Both medial prefrontal and amygdala central nucleus lesions abolish heart rate classical conditioning, but only prefrontal lesions impair reversal ofeyeblink differential conditioning

Rabbits with lesions of either medial prefrontal cortex (mPFC) or amygdala central nucleus (ACN) were compared with sham-lesioned animals during diffe rential and reversal classical conditioning of the eyeblink (EB) and heart rate (HR) response. Lesions of the mPFC, but not ACN, produced a severe imp airment in EB reversal conditioning, but neither lesion affected original d iscrimination. However, both mPFC and ACN lesions produced a severe attenua tion of accompanying HR decelerations during both initial differentiation a nd reversal. These results suggest that mPFC processing of Pavlovian condit ioning contingencies affects not only the autonomic component of learning b ut preservative somatomotor conditioning as well, whereas ACN processing af fects only the autonomic component. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.