SPATIAL-FREQUENCY TUNING OF THE MONKEY PATTERN ERG DEPENDS ON D2 RECEPTOR-LINKED ACTION OF DOPAMINE

The pattern electroretinogram (PERG) has been previously shown to be s ensitive to dopaminergic manipulations in the monkey's retina. In orde r to study the role of retinal D2 receptors we recorded the PERG befor e and during the acute administration of l-sulpiride, a selective D2 b locker, in three monkeys. The stimuli were sinusoidal vertical grating s, with a contrast of 70%, counterphase modulated at 7.5 Hz. The respo nse to four different spatial frequencies (0.5, 1.1, 2.3 and 4.6 c/deg ) was explored. PERGs were recorded before and after 20 min of i.m. ad ministration of E-sulpiride. Two different doses (0.07 and 0.35 mg/kg) were administered in different sessions for each spatial frequency (S F). Baseline (before sulpiride) responses showed high intersession rep roducibility, with a clear SF tuning. Both doses of the drug affected the PERG to the peak SF of the stimulus, but the higher one was more c onsistently effective in all of the three monkeys. Our results confirm previous studies which suggested that DA is involved in retinal proce ssing in the primate and reveal the new information that D2 receptors are necessary for spatio-temporal tuning of pattern vision.