Wright M J, Johnston A
Vision Res. 1982;22(11):1389-99. doi: 10.1016/0042-6989(82)90229-2.
Visual evoked potentials (VEP's) were obtained to grating stimuli modulated in phase at 8 Hz. The amplitude of the VEP was linearly related to the length of a centrally-fixated grating up to a critical length value equivalent to 9-16 grating cycles, for a range of spatial frequencies; thereafter amplitude first decreased then increased with increasing length. VEP amplitude was proportional to log. contrast as well as to length, and the intercept of the regression line with the contrast axis coincided with the psychophysical threshold for gratings of different lengths. More sensitive measurements with low-contrast stimuli around threshold indicated that in this range VEP amplitude is linearly related to contrast, and there is no threshold nonlinearity. The effects of visual field location and adaptation on the VEP to gratings of different lengths and spatial frequencies were also studied. The relationship of these findings to psychophysical, single-cell and transient VEP data is discussed.
对以8赫兹同相调制的光栅刺激记录视觉诱发电位（VEP）。对于一系列空间频率，VEP的振幅与中央注视光栅的长度呈线性关系，直至达到相当于9 - 16个光栅周期的临界长度值；此后，振幅随长度增加先减小后增大。VEP振幅与对数对比度以及长度成正比，回归线与对比度轴的截距与不同长度光栅的心理物理学阈值一致。在阈值附近使用低对比度刺激进行更灵敏的测量表明，在此范围内VEP振幅与对比度呈线性关系，且不存在阈值非线性。还研究了视野位置和适应对不同长度和空间频率光栅VEP的影响。讨论了这些发现与心理物理学、单细胞和瞬态VEP数据的关系。
