Olfactory bulb responses after odor aversion learning by young rats.

The increased olfactory bulb response by young rats to familiar odors was not observed in response to odors which have attained their familiarity in aversive situations. Odor experience associated with toxicosis induced a behavioral aversion to the odor which was not accompanied by the enhanced uptake of [14C]2-deoxyglucose (2-DG) that accompanies attractive familiar odors. A single odor exposure on day 17 was sufficient to induce a small increase in 2-DG uptake in specific glomerular areas. We hypothesize that a different neural substrate underlies familiarity associated with an aversive odor than that associated with an attractive odor.