Freezing during sequential extinction and retrieval+extinction, LTM, and reinstatement tests when compound CS consists of matched intensity blinking light and 70-dB tone. Rats were fear conditioned to a matched intensity 70T+BL compound, and underwent either ret+ext with the 70-dB tone followed 3 h later by ret+ext of the blinking light (70T first ret+ext, n = 8), ret+ext with the blinking light first followed 3 h later by ret+ext of the 70-dB tone (BL first ret+ext, n = 14), ext-only with the 70-dB tone followed 3 h later by ext-only of the blinking light (BL first ext-only, n = 8), ext-only with the blinking light first followed 3 h later by ext-only of the 70-dB tone (70T first ext-only, n = 14), or remained in their home cages (no ext, n = 15). Ret+ext of the 70-dB tone component reduced freezing to the blinking light during the second ret+ext compared to ext-only (P = 0.048). All forms of sequential extinction with individual cues matched on saliency resulted in a significant decrease in freezing to the compound 24 h after extinction or retrieval+extinction compared to no ext (ext-only 70-dB tone first, P = 0.03; all other P’s < 0.001). There was no reinstatement of freezing to the compound for any of the extinction groups (all P’s > 0.05) when compared to their freezing during LTM and all forms of sequential ext-only or ret ext resulted in a significant decrease in freezing to the compound compared to the no ext groups (P < 0.01). Additionally, both forms of ret+ext and ext-only with the blinking light first significantly reduced freezing during tests for reinstatement to the compound compared to ext-only with the tone first (all P’s < 0.05). The tone only reinstatement test revealed that all forms of extinction or retrieval+extinction reduced freezing to the tone compared to the no extinction group (all P’s < 0.001) with the exception of the tone first ext-only (P = 0.322). Ret+ext with the tone first significantly reduced freezing to the tone during reinstatement tests compared to ext-only with the tone first (P = 0.047). All extinction groups showed reduced freezing to the blinking light test for reinstatement (all P’s < 0.05).
