Effects of prenatal nutrition on learning and motivation in rats.

The results of two learning experiments revealed that adult male rats whose dams suffered either prenatal zinc deficiency or undernutrition showed, as compared to rats whose dams were fed ad lib, normal diets during pregnancy (1) more resistance to extinction following partial reinforcement, and (2) a faster occurring negative contrast effect when shifted from large to small reward. An incentive-motivation interpretation of the data suggests that the nutritionally deprived and normal animals differ with respect to the incentive value of the consummatory reward. This effect appears to be long-term.