Makine Sense of Scents in Mice

For many animals, making sense of the clutter of sensory stimuli is often a matter of literal life or death. Exactly how animals separate objects of interest, such as food sources or the scent of predators, from background information, however, remains largely unknown. Even the extent to which animals can make such distinctions, and how differences between scents might affect the process were largely a mystery – until now. In a new study, described in an August 3, 2014 online paper in Nature Neuroscience, a team of researchers led by Dr. Venkatesh Murthy, Professor of Molecular and Cellular Biology at Harvard University, showed that while mice can be trained to detect specific odorants embedded in random mixtures, their performance drops steadily with increasing background components. The team also included Drs. Dan Rokni, Vikrant Kapoor, and Vivian Hemmelder, all from Harvard University. "There is a continuous stream of information constantly arriving at our senses, coming from many different sources," Dr. Murthy said. "The classic example would be a cocktail party – though it may be noisy, and there may be many people talking, we are able to focus our attention on one person, while ignoring the background noise. "Is the same also true for smells?" he continued. "We are bombarded with many smells all jumbled up. Can we pick out one smell "object" – the smell of jasmine, for example, amidst a riot of other smells? Our experience tells us indeed we can, but how do we pick out the ones that we need to pay attention to, and what are the limitations?" To find answers to those, and other, questions, Dr. Murthy and colleagues turned to mice. After training mice to detect specific scents, researchers presented the animals with a combination of smells – sometimes including the "target" scent, sometimes not.