ERG assessment of zebrafish retinal development

Research has shown that adult zebrafish have a complex visual system, with two possible opponent mechanisms. Anatomically, zebrafish retina develops i n a sequential manner and is immature at hatching. The purpose of the prese nt study was to assess zebrafish retinal development using the electroretin ogram (ERG). ERG responses to visual stimuli were obtained from 4-5, 6-8, 1 3-15, and 21-24 days postfertilization (dpf) zebrafish. Individual waveform s were assessed and compared across the four age groups. Spectral-sensitivi ty functions were calculated far the a- and b-wave components of the ERG re sponse. Results showed that the ERG waveforms and spectral-sensitivity func tions varied with age. While the 21-24 dpf subjects had an ERG waveform tha t was similar to that of adults, the younger subjects did not. Although the re were modest differences in the a-wave spectral sensitivity, substantial differences were found in the b-wave spectral sensitivities across the ages . There was a consistent strong response to ultraviolet wavelengths, while across the remaining parts of the spectrum, there was a gradual increase in sensitivity with age. Also, the 21-24 dpf subjects appear to have adult-li ke U- and S-cone functions, but were missing the L-M and the M-S opponent m echanisms found in the adult. These results support the findings of the ana tomical studies and demonstrate that the zebrafish is a useful model for ex amining the development of retinal function.