Conditioned response incidence (mean±SEM) in the experimental (TTX) and control (PBS) groups during acquisition phases, retention and functional tests. The TTX group did not exhibit CRs in Acquisition phase I due to BC inactivation by TTX, whereas the control (PBS) group gradually acquired CRs to asymptotic levels. In the retention test, the TTX group had a very low incidence of CRs compared to the control group, indicating that essentially no learning occurred during inactivation. The TTX group achieved an asymptotic level during Acquisition phase II without BC inactivation. Before the TTX injection test (Pre), both groups exhibited over 90% CRs; after the injection (Post), CR incidence was dramatically reduced in both groups, indicating that injections during Acquisition Phase I were made to eyeblink-related parts of the BC. Compared to TTX, muscimol had a negligible effect on CR incidence. Sessions 1 through 6 are consecutive days of each respective phase of the experiment.