Mouse navigation strategies for odor source localization

Navigating an odor landscape is a critical behavior for the survival of many species, including mice. One ethologically relevant mouse behavior is locating food using odor concentration gradients. To model this behavior, we use a naturalistic open field odor-based spot-finding task, examining navigation strategies as mice search for and approach an odor source. Mice were trained to navigate to odor sources paired with food reward. We detected behavioral changes consistent with localization of the odor source when mice were 10cm away from the source. These behaviors included both orientation towards the source and increased exploration time. We found that the amplitude of "casting," lateral back and forth head movement, increased exponentially with proximity to the source. We then created concentration-dependent models to simulate mouse behavior, which provided evidence for a serial-sniffing strategy (sampling concentration, moving in space, then sampling again) and a stereo-sniffing strategy (inter-nostril comparison of concentration in a single sniff). Together, these results elucidate key components of behavioral strategies for odor-based navigation.