Evaluation of study design variables and their impact on food-maintained operant responding in mice

Desirae M. Haluk, Kevin Wickman

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Operant conditioning paradigms are useful for studying factors involved in reward, particularly when combined with the tools of genetic manipulation in mice. Published operant studies involving mice vary widely with respect to design, and insight into the consequences of design choices on performance in mice is limited. Here, we evaluated the impact of five design variables on the performance of inbred male mice in operant tasks involving solid food pellets as reinforcing agents. We found that the use of lever-press or nose-poke during FR1 sessions did not impact the performance of C57BL/6 mice, but that the lever-press approach correlated with enhanced performance during PR testing. While FR1 session duration had a notable impact on the rate of acquisition of food-maintained responding, performance during FR1 and PR sessions was largely unaffected. Higher order schedules of reinforcement (FR3 and FR5) led to elevated responding during both FR and PR sessions, and improved the correspondence between rewards earned and consumed. Single and group-housed mice performed indistinguishably during FR1 and PR sessions, while environmental enrichment combined with group housing accelerated the rate of acquisition of food-maintained responding while decreasing responding during PR testing. Finally, while C57BL/6 and 129/Sv mice exhibited comparable behavior during FR1 sessions, C57BL/6 mice tended to acquire food-maintained responding faster than 129/Sv counterparts, and exhibited elevated responding during PR testing. Altogether, our findings indicate that while operant performance for food in mice is relatively insensitive to many study parameters, experimental outcomes can be shaped predictably with proper design decisions.

Original languageEnglish (US)
Pages (from-to)394-401
Number of pages8
JournalBehavioural Brain Research
Volume207
Issue number2
DOIs
StatePublished - Mar 5 2010

Bibliographical note

Funding Information:
The authors would like to thank Dr. Stan Floresco for his assistance with Med-PC programming and for his helpful suggestions throughout the course of the study. We would also like to thank members of the Wickman laboratory for providing helpful input on the manuscript, and Tristan Driscoll for his assistance with the mouse colony. This project was funded by NIH grants MH061933 and DA011806 (KW).

Keywords

  • Enrichment
  • Instrumental learning
  • Reinforcement
  • Reward
  • Strain

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