PRENATAL PROTEIN-MALNUTRITION IMPAIRS VISUAL-DISCRIMINATION LEARNING IN ADULT-RATS

Developing rats were either malnourished or adequately nourished during the prenatal period by feeding their dams diets containing low (6% casein) or adequate (25% casein) amounts of protein for 5 weeks prior to mating and throughout pregnancy. All pups received adequate nutrition from the day of birth onwards. Male offspring were tested on the Lashley jump stand in three visual discrimination problems, beginning at 91 days of age. The previously malnourished rats made significantly more errors overall and took significantly longer to learn the three discrimination problems than did the controls. This was due primarily to inferior performance on a vertical-versus horizontal-stripe discrimination task. No significant difference between the two groups was found in brightness discrimination or in the discrimination of a square and a circle. Our results are consistent with the view that malnutrition and its associated stresses during prenatal life significantly disrupt later performance of certain complex visual learning tests.