How do mice smell? - briefly
Mice detect odors through an extensive olfactory epithelium containing millions of odor‑receptor neurons and a vomeronasal organ specialized for pheromonal cues. Their system can discriminate volatile chemicals at concentrations as low as parts per billion.
How do mice smell? - in detail
Mice rely on a highly developed olfactory system to detect chemical cues essential for foraging, predator avoidance, and social communication. The nasal cavity contains an extensive olfactory epithelium lined with millions of sensory neurons, each expressing a single type of odorant receptor (OR). Approximately 1,100 functional OR genes are present in the mouse genome, providing a repertoire far larger than that of humans.
Odorant molecules dissolve in the mucus covering the epithelium and bind to receptors, triggering a cascade that generates electrical signals. These signals travel via the olfactory nerve to the olfactory bulb, where glomeruli sort inputs by receptor type. From the bulb, information proceeds to the piriform cortex, amygdala, and hypothalamus, integrating odor perception with memory, emotion, and hormonal responses.
In addition to the main olfactory system, mice possess a vomeronasal organ (VNO) specialized for detecting pheromones and other non-volatile compounds. The VNO sends signals through the accessory olfactory bulb to limbic structures, influencing reproductive and territorial behaviors.
Key functional characteristics include:
- Detection thresholds in the low picomolar range for many volatile compounds.
- Ability to discriminate thousands of odorants within milliseconds.
- Rapid adaptation mechanisms that reset receptor sensitivity after prolonged exposure.
- Genetic plasticity allowing selective breeding for altered odor perception.
Experimental techniques such as electroolfactography, calcium imaging of olfactory neurons, and optogenetic manipulation provide quantitative data on receptor activation and neural circuit dynamics. Comparative studies show that mice can resolve odor mixtures more efficiently than humans, reflecting the greater density of OR-expressing neurons and larger olfactory bulb surface area.
Overall, the mouse olfactory apparatus combines a vast receptor repertoire, precise neuronal mapping, and integrated central processing to achieve exceptional chemical sensing capabilities.