Figure 4. Spatial transfer function of pattern electroretinogram (PERG) amplitude (A, B) and latency (C, D) for different mouse strains. All responses have been obtained at a fixed temporal frequency of 1 Hz and contrast of 1.0. In all panels, symbols represent the mean±standard error of the mean. Amplitude and latency changes are expressed in relative units compared to the maximal PERG in response to gratings of 0.05 cycles/degree and contrast of 1.0 reversing at 1 Hz, corresponding waveforms of which are shown in Figure 1.