Schedule-Induced Polydipsia Task

Schedule-Induced Polydipsia (SIP) is an operant model used to assess compulsive behavior, habit formation, and behavioral inflexibility. Animals develop excessive, non-homeostatic drinking behavior in response to intermittent reward schedules, providing a sensitive measure of repetitive and compulsive actions that share similarities with behavioral domains affected in disorders such as obsessive-compulsive disorder (OCD), schizophrenia, and substance use disorders. Rather than modeling a single clinical test, SIP captures core dimensions of compulsivity and excessive habit-driven behavior that are highly relevant across multiple psychiatric conditions.

In this assay, animals can be stratified into high- and low-compulsive phenotypes based on their drinking behavior, enabling the investigation of treatment effects within disease-relevant endophenotypes and increasing sensitivity for detecting subtle pharmacological effects. Moreover, SIP demonstrates sensitivity to clinically effective anti-compulsive treatments, including the SSRI citalopram, a first-line therapy for OCD. This pharmacological responsiveness supports the assay’s translational validity and its utility for evaluating novel therapeutics targeting compulsive behavior and dysfunctional habit formation.