The effect of dopamine on the response to pattern stimulation--study of the chick ERG

The effect of dopamine (DA) on the chick ERG was studied to evaluate its action on the on and off pathways and on the contrast mechanism with regard to background intensity. After intravitreal injection of DA, the b-wave, one component of the on response, was reduced with stimulus intensities lower than background intensity and enhanced with stimulus intensities that were higher. While the d-wave, one of the off responses, was enhanced with stimulus intensities higher than background intensity but not reduced with stimulus intensities that were lower. The pattern ERG amplitude was decreased at higher spatial frequencies. These results suggest that DA has different effects on the on and the off pathways as a function of the adaptive state and could affect the contrast mechanism.