DISSOCIATION OF BEHAVIORAL AND NEURAL CORRELATES OF EARLY ASSOCIATIVELEARNING

Wistar rat pups were trained in an olfactory associative conditioning task on postnatal Day 6, 12, or 20. The training consisted of 20 pairi ngs of a novel odor (peppermint) with footshock (1.5 mA, 1 s) with an intertrial interval of 3 min. Additional pups were trained in either u npaired or naive control conditions. On the day following training, pu ps were either tested for their behavioral response to the conditioned odor in a two-odor choice test, or injected with C-14-2-deoxyglucose and exposed to the odor for examination of olfactory bulb neural respo nses to the odor. The results demonstrate that, although pups at all a ges learned to avoid the odor, only pups trained during the first post natal week had a modified olfactory-bulb glomerular-layer response to the odor. These results suggest that although olfactory memory is corr elated with modification of olfactory bulb glomerular layer function i n newborns, these changes are not required for normal memory in older pups. (C) 1995 by John Wiley & Sons, Inc.