Fig. 3.

Effect of muscimol infusion on differential conditioning. (A, B). Pre-conditioning drug infusion (Exp. 1). (A) No significant effect of drug infusion on discrimination ratio was found (see Results for detail). (B) Freezing levels to the CS+ and CS- during the drug-free retention test showed differential responding regardless of drug condition. (C, D) Pre-testing drug infusion (Exp 2). (C) Muscimol infusion significantly reduced discrimination ratio on the retention test. (D) Freezing levels to the CS+ and CS- during the retention test showed that inhibitory responding to CS- was impaired only in the muscimol infusion group. Data are expressed as mean ± S.E.M. Arrows indicate drug infusion (muscimol or aCSF).