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All forms of life — even the smallest single cell microbes — have evolved mechanisms to detect sensory cues in the environment. These sensory machines do not capture even a fraction of the information in the outside world. Instead evolution tailors sensory systems to suit each animal’s specific ecological niche, enabling detection of that which is crucial for survival and ignoring the rest. This principle — that we use perception to solve our unique problems of existence — has driven the development of senses ranging from the familiar (our five senses of smell, touch, taste, hearing and vision) to the exceptional (e.g. the multi-foveal visual system of raptors that enable prey tracking from the air, the ultrasonic echolocation system in bats, and the “third eye” in pit vipers that enables them to catch food by detecting heat). Sensory modalities can also vanish as their utility is diminished — cavefish whose entire existence is spent in the dark, for example, have no need for the functioning eyes of their ancestors. 

As higher primates our sensory world is dominated by visual stimuli, and our brains have evolved astonishingly sophisticated mechanisms to enable sight. Indeed, depending upon how one does the math, more than a third of the human brain may be devoted to visual processing. But for nearly all animals who are not primates, the most important information in the outside world comes not from sights or sounds but smells — volatile chemical cues that tell animals about the proximity of food, the availability of appropriate mates, the lurking danger of a nearby predator. As one might predict, the importance of olfaction in non-primates is reflected by a relatively large apportionment of neural real estate; one third of the brain of a mouse is devoted to processing smells. 

A central idea within the lab is that we can learn general principles about how the brain usefully organizes sensory information and converts that information into action by specifically exploring the neural mechanisms that underlie olfaction. But despite the fact that smell was the first sense to evolve, the sense that enables most animals to interact with their environment, we understand little about how the brain “sees” the outside olfactory world. How does the brain identify, distinguish and remember odors? And how is that information coupled to motor systems that enable appropriate and meaningful behavioral responses to signals from the outside world?

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