Choline supplementation during prenatal development reduces proactive interference in spatial memory

Previous research has demonstrated that increasing dietary choline during early development can have long-lasting effects on cholinergic (Ch) function that are correlated with improvement of spatial memory ability in rats. The present study is designed to further our understanding of these organizational changes in brain and behavior by examining the effects of spaced vs. massed trials. A third of the rats (n=10) were supplemented with choline chloride prenatally by adding it to the drinking water of their dams. Another third were made deficient of choline during early development by removing choline from the dams diet. The remaining rats served as untreated controls. Postnatally, the offspring were maintained on a choline-sufficient diet and at 120 days of age they began 12-arm radial maze training. The maze data revealed two major effects of early choline availability: (1) Both choline-supplemented and choline-deficient rats performed more accurately than control littermates when trials were spaced. These differences in spatial ability did not appear to be a function of differential response or cue-use strategies. (2) Choline-supplemented rats showed little proactive interference when trials were massed; whereas control rats demonstrated moderate levels and choline-deficient rats exhibited high levels of proactive interference as a function of massed trials. These data suggest that the behavioral consequences of early dietary availability of choline may involve the modification of the discriminative abilities used to attend to stimuli that demarcate the end of one trial and the start of another as well as the capacity for remembering the locations that have been visited during a trial.