Role Of The Auditory Cortex In The Acquisition And Extinction Of Differential Bradycardiac Conditioning To Tonal Stimuli In Rabbits

In Experiment 1, rabbits with either auditory (AC) or visual cortex (VC) lesions received 7 days of differential Pavlovian bradycardiac conditioning. All animals demonstrated differential conditioning during the first 3 days of conditioning; however, on days 4-7, AC lesioned animals did not exhibit significant differential bradycardiac conditioning due to an enhanced response magnitude to the unpaired tone (CS$-).$ This study indicates that the AC plays a role in the acquisition of differential bradycardiac conditioning to tonal stimuli. In Experiment 2, AC or VC lesioned animals received 2 days of differential bradycardiac conditioning followed by 7 days of extinction. Whereas the bradycardiac responses quickly extinguished in the VC lesioned group, the AC lesioned group continued to exhibit significantly larger bradycardiac responses to the paired stimulus (CS+) relative to the CS$-$ during all 7 days of extinction. These data provide evidence that the AC is involved in the extinction of differential bradycardiac conditioning to tonal stimuli. The findings of these experiments suggest that the AC is involved in the inhibition of non-reinforced stimuli during differential bradycardiac conditioning to tonal stimuli