Perinatal choline supplementation increases the threshold for chunking in spatial memory.

Chunking and perinatal choline supplementation each provide rats with alternative memory processing advantages. Evidence from radial-arm maze performance of adult (2- to 5-month-old) rats indicates that chunking of multiple food types (sunflower seeds, Noyes pellets and rice puffs) emerges for stable, differentiable baiting patterns as a function of the memory load (6, 12, 18 or 24 maze arms). The number of maze arms appeared to determine both the level of task difficulty at which rats began to implement a chunking strategy as well as when they were unable to successfully implement such a strategy due to the excess memorial demands of the task. In comparison to control rats, rats treated perinatally with choline supplementation displayed a horizontal rightward shift of the response function that related level of clustering of like-food types to the number of maze arms. These results indicate a higher threshold for implementing a chunking strategy in rats treated perinatally with choline supplementation, possibly due to a choline-induced increase in memory capacity.