Harvard Scientists Reveal Secret Structure Behind How You Smell
Harvard scientists led by Sandeep (Robert) Datta mapped over a thousand smell receptors in mice, revealing they form organized horizontal stripes in the nose aligned with brain structures, challenging prior assumptions of random distribution. Their study, published in *Cell*, identified retinoic acid as a key factor in shaping this precise arrangement, offering new insights into how scent signals are processed.
Researchers at Harvard Medical School have uncovered a previously unknown structure in the biological basis of smell. Using mice, a team led by neurobiology professor Sandeep (Robert) Datta created the first detailed map of how more than a thousand smell receptors are organized inside the nose. Contrary to long-held beliefs, the neurons carrying these receptors form horizontal stripes extending from the top to the bottom of the nose, grouped by receptor type. This arrangement mirrors corresponding maps in the olfactory bulb of the brain, suggesting a direct alignment in how scent signals travel from the nose to the brain. The findings, published April 28 in *Cell*, challenge decades of scientific assumptions. While sensory receptors in the eyes, ears, and skin have long been mapped, smell remained the exception due to its complexity. Mice possess around 20 million olfactory neurons, each expressing one of over a thousand receptor types, making the system far more intricate than vision, which relies on just three receptor types. Early studies suggested receptors were randomly distributed, but Datta’s team used advanced genetic tools to revisit the question. By analyzing 5.5 million neurons from over 300 mice, the researchers combined single-cell sequencing with spatial transcriptomics. This revealed a clear pattern: neurons are organized into tightly packed, overlapping horizontal stripes based on receptor type. The consistency of this pattern across animals indicates a highly regulated system, similar to those governing vision, hearing, and touch. The study also identified retinoic acid, a molecule regulating gene activity, as crucial in shaping this arrangement. A gradient of retinoic acid within the nose appears to guide neuron positioning, determining receptor expression based on location. When researchers altered retinoic acid levels, the entire receptor map shifted, demonstrating its role in creating a precise and consistent olfactory system. Datta described the discovery as a conceptual shift, bringing order to a previously chaotic understanding of smell.
This content was automatically generated and/or translated by AI. It may contain inaccuracies. Please refer to the original sources for verification.