Perirhinal cortex inactivation produces retrieval deficits in fear extinction to a discontinuous visual stimulus.

Several studies suggest that the perirhinal cortex (PER) may function to unitize stimulus components across time or modalities. While the PER has been shown to be critical for fear acquisition to discontinuous stimuli, the role of the PER in fear extinction memory has not been evaluated. The current study assessed the involvement of the PER during fear extinction training to a continuous or discontinuous conditioned stimulus (CS). Rats were randomly assigned to 1 of 4 groups based on 2 factors: the CS type (a continuous or discontinuous light) and a pretesting PER manipulation (muscimol inactivation or saline). Results showed that PER inactivation impaired fear memory to both CS types; however, PER inactivation had only impaired extinction memory to the discontinuous light. These results suggest the role of the PER in stimulus unitization extends to supporting the acquisition of fear extinction memory. (PsycINFO Database Record (c) 2020 APA, all rights reserved).