Mammalian odour-guided navigation behaviour and neural processing in relation to the odour environment

Animal survival in the wild is largely dependent on their ability to locate food sources, find mates, and avoid predators - tasks which are all heavily reliant on their sense of smell. However, to be adept at these behaviours, animals must navigate a complex odour landscape where odour can be released in many forms, including odour trails and airborne odour plumes. Odour plumes result when an odour is carried by ambient wind, where its structure changes with distance from the odour source, providing potential navigational cues to searching animals. Odour plumes adopt a variety of structures depending on the odour landscape, such as pulled odour filaments that are interleaved with pockets of air in a turbulent environment. Due to advancements in fluid dynamics technology allowing for the detailed measurement of airborne odour plumes, recent studies have begun to explore how odour plume properties affect olfactory search behaviour in mammals. For example, our own studies have demonstrated that intermittency is an odour plume property that can inform olfactory search, is encoded in early stages of olfactory processing within the olfactory bulb, and is subject to changes in representation based on active sampling strategies. This review summarizes how mammalian odour-based navigation depends on and can be guided by odour plume properties.