Task parameters influence operant response variability in mice

• Published in: Psychopharmacology Vol. 240; no. 1; pp. 213 - 225
• Main Authors: Follman, Emma G., Chevée, Maxime, Kim, Courtney J., Johnson, Amy R., Tat, Jennifer, Leonard, Michael Z., Calipari, Erin S.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-01-2023; Springer; Springer Nature B.V
• Subjects: Animal behavior; Animal experimentation; Animals; Behavior; Biomedical and Life Sciences; Biomedicine; Conditioning, Operant - physiology; Experiments; Fixed ratio schedule; Hypotheses; Interresponse time; Learning; Methods; Mice; Neurosciences; Operant conditioning; Operant response; Original Investigation; Pharmacology/Toxicology; Psychiatry; Psychological research; Psychopharmacology; Reinforcement; Reinforcement Schedule; Schedules; Sucrose; Time Factors; United States; Learning; Reinforcer; Interresponse times; FR5; Reinforcement schedule; Reward; Fixed ratio; Movement kinematics
• ISSN: 0033-3158; 1432-2072
• DOI: 10.1007/s00213-022-06298-z

Rationale
During operant conditioning, animals associate actions with outcomes. However, patterns and rates of operant responding change over learning, which makes it difficult to distinguish changes in learning from general changes in performance or movement. Thus, understanding how task parameters influence movement execution is essential.
Objectives
To understand how specific operant task parameters influenced the repetition of future operant responses, we investigated the ability of operant conditioning schedules and contingencies to promote reproducible bouts of five lever presses in mice.
Methods
Mice were trained on one of the four operant tasks to test three distinct hypotheses: (1) whether a cue presented concurrently with sucrose delivery influenced the pattern of lever pressing; (2) whether requiring animals to collect earned sucrose promoted the organization of responses into bouts; and (3) whether only reinforcing bouts where interresponse time (IRT) variances were below a target promoted reproducible patterns of operant behavior.
Results
(1) Signaling reinforcer delivery with a cue increased learning rates but resulted in mice pressing the lever in fast succession until the cue turned on, rather than executing discrete bouts. (2) Requiring mice to collect the reinforcer between bouts had little effect on behavior. (3) A training strategy that directly reinforced bouts with low variance IRTs was not more effective than a traditional fixed ratio schedule at promoting reproducible action execution.
Conclusions
Together, our findings provide insights into the parameters of behavioral training that promote reproducible actions and that should be carefully selected when designing operant conditioning experiments.