Schedule-dependent production of stereotyped sequences of actions

Abstract

AbstractConcatenating actions into automatic routines is evolutionarily advantageous as it allows organisms to efficiently use time and energy under predictable conditions. However, over reliance on inflexible behaviors can be life-threatening in a changing environment and can become pathological in disease states such as obsessive-compulsive disorder (OCD) and substance use disorder (SUD). Understanding the conditions under which stereotypical sequences of actions are produced is crucial to studying how these behaviors can become maladaptive. Here, we investigated the ability of operant conditioning schedules and contingencies to promote reproducible sequences of five lever presses. We found that signaling reinforcer delivery with a visual cue was effective at increasing learning rates but resulted in mice pressing the lever in fast succession until the cue turned on, rather than pressing it five times. We also found that requiring mice to collect their reinforcer between sequences had little effect on both rate of behavior and on quantitative metrics of reproducibility such as interresponse interval (IRI) variance, and that a training strategy that directly reinforced sequences with low variance IRIs was not more effective than a traditional fixed ratio schedule at promoting reproducible action execution. Together, our findings provide insights into the parameters of behavioral training that promote reproducible sequences and serve as a roadmap to investigating the neural substrates of automatic behaviors.