Elevation of prefrontal acetylcholine is related to the extinction of learned behavior in rats.

To investigate whether changes occur in acetylcholine (ACh) levels in the rat medial prefrontal cortex (mPFC) during initial lever-press extinction training, in vivo microdialysis was used to measure mPFC ACh. Elevated ACh was found during this training period. Furthermore, this elevation significantly correlated with the number of responses found in the re-training session the next day, but not with that in the initial training. These results suggest that the mPFC ACh elevation during the initial training period enhances the progress of lever-press extinction across sessions.