Probing the habitual and compulsive-like basis of (dys)functional checking in the Observing Response Task, a rodent...

Excessive and maladaptive checking is a prominent symptom of obsessive-compulsive disorder (OCD). This dysfunctional checking can be modelled using the Observing Response Task (ORT), which distinguishes between functional and dysfunctional checking shown by the same individuals, in rodents and humans. We have previously observed that rats classified as sign-trackers on a pavlovian autoshaping procedure show elevated levels of dysfunctional checking.

We sought to determine whether dysfunctional checking was habitual and compulsive.

119 Lister Hooded rats (M = 95, F = 24) were classified using pavlovian autoshaping and concurrently underwent ORT training. Briefly, rats learned to respond on one of two levers to receive reinforcement, with the correct lever changing unpredictably throughout the session. Pressing a third, 'observing' lever illuminated a light cue over the currently correct lever. These functional Observing Lever Presses (OLPs) can be distinguished from dysfunctional Extra Observing Lever Presses (eOLPs), which have no programmed consequences. Whether dysfunctional checking was habitual was examined by degrading the contingency between checking and light cue presentation, and whether it was compulsive was determined by punishing 50% of checking responses.

Sign-trackers showed higher levels of dysfunctional checking than goal-trackers and intermediates, including after contingency degradation. Punished checking eradicated checking behaviour in most rats, but a minority of sign-trackers persisted despite punishment via shock.

These data support the hypothesis that sign-trackers exhibit more cue-driven checking behaviour than goal-trackers. Observations from punished checking refer to the prevalence of severe OCD in the human population concerning persistence of pathological checking despite aversive consequences.