Medial or lateral orbitofrontal cortex activation during fear extinction differentially regulates fear renewal

Abstract

Some anxiety-related disorders, such as panic disorder, specific phobia, post-traumatic stress disorder (PTSD), and obsessive-compulsive disorder (OCD), develop because of the poor regulation and inappropriate expression of fear-related behavior at the wrong place and wrong time. In clinical settings, exposure therapy, which consists of repeated presentation of trauma-related stimuli without real threats in the therapeutic context, is commonly used to treat these disorders. However, 30-50 % of patients suffer from the recurrence of anxiety symptoms after they leave the therapeutic context. This behavioral phenomenon is called renewal. In this study, ABA Pavlovian fear renewal paradigm was used to assess the role of the aberrant orbitofrontal cortex (OFC) activation, a symptom of OCD patients, on fear regulation in laboratory settings. The rats were fear conditioned in one context (context A), extinguished to the tones in another context (context B), and then tested in either context A or B. During extinction, rats were subjected to lateral or medial OFC activation. We found that rats that underwent extinction with either lateral or medial OFC activation were unable to use the context to determine whether it was a safe or dangerous context during renewal test. Interestingly, the rats with lateral OFC activation during extinction showed generally high fear, whereas the rats with medial OFC activation during extinction showed generally low fear. In conclusion, our results suggested that aberrant activation of specifically the lateral OFC may have a negative impact during exposure therapy treatments and results in their poor regulation of fear-related behavior.

Keywords: Exposure therapy; Fear renewal; Obsessive-compulsive disorder; Orbitofrontal cortex; Rat.