The effects of embryonic exposure to alcohol on learning and inhibition in chicks

The effects of embryonic exposure to ethanol on visual (hue) discrimination learning, conditioned inhibition and transfer of inhibition were examined in White Leghorn chicks. Injections of ethanol (low vs high dose) or saline (low vs high volume) into the air space of the egg were given for 5 consecutive days over Days 1-5, 6-10 or 11-15 of the 21-day incubation period. Tests of learning ability began 4 days after hatching and involved autoshaped keypecking in Pavlovian paradigms with food reinforcement. Treatment with alcohol early in incubation (Days 1-5) disrupted both the learning and transfer of conditioned inhibition. Moreover, a high injection volume, per se, suppressed responding to all stimuli. Treatment with alcohol during either the first or second 5 days of incubation selectively affected responding to a red stimulus, but not to a green or yellow stimulus. Birds treated between Days 1-5 of incubation generally showed greater disruption than those treated later. We conclude that the chick provides a viable model for studying the behavioral consequences of prenatal exposure to alcohol.