The effects of temporary inactivation of the orbital cortex in the signal attenuation rat model of obsessive compulsive disorder.

Rats undergoing extinction of lever pressing after an external feedback for this behavior was attenuated by extinguishing its Pavlovian association with the reward (signal attenuation) exhibit compulsive lever pressing. The present study tested the effects of temporary inactivation of the orbital cortex in rats undergoing extinction of lever pressing that was or was not preceded by signal attenuation (post-training signal attenuation and regular extinction, respectively). Orbital inactivation led to a nonspecific decrease in lever pressing in rats undergoing post-training signal attenuation and to the emergence of compulsive-like behavior in rats undergoing regular extinction. These results suggest that orbital inactivation and extinguishing a Pavlovian stimulus-reinforcer contingency have a similar effect on lever pressing and are in line with previous findings implicating the orbital cortex in mediating the effects of previously acquired stimulus-reinforcer associations on operant behavior.