Testing strategies in behavioral teratology: II. Discrimination learning.

Male and female Wistar rats exposed to methylmercury chloride prenatally via drinking water (1.5 and 5.0 mg/l) were tested in a microcomputer-directed learning task (visual discrimination reversal) at the age of two months. Differences were observed between control and high dose group for several parameters, the most obvious being an increase in passiveness and in response latency, as well as a decrease in intertrial interval response rates in the methylmercury group. No effects were seen in the low dose group. Performances of male and female animals were quite similar. However, females showed longer response latencies and passiveness scores were somewhat higher than in males.