— — Zachary MainenFor years, mouse facial movements have mostly served as a way for researchers to gauge an animal’s pain levels. These decision variables underlie the three strategies mice use to choose between two foraging sites. Even when mice employ one strategy, they still monitor other decision variables and can switch tactics, Cazettes reported in a 2023 paper. A model based on electrophysiological readouts was able to decode decision variables earlier than a model based on facial movement. Optogenetic inactivation of M2 produced immediate motor changes that hampered the facial movement model’s ability to predict decision variables.