MalGa, Department of Civil, Chemical and Mechanical Engineering, University of Genova, Genova, Italy; Institut de Physique de Nice, Université Côte d’Azur, Centre National de la Recherche Scientifique, Nice, France; Department of Physics and INFN Genova, University of Genova, Genova, Italy
NSF-Simons Center for Mathematical and Statistical Analysis of Biology, Harvard University, Cambridge, United States; Physics & Informatics Laboratories, NTT Research, Inc, Sunnyvale, United States; Center for Brain Science, Harvard University, Cambridge, United States
MalGa, Department of Civil, Chemical and Mechanical Engineering, University of Genova, Genova, Italy; Institut de Physique de Nice, Université Côte d’Azur, Centre National de la Recherche Scientifique, Nice, France
Foraging mammals exhibit a familiar yet poorly characterized phenomenon, ‘alternation’, a pause to sniff in the air preceded by the animal rearing on its hind legs or raising its head. Rodents spontaneously alternate in the presence of airflow, suggesting that alternation serves an important role during plume-tracking. To test this hypothesis, we combine fully resolved simulations of turbulent odor transport and Bellman optimization methods for decision-making under partial observability. We show that an agent trained to minimize search time in a realistic odor plume exhibits extensive alternation together with the characteristic cast-and-surge behavior observed in insects. Alternation is linked with casting and occurs more frequently far downwind of the source, where the likelihood of detecting airborne cues is higher relative to ground cues. Casting and alternation emerge as complementary tools for effective exploration with sparse cues. A model based on marginal value theory captures the interplay between casting, surging, and alternation.
