Mean CR incidence (±SEM) of BC-targeted (diamonds) and LL-targeted (circles) groups during individual stages of the experiment. While the BC group exhibited a negligible number of CRs during Acquisition Phase I, the LL animals rapidly acquired CRs. During the retention test, the BC group had no CRs, indicating that CRs were not acquired in sessions with the BC inactivated. On the other hand, the LL group exhibited high CR incidence, suggesting that normal CR acquisition occurred in sessions during which TTX was applied to the LL. During Acquisition Phase II, the LL group demonstrated a high frequency of CRs, while the TTX group acquired CRs gradually, as would be expected in animals that did not learn during Acquisition Phase I. D-1 through D-6: consecutive days of corresponding phases of the experiment.