些患者进行了尝试，以确定在高时间频率范围内这个异常广泛的模糊区域中光栅是如何被感知的。研究发现，在高于阈值的恒定对比度水平和恒定表观对比度下，高时间频率要么被感知为比中间时间频率闪烁得更慢，要么甚至看起来是静止的。这种效应在较低空间频率时很少见（8只眼中的1只），但在2.0周/度的空间频率时，8只眼中的4只出现了这种情况。并非对所有个体都专门进行了此项研究。在视觉系统中时间频率处理的信息通道模型的背景下对这些结果进行了讨论。
