PT  - JOURNAL ARTICLE
AU  - Hongli Wang
AU  - Heather K. Ortega
AU  - Huriye Atilgan
AU  - Cayla E. Murphy
AU  - Alex C. Kwan
TI  - Pupil Correlates of Decision Variables in Mice Playing a Competitive Mixed-Strategy Game
AID  - 10.1523/ENEURO.0457-21.2022
DP  - 2022 Mar 01
TA  - eneuro
PG  - ENEURO.0457-21.2022
VI  - 9
IP  - 2
4099  - http://www.eneuro.org/content/9/2/ENEURO.0457-21.2022.short
4100  - http://www.eneuro.org/content/9/2/ENEURO.0457-21.2022.full
SO  - eNeuro2022 Mar 01; 9
AB  - In a competitive game involving an animal and an opponent, the outcome is contingent on the choices of both players. To succeed, the animal must continually adapt to competitive pressure, or else risk being exploited and lose out on rewards. In this study, we demonstrate that head-fixed male mice can be trained to play the iterative competitive game “matching pennies” against a virtual computer opponent. We find that the animals’ performance is well described by a hybrid computational model that includes Q-learning and choice kernels. Comparing between matching pennies and a non-competitive two-armed bandit task, we show that the tasks encourage animals to operate at different regimes of reinforcement learning. To understand the involvement of neuromodulatory mechanisms, we measure fluctuations in pupil size and use multiple linear regression to relate the trial-by-trial transient pupil responses to decision-related variables. The analysis reveals that pupil responses are modulated by observable variables, including choice and outcome, as well as latent variables for value updating, but not action selection. Collectively, these results establish a paradigm for studying competitive decision-making in head-fixed mice and provide insights into the role of arousal-linked neuromodulation in the decision process.