Fast changing smells can teach mice about space

Mice can sense extremely fast and subtle changes in the structure of odours and use this to guide their behaviour, according to a new study by UCL and Francis Crick Institute researchers. Odour plumes, like the steam off a hot cup of coffee, are complex and often turbulent structures, and can convey meaningful information about an animal's surroundings, like the movements of a predator or the location of food sources. But it has previously been assumed that mammalian brains can't fully process these temporal changes in smell because they happen so rapidly, much faster than an animal can sniff. Using behavioural experiments where mice were exposed to incredibly short bursts of odour, neural imaging, electrophysiology and computer models, the scientists found that mice can, in fact, detect very rapid fluctuations within odour plumes, at rates previously not thought possible. They also showed that mice can use this information to distinguish whether odours are coming from the same or different sources, even if they are very close to each other. This suggests that the mammalian olfactory system, responsible for the sense of smell, is also key in processing the awareness of physical space and surroundings, guiding decisions important to survival. Senior author Professor Andreas Schaefer (UCL Neuroscience, Physiology & Pharmacology and Francis Crick Institute) said: "From an evolutionary point of view our findings make sense as they help to explain why there is a lot of computational power within the olfactory bulb, the part of the brain where the nose sends signals to.