First Detailed Smell Map of Mouse Nose Reveals Highly Organized Olfactory System

Two studies published April 28 in the journal Cell overturn the long-held belief that the nose's odor detectors are randomly arranged. Researchers at Harvard Medical School and Harvard University mapped over 1,100 types of odor receptors in the mouse nose, revealing a highly organized stripe pattern. Sandeep Robert Datta and colleagues analyzed five million neurons from hundreds of mice using fine-scale genetic techniques, finding that neurons with similar receptor types form tight horizontal bands. A separate atlas study mapped how these receptors connect to the brain, producing maps consistent across individual mice. The molecule retinoic acid, present in a gradient across the nose, guides which neurons express which receptor. This work could lead to therapies for smell loss, which has been exacerbated by Covid-19. Humans have about 400 odor receptor types, and Datta suspects a similar organization exists. The research resolves a major question in olfaction and opens new avenues for understanding scent processing.