Thompson D A, Drasdo N
Vision Sciences, Aston University, Birmingham, UK.
Doc Ophthalmol. 1987 Jun;66(3):233-44. doi: 10.1007/BF00145237.
Pattern onset electroretinograms (PERGs) were recorded from four normal subjects. Square-wave gratings of 75% contrast were presented in three approximately contiguous, concentric zones of outer angular radius, 5.1 degrees, 12.6 degrees, and 23.6 degrees. The zones were calculated to give equal numbers of ganglion cell receptive fields. The recorded PERGs were considered to include luminance and pattern components which have low and bandpass spatial tuning functions respectively. These components combine in the PERG to produce a broad spatial tuning characteristic. The amplitude of PERGs in response to low spatial frequency stimuli is widely reported to be linearly related to contrast. The retinal illuminance response at every spatial frequency was computed from the eye's modulation transfer function. This function characterizes the reduction in contrast that occurs because of optical degradation. The computed retinal illuminance response was subtracted from the PERG waveform and a pattern-specific response was revealed. The latter had a highly tuned bandpass function which peaked at higher spatial frequencies than the PERG at corresponding peripheral angles.
对四名正常受试者记录了图形起始视网膜电图（PERG）。呈现75%对比度的方形波光栅，位于三个近似连续的、外视角半径分别为5.1度、12.6度和23.6度的同心区域。计算这些区域以使神经节细胞感受野数量相等。记录的PERG被认为包括分别具有低空间调谐函数和带通空间调谐函数的亮度和图形成分。这些成分在PERG中结合以产生广泛的空间调谐特性。广泛报道，对低空间频率刺激的PERG振幅与对比度呈线性相关。根据眼睛的调制传递函数计算每个空间频率下的视网膜照度响应。该函数表征了由于光学退化而导致的对比度降低。从PERG波形中减去计算出的视网膜照度响应，从而揭示出特定于图形的响应。后者具有高度调谐的带通函数，其峰值出现在比相应周边角度处的PERG更高的空间频率处。
