Behavioral flexibility in a mouse model for obsessive-compulsive disorder: Impaired Pavlovian reversal learning in SAPAP3 mutants

Abstract

Obsessive-compulsive disorder (OCD) is characterized by obsessive thinking, compulsive behavior and anxiety, and is often accompanied by cognitive deficits. The neuropathology of OCD involves dysregulation of cortical-striatal circuits. Similar to OCD patients, SAPAP3 knockout mice 3 (SAPAP3^-/- ) exhibit compulsive behavior (grooming), anxiety and dysregulated cortical-striatal function. However, it is unknown whether SAPAP3^-/- display cognitive deficits and how these different behavioral traits relate to one another. SAPAP3^-/- and wild-type (WT) littermates were trained in a Pavlovian conditioning task pairing visual cues with the delivery of sucrose solution. After mice learned to discriminate between a reward-predicting conditioned stimulus (CS+) and a non-reward stimulus (CS-), contingencies were reversed (CS+ became CS- and vice versa). Additionally, we assessed grooming, anxiety and general activity. SAPAP3^-/- acquired Pavlovian approach behavior similarly to WT, albeit less vigorously and with a different strategy. However, unlike WT, SAPAP3^-/- were unable to adapt their behavior after contingency reversal, exemplified by a lack of re-establishing CS+ approach behavior (sign tracking). Surprisingly, such behavioral inflexibility, decreased vigor, compulsive grooming and anxiety were unrelated. This study shows that SAPAP3^-/- are capable of Pavlovian learning, but lack flexibility to adapt associated conditioned approach behavior. Thus, SAPAP3^-/- not only display compulsive-like behavior and anxiety, but also cognitive deficits, confirming and extending the validity of SAPAP3^-/- as a suitable model for the study of OCD. The observation that compulsive-like behavior, anxiety and behavioral inflexibility were unrelated suggests a non-causal relationship between these traits and may be of clinical relevance for the treatment of OCD.

Keywords: Pavlovian conditioning; SAPAP3 mutant mice; anxiety; behavioral flexibility; cognitive flexibility; compulsive behavior; general activity; obsessive-compulsive disorder; reversal learning; symptoms relationship.