Lever Press Duration as a Measure of Frustration Motivated Response Variation in Rat Self-administration to Investigate the Effects of Frustration on Substance Use Behavior

In human studies, frustration has been identified as a potential risk factor for substance use disorders. 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. To address this need, our studies use rat self-administration models to focus on frustration-related behavior in natural reward and addiction-related behavioral procedures. First, to study frustration in operant responding, there is a need to establish a real-time objective measure and validate its use in predicting vulnerability to drug use. Frustration is when a subject cannot achieve a reinforcer, receives less than the anticipated reinforcer, or has to work harder to achieve a reinforcer. Therefore, the measure of frustration should increase in instances consistent with the definition of frustration. Furthermore, the operant measure of frustration should assess a form of either the approach or avoidance responses to frustration. Increases in bar press durations are shown to be an approach strategy that can be used to measure frustration-related behavior objectively and, in some conditions, has the potential to signal a future transition to avoidance strategies. Supplementary experiments solidify that changes in bar press durations are a modification of continued approach behavior that can be used to objectively measure frustration-related behavior by satisfying nine behavioral criteria for barpress durations to measure frustration. Additional experiments established the predictive validity of identifying individual differences in frustration-like behavior as measured by bar press durations prior to drug self-administration. This work also affirms bar press durations as the optimal measure of frustration-like behavior within operant self-administration compared to the force of a bar press as a potential alternative approach response variation. Essentially, the results within this dissertation solidify bar press durations as an effective measure of frustration-like behavior to further elucidate the understanding of frustration within substance use disorders.