Influence of Nutritional Deprivations in Early Life on Learning Behavior of Rats as Measured by Performance in a Water Maze

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Abstract
Learning behavior was studied in rats that were subjected to different forms of nutritional deprivation in early life. Food deprivation during the first 3 weeks of life was achieved by increasing the number of rat pups nursing from one lactating female. At 3 weeks of age rats were weaned and some were fed an extremely low protein diet for 8 weeks. Four treatment groups were established by subjecting rats to either of these nutritional deprivations alone or by combining the 2 forms of restriction or by providing optimal nutrition from birth. When the rats were from 6 to 9 months of age, visual discrimination performance in a Y water maze was measured. Male rats that were deprived both before and after weaning made significantly more errors than the normal controls. The animals that were deprived pre-weaning or post-weaning alone gave intermediate results. No significant differences were obtained among female rats subjected to the same treatment regimens. The conclusion has been drawn that nutritional deprivation in early life can cause a long-lasting, possibly permanent retardation in the development of learning behavior. Motivational or emotional behavioral differences were noted among the treatment groups and therefore the relative contribution of “drive” as contrasted with “capacity” in the altered learning behavior is not known. When rats were tested for position reversal performance in the water maze shortly after weaning and during the time that certain groups were receiving the severely protein-deficient diet, the most errors were made by the double-deprived rats, followed closely by those that were malnourished only after weaning. Rats that had been restricted prior to weaning only or the normal controls made the fewest errors. Female rats showed a less definite effect of dietary treatment on performance than the males.