Alteration of the visual evoked potential and the electroretinogram in lead-treated monkeys

Rhesus monkeys were pre- and postnatally exposed to either 0, 350, or 600 ppm lead acetate in lab chow. At the age of 7-7 1/4 years visual evoked potentials (VEP) and electroretinograms (ERG) were recorded. Flashes were used as stimuli. The VEP was taken under two background illuminance conditions. Lead-related decreases in amplitudes and increases in latencies were observed. Effects on amplitudes were more pronounced under the dark condition while latencies were more affected at the bright background level. The ERG was studied during the course of dark adaptation. The increase in amplitudes of the b-wave during the adaptation period was more prominent in lead-exposed subjects than in controls. Oscillatory potentials were not altered by lead. The findings are discussed in terms of the physiological mechanisms underlying these different potentials.