Involvement of the olfactory bulb in consolidation processes associated with long-term memory in rats

In a daily training paradigm, rats were trained to discriminate between spatially distinct electrical stimulations delivered to one olfactory bulb. Xylocaine injections were used to disrupt the olfactory bulb functioning in the region close to the electrode tips for 1 hr after training session. The treatment started either just after the session or 2 hr later. When compared with the performance of saline-injected rats, the performance of Xylocaine-injected rats was unimpaired except when the treatment started just after the daily session. In that case, acquisition of the task was slightly altered, and retention over a 5-day period was dramatically impaired. We therefore concluded that, within about 1 hr following training, the olfactory bulb is engaged in consolidation processes critical for long-term retention of learned olfactory cues.