News brief
Scientists have long puzzled over the organisation of the sense of smell, but a recent study using mice has revealed a hidden map of smell receptors in the nose. These receptors are not randomly distributed as previously thought; instead, they are arranged in orderly, overlapping stripes. This discovery not only challenges existing beliefs but also mirrors the way smell information is processed in the brain, suggesting a coordinated system from the nose to neural circuits.
Key points
- Smell receptors are organised in neat stripes.
- The nasal map aligns with brain structures.
- Retinoic acid guides receptor organisation.
Mapping Smell Receptors
In a groundbreaking study, researchers mapped over a thousand types of smell receptors in mice, revealing a structured arrangement within the nose. These receptors, carried by neurons, form horizontal bands grouped by type, challenging the long-held belief that their distribution was random. This discovery provides a new perspective on how olfactory information is organised.
The research team, led by Professor Sandeep (Robert) Datta, utilised advanced genetic tools to analyse approximately 5.5 million neurons across more than 300 mice. This comprehensive approach allowed them to identify the specific receptors each neuron expressed and their precise locations.
Connection to the Brain
The newly discovered map in the nose aligns with corresponding maps in the brain's olfactory bulb, offering insights into how scent information travels from the nose to neural circuits. This alignment suggests a coordinated system that mirrors the organisation seen in other senses like vision and hearing.
This finding is significant because it addresses a long-standing gap in our understanding of olfactory processing. While the arrangement of sensory receptors in the eyes, ears, and skin has been well-documented, the sense of smell had remained elusive until now.
Role of Retinoic Acid
The study also explored how this precise receptor structure develops, identifying retinoic acid as a crucial factor. This molecule, known for regulating gene activity, appears to guide the positioning of neurons and the activation of specific smell receptors.
When researchers manipulated retinoic acid levels, the entire receptor map shifted, demonstrating its role in maintaining the precise organisation of smell receptors. This discovery highlights the intricate mechanisms behind the development of olfactory systems.
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