First-Ever Smell Map Is a Breakthrough in Sensory Research, a Step to Help Us Tackle Loss of Smell

Many people view smell as less important than their other senses, despite its role in interpreting our environment, experiencing taste, and detecting danger. For scientists, olfaction (the perception of molecules suspended in the air) still remains full of unanswered questions, particularly regarding the organization of olfactory receptors in the nose.

To help shed light on this mysterious sense, researchers at Harvard Medical School have created the first detailed map of how more than a thousand olfactory receptors are arranged in the nose. This work marks a major advance in olfactory research and fills a long-standing gap in our understanding of the senses.

“Our results bring order to a system previously thought to lack order, which conceptually changes how we think it works,” said the study’s lead author, Sandeep Datta, a professor of neurobiology at Harvard’s Blavatnik Institute, in a press release.

The results, published in Cellcould one day support the development of new and improved therapies for patients who have lost their sense of smell.

Olfaction is always mysterious

Compared to other senses such as vision, hearing and touch, olfaction remains poorly understood at the biological level. Scientists already have detailed maps showing how receptors in the eyes, ears and skin, as well as the corresponding brain areas, are organized.

“Olfaction is the only exception; it’s the sense that has been missing the map for a very long time,” Datta said.

One of the reasons for the delay is complexity. While vision relies on only three main types of receptors, olfaction relies on thousands.

Over the past 35 years, researchers have identified many of these receptors and attempted to map them, but they have largely assumed that the receptors, although confined to certain areas, are arranged randomly, without a coherent pattern. Interest in this question has grown in recent years, in part due to the sharp increase in smell loss following the COVID-19 pandemic, as well as advances in genetic techniques that allow scientists to study the system in much more detail.

Learn more: How to improve your sense of smell and taste

Olfactory receptors are surprisingly highly organized

In the new study, the research team used two genetic techniques, called single-cell sequencing and spatial transcriptomics, to analyze approximately 5.5 million neurons from more than 300 mice. This allowed them to pinpoint the exact location and connections of receptors and neurons.

“This is arguably the most sequenced neuronal tissue ever made, but we needed this scale of data to understand the system,” Datta said in the release.

The resulting map showed that olfactory receptors are arranged in tight horizontal bands in the mice’s noses, grouped by type. Rather than being random, the system is very structured.

“We show that development can achieve this feat of organizing a thousand different olfactory receptors into an incredibly precise and consistent map across all animals,” Datta said.

The team also demonstrated that this map of receptors aligns with existing maps of the brain’s odor processing centers, providing new insight into how information flows from the nose to the brain.

Improving Therapies for Loss of Smell

The researchers next aim to determine the exact order of these receptor bands. They are also extending their work to human tissue to see how well the mouse map translates across species.

A deeper understanding of how smell works could potentially support the development of targeted therapies, including stem cell treatments or even brain-computer interfaces. Losing the sense of smell can have surprisingly serious effects on mental health, leading to isolation, anxiety symptoms and depression.

“Smell has a very profound and pervasive effect on human health, so restoring it is not only for pleasure and safety, but also for psychological well-being,” Datta added. “Without understanding this map, we are doomed to failure in developing new treatments. »

This article does not offer medical advice and should be used for informational purposes only.

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