Scientists in the U.S. and Canada have discovered a new structure in the human olfactory senses, creating the world's first “smell map” of 5.5 million neurons in over 300 mice. This discovery indicates that the arrangement of scent receptors isn't as random as previously believed. The map was created using single-cell sequencing to identify which smell receptors were expressed in neurons and then used spatial transcriptomics to identify where these receptors were located. The researchers found that neurons were arranged in horizontal stripes from the top of the nose to the bottom, based on what receptor they expressed. This is a significant discovery and could help scientists treat conditions where a person's sense of smell is damaged or completely lost entirely.