Bar press durations as a reliable and robust measure of frustration-related operant behavior: Sensitivity to incentive downshift and dose-response paradigms.

In humans, frustrating experiences are known to trigger relapse events and individuals with higher frustration intolerance show increased risk of developing substance use disorders (SUDs). Despite this clear relationship, frustration-related behavior is seldom studied concurrently with self-administration behavior in rodent models. A major obstacle has been the lack of robust, quantitative assays of frustration-related operant behavior thus far. In previous work, we identified increased bar press (BP) durations in response to frustrating conditions in rats self-administering natural or drug rewards. Here, to propose BP durations as a measure of frustration-related behavior, we conducted an operant successive negative contrast (oSNC) study and found that increases in BP durations are observed in the absence of increased effort, providing evidence that this is a psychological phenomenon. Moreover, we assess the viability of widespread use of BP duration measurements as a behavioral tool by quantifying performance as it pertains to sensitivity, robustness, replicability, and sex differences. We conclude that increases in BP durations are a highly sensitive psychological response to frustrating conditions and that this measure is robust, replicable, and applicable to both sexes.

Lever-press duration as a measure of frustration in sucrose and drug reinforcement.

RATIONALE: Currently there is little research into the role of frustration in substance use disorders despite research showing that frustration tolerance in humans is associated with a lower likelihood of developing substance use problems, better outcomes in recovery, and fewer relapses. OBJECTIVE: In order to address this need, our studies use a rat model to focus on frustration-related behavior in natural reward and addiction-related behavioral procedures. Frustration is defined as when a subject is unable to achieve a reinforcer, receives less of a reinforcer than anticipated, or has to work harder to achieve a reinforcer. RESULTS: In these studies, bar-press durations increase when rats are in a state of frustration during self-administration of sucrose, fentanyl, or cocaine. CONCLUSIONS: These data also show that average bar-press durations do not correlate with the number of bar presses, meaning that press duration is an independent measurement that represents a behavioral construct distinct from craving, which is typically measured with number of bar presses. Essentially, these results support that bar press durations can be used as a real-time measure of frustration as a 4th major facet of addiction-related behavior, adding to craving, impulsivity, and habit.