Differential Reinforcement of Low Rates Task

Differential Reinforcement of Low Rates (DRL) is an operant assay used to assess impulsive action, behavioral inhibition, timing, and response control. Animals must withhold responding for a defined period before making a response to obtain a reward, providing a direct measure of their ability to inhibit premature actions. Because successful performance requires both behavioral restraint and precise timing, DRL is particularly valuable for evaluating impulsivity-related deficits relevant to disorders such as ADHD, addiction, OCD, bipolar disorder, schizophrenia, and other neuropsychiatric conditions.

Importantly, DRL provides a translational measure of inhibitory control that aligns with cognitive domains assessed clinically in patients. The task is highly sensitive to pharmacological manipulation and can detect both impairments and improvements in impulse control, making it a powerful tool for evaluating the efficacy of novel CNS therapeutics. The DRL assay is sensitive to atomoxetine, a clinically approved treatment for ADHD, supporting its translational validity as a platform for assessing impulsive action and behavioral inhibition.

Separate groups of adult rats were trained to stable performance levels in the DRL24s task and a signaled Go-NoGo successive discrimination task. In the DRL24s task, vehicle treated rats had peak responding around 24s consistent with accurate temporal discrimination. Dizocilpine (0.03mg/kg s.c.) produced a leftward shift in this response curve. In the Go-NoGo task, in vehicle treated animals, >90% responding was made during the S+ (i.e., Go) phase. Dizocilpine (0.03-0.06mg/kg s.c.) increased responding during the S- (i.e., NoGo) phase, such that only ~75% responding was during the S+ phase. Both tests highlight deficiencies in response control of rats following dizocilpine treatment.