Figure 1.
Electroretinograms (ERGs) (Experiment 1).
Panel A. Dark-Adapted Flash ERG Waveforms. Waveforms are presented from a representative control rat (0 ppm PTU) recorded from a sequence of flashed stimuli that progressed from very dim to bright. The a-wave and b-wave are indicated. The response reflects primarily rod photoreceptors (a-wave) and retinal on-bipolar cells (b-wave). The response components grew systematically in amplitude and decreased in latency with increasing flash illumination.
Panel B. Group mean (± SE) dark-adapted ERG a-wave amplitudes, as a function of flash intensity. Adult offspring were previously treated with either 0 or 3 ppm PTU in drinking water from GD2-PN21. The a-wave amplitudes were significantly increased in amplitude by PTU treatment.
Panel C. UV-Flicker ERGs group mean waveforms. ERGs were recorded from light-adapted rats to a UV stimulus flickering at 21 Hz against a steady green background to isolate responses of S-cone photoreceptors. Group average responses to three levels of UV irradiance are shown for rats exposed to 0 or 3 ppm PTU.
Panel D. Mean (± SE) amplitude of the UV-Flicker ERGs as a function of UV stimulus irradiance. Amplitude is expressed as spectral density at 21 Hz, as derived from spectral analysis of the individual rat waveforms. There were no statistically significant effects of PTU treatment on UV ERG response amplitude.
Panel E. Green-Flicker ERGs group mean waveforms. ERGs were recorded from light-adapted rats to a green light flickering at 21 Hz against a steady UV background to isolate responses of M-cone photoreceptors. Group average responses to four levels of luminance are shown for rats exposed to 0 or 3 ppm PTU.
Panel F. Mean (± SE) amplitude of the Green Flicker ERGs as a function of green flicker stimulus luminance on a log scale. Amplitude is expressed as spectral density at 21 Hz, as derived from spectral analysis of the individual rat waveforms. There was a statistically significant interaction between PTU treatment and flicker illuminance. Treatment with PTU caused a statistically significant reduction of green-flicker ERG amplitude at the highest value of luminance tested (30 cd*s/m2)