Fear conditioning. Effects of donepezil pre-treatment and 192-IgG-saporin (Sap) lesions on percentage of freezing and total number of 22-kHz fear-associated ultrasonic vocalizations (USVs) during fear conditioning (FC) training (a), context (CN) test (b) and tone (TN) test (c). All animals acquired a clear freezing response during FC training and showed mnesic retention of the conditioned freezing response during CN and TN tests. USVs were nearly totally suppressed in saline-treated Sap-lesioned rats, and donepezil pre-treatment tended to increase USV production in donepezil-treated Sap-lesioned rats during FC training. BS, Baseline; Don-Sham, donepezil-treated sham-lesioned rats; ITI, Inter-trial interval; Sal-Sham, Saline-treated sham-lesioned rats. All groups: ****P < 0.00001; Sal-Sham vs. Sal-Sap: #P < 0.05.