Systemic haloperidol administration increases the amplitude of the light- and dark-adapted flash ERG in the monkey

1. To examine the effect of dopaminergic blockade on signal processing in the primate retina, both light- and dark-adapted flash electroretinograms (flash ERGs) were measured in 5 normal Cynomolgus monkeys prior to and following the systemic administration of haloperidol, a blocker of dopamine receptors. 2. The stimulus was delivered as a single flash of Intensity 16 (Grass PS2 Photo Stimulator) which subtended 25.8 deg of visual angle. Baseline flash ERGs appeared similar to those recorded in the human. Flash ERG amplitude was measured from the trough of the a-wave to the peak of the b-wave. 3. Following baseline recordings, haloperidol was administered (0.1 mg/kg, i.m.). Haloperidol caused a statistically significant increase in the amplitude of both light- and dark-adapted flash ERGs in all monkeys. 4. In conclusion, dopamine receptor blockade in the primate retina enhances both light and dark adapted flash ERGs, a result which suggests that dopamine is active in both the light and the dark in response to flash stimulation.