How Smell Works: Scientists Discover Hidden Structure in the Nose & Brain

Scientists have discovered a previously unknown, highly organized structure within the mouse nose that dictates how the brain perceives smells. The finding, published April 30, 2026, challenges long-held assumptions about the sense of smell and could pave the way for restoring lost olfactory function.

Researchers at Harvard Medical School mapped over a thousand types of smell receptors in mice and found they aren’t randomly distributed. Instead, the receptors are arranged in neat, overlapping stripes based on receptor type, forming a “hidden map” within the nasal cavity. Remarkably, this organization mirrors the way smell information is mapped in the brain, suggesting a coordinated system from the nose to neural circuits.

Mapping the Sense of Smell

For decades, the biological basis of smell has remained less understood compared to other senses like vision, hearing, and touch. “Olfaction is super-mysterious,” said Sandeep (Robert) Datta, professor of neurobiology in the Blavatnik Institute at Harvard Medical School. The new study represents a significant step toward unraveling this mystery.

The research team utilized advanced techniques, including single-cell sequencing and spatial transcriptomics, to analyze approximately 5.5 million neurons across over 300 individual mice. Single-cell sequencing allowed them to identify which receptor each olfactory sensory neuron expresses, while spatial transcriptomics helped pinpoint the location of those receptors within the nose.

“We looked at each mature olfactory sensory neuron one at a time, to identify which receptor is being expressed,” explained Dr. Datta. This detailed analysis revealed the unexpected organization of the smell receptors into distinct bands.

How the System Works

Smells are detected by olfactory sensory neurons in the nasal cavity. In mice, each neuron expresses one of 1,172 different receptors, each designed to detect a specific type of odor. Previously, it was believed these receptors were scattered randomly throughout the nasal lining. The new research demonstrates that this is not the case.

The discovery of this organized mapping system is significant because other senses, such as hearing and touch, are known to utilize similar sensory maps. For example, different sound frequencies are processed at different locations within the cochlea of the inner ear. The finding suggests that smell may operate under similar principles of spatial organization.

Implications for Future Research

Understanding the organization of the olfactory system could have important implications for restoring the sense of smell in individuals who have lost it due to injury or disease. Damage to olfactory neurons can result from viral infections, head trauma, or neurodegenerative conditions.

By understanding how the receptors are arranged and how this arrangement relates to brain activity, researchers may be able to develop strategies to regenerate olfactory neurons or bypass damaged areas of the system. The precise mapping of the olfactory system could also lead to a better understanding of how smells evoke memories and emotions, given the strong connection between olfaction and brain regions involved in these processes.

The researchers emphasize that this study was conducted in mice, and further research is needed to determine whether the same organizational principles apply to the human olfactory system. However, the findings provide a crucial foundation for future investigations into the complexities of smell and its impact on our perception of the world.