Featured Post from University of Florida

Study: What makes a smell bad?

Jan 29, 2026

3 min

Daniel Wesson
CaptionResizeWrap TextRemove


You wouldn’t microwave fish around your worst enemy — the smell lingers both in kitchen and memory. It is one few of us like, let alone have positive associations with.


But what makes our brains decide a smell is stinky?


A new study from UF Health researchers reveals the mechanisms behind how your brain decides you dislike — even loathe — a smell.


Or as first author and graduate research fellow Sarah Sniffen puts it: How do odors come to acquire some sort of emotional charge?


In many ways, our world capitalizes upon the importance of smells to influence emotions, running the gamut from perfumes to cooking and even grocery store design.


“Odors are powerful at driving emotions, and it’s long been thought that the sense of smell is just as powerful, if not more powerful, at driving an emotional response as a picture, a song or any other sensory stimulus,” said senior author Dan Wesson, Ph.D., a professor of pharmacology and therapeutics in the UF College of Medicine and interim director of the Florida Chemical Senses Institute.


But until now, researchers have puzzled over what circuitry connects the parts of the brain vital to generating an emotional response with those responsible for smell perception.


The team started off with the amygdala, a brain region that curates your emotional responses to sensory stimuli. Although all our senses (sound, sight, taste, touch and smell) interact with this small part of your brain, the olfactory system takes a more direct route to it.


“This is, in part, what we mean when we say your sense of smell is your most emotional sense,” Sniffen said. “Yes, smells evoke strong, emotional memories, but the brain’s smell centers are more closely connected with emotional centers like the amygdala.”


In the study, researchers looked at mice, who share neurochemical similarities with people. They can learn about odors and categorize them as good or bad.


After observing their behavior and analyzing brain activity, the team found two genetically unique brain cell types that allow odors to be assigned into a bucket of good feelings or bad feelings.


Initially, the team expected that one cell type would generate a positive emotion to an odor, and another would generate a negative emotion. Instead, the brain’s cellular organization gives the cells the capability of doing either.


“It can make an odor positive or negative to you,” Wesson said. “And it all depends upon where that cell type projects in your brain and how it engages with structures in your brain.”


But why is knowing more about how we categorize smells important? Well, for starters, smells — and our reactions to them — are a part of life. Sometimes, however, our reactions to them can be outsized, or take on a negative association so strong it disrupts how we live.


“We’re constantly breathing in and out and that means that we’re constantly receiving olfactory input,” Sniffen said. “For some people that’s fine, and it doesn’t impact their day-to-day life. They might even think, ‘Oh, odors don’t matter that much.’ But for people who have a heightened response to sensory stimuli, like those with PTSD or anxiety or autism, it’s a really important factor for their day-to-day life.”



In the future, the research could help clinicians adjust for heightened sensory response that some people struggle with in their everyday lives, Wesson added. One example? A patient associating a clinic’s smell with transfusions that made them queasy.


Based upon the receptor systems in these specific brain pathways, the team members believe they might be able to change those associations.


Potentially, medications could suppress some of these pathways’ activity to allow you to overcome stressful and aversive emotional responses.


Conversely, these pathways could be activated to restore enjoyment to things that people might have grown indifferent to — like those who lose their appetite from illness.


“Emotions in part dictate our quality of life, and we’re learning more about how they arise in our brain,” Wesson said. “Understanding more about how our surroundings can impact our feelings can help us become happier, healthier humans.”


This research was supported by funding from the National Institute on Deafness and Other Communication Disorders and the National Institute on Drug Abuse. Sarah Sniffen was supported by a fellowship from the National Institute on Deafness and Other Communication Disorders.

Connect with:
Daniel Wesson

Daniel Wesson

Associate Professor | Chair

Daniel Wesson is an expert in the sense of smell and how the brain processes sensory information.

AddictionBrain FunctionElectronic CigarettesSensory ProcessingSmell, Learning & Memory
Powered by

You might also like...

Check out some other posts from University of Florida

2 min

Machiavellianism boosts CEO pay, study finds

In an extensive study examining the relationship between personality traits and executive pay, CEOs who exhibit more Machiavellianism, characterized by motivation to achieve personal goals and 'win' social interactions, are more likely to have higher total pay and severance pay and to secure higher pay for those on their top management team. Aaron Hill, Ph.D., an associate professor at the University of Florida Warrington College of Business, and his co-authors determined that CEO's who scored higher on Machiavellianism were more motivated and successful in their negotiations. The team used a longitudinal sample of S&P 500 firms to compare compensation data with the executives' personality traits collected by expert clinical psychologists’ analyses of public video recordings. “Broadly, we find that CEO Machiavellianism positively relates to their own pay, their severance pay and the pay of their C-Suite or top management team,” Hill said. “The latter effect – on top management team pay – we find then predicts CEO pay raises. Our findings suggest that in this way, CEOs higher in Machiavellianism may pay their top management team members more to set up their own pay raises.” The team’s research highlights an underlying bias in how this trait can affect pay decisions. In response, those who set pay, such as boards of directors, should work on policies that reinforce the behaviors they want in their executives. They should also place leaders in a position to succeed and accentuate the positive aspects of their innate tendencies. “We all have tendencies that present tradeoffs in terms of having some positive aspects and some negative aspects,” Hill said. “Hopefully, as managers, we can acknowledge those and work to accentuate the positives and limit the potential downsides – in effect, take advantage of the positives and work to mitigate the negatives.” This research is published in the Journal of Applied Psychology.

4 min

Natural defenses: UF researchers use living infrastructure to protect Florida’s shores

Armed with a $7 million grant from the Army Corp of Engineers, University of Florida researchers are working to bolster shoreline resilience and restore troubled wetlands in St. Augustine through nature-based solutions. “The idea of nature-based solutions is to build what we sometimes refer to as green infrastructure, to use living, natural components as the building blocks,” said Andrew Altieri, Ph.D., an assistant professor with the Engineering School of Sustainable Infrastructure & Environment and interim director of the Center for Coastal Solutions, also known as CCS. Instead of building man-made structures to protect wetlands, for example, restoration crews can move dredged natural sediment otherwise destined for costly disposal to increase wetlands’ size and elevation, restoring their ability to protect shorelines from storm surge, keep pace with sea-level change, filter toxins, store carbon and provide habitats for wildlife.  The project is in concert with the Army Corps of Engineers’ goal to naturally reuse and repurpose at least 70% of dredged sediment into other natural areas to benefit habitats and restoration by 2030. “It is critical to understand, test and model how natural processes can be harnessed and strategically implemented to sustainably meet the challenge of rapidly intensifying coastal hazards while also providing environmental, economic and social benefits,” Altieri wrote in the project’s technical summary. Overall, the multi-disciplinary project closely examines patterns and processes of change in coastal landscapes. That includes wetlands — marshes and mangroves — and beach/dune systems. The project comes as these coastal areas are facing threats both natural and human. These areas are essential to wildlife, air quality, native vegetation, storm protection and the overall health of the ecosystem. A 2008 study by the U.S. Fish and Wildlife Service reported a net loss of about 361,000 acres of wetlands in the coastal watersheds of the eastern United States between 1998 and 2004 — an average net decrease of 59,000 acres each year, with experts citing sea-level rise as one of the primary factors. “We're trying to understand the patterns of that loss and what's leading to it,” Altieri said. “These systems are essentially the first and sometimes last line of defense against coastal hazards, risks that include storm surges and coastal flooding. They are forming a buffer, this kind of protective layer on our coast. But they're changing, generally for the worse and are in danger of being lost.” With this project, the CCS-led research team plans to advance the science, technology and engineering principles of nature-based solutions. With marshes, the primary concern is elevation loss, which can drown the vegetation critical to the ecosystem. They are sinking, eroding and succumbing to sea-level changes, Altieri said. “The plants are really important for trapping sediment and holding sediment,” he said. “You lose some of the plants, then you get more erosional loss and a lack of the accumulation of sediment.” Sediment is natural muck on the bottom of water bodies. “If we can add sufficient sediment to increase the elevation to a level where the plants thrive, then they will retain that sediment that's been added to hopefully trap more sediment and accumulate more biomass through their growth,” Altieri said. “It’s something that may need to be done periodically. You may stop that decline, but you may even reverse the process of loss and change the trajectory.” As a bonus, this process saves the cost of disposing of dredged sediment, which is usually piped offshore or to a materials-management area. This project is the next step for CCS-led coastal resilience efforts in St. Augustine. In 2024, CCS and WSP Environment & Infrastructure Inc. launched a coastal wetlands-restoration project to keep pace with sea level change and erosion. The 2025 work is a standalone project with separate funding, Altieri said. The current project also has more research disciplines and project partners, including UF researchers from Landscape Architecture, Geological Sciences and the School of Forest, Fisheries and Geomatic Sciences. “Storm surges, wave energy, coastal flooding – all of that can be slowed or reduced because of wetlands,” Altieri said. “They are basically like shock absorbers. These wetlands, beaches and dunes can be lost or eroded to some degree, but the upland area behind them is essentially protected.” Researching the resilience of dunes comes with a different set of dynamics. Here, they are looking at the plants that support the dunes – sea oats and panic grass, for example. That vegetation also provides a habitat for animals such as beach mice, turtles and birds. On the beach, the team also is looking at water energy and how grain size affects the stability of dunes. “It’s understanding water movement, water energy. How is that interacting with depositing sediment, moving sediment around, sorting sediment? With water, you tend to carry finer particles further than coarser materials,” he said. What does success look like after the award’s five years end? “We'll have an understanding of what's changing on our coasts and why,” Altieri said. “We'll have an understanding of how we can work within this system to modify the natural components and utilize the natural processes. And we will hopefully be working with partners through additional funding mechanisms to actually apply that towards implementation of solutions to increase coastal resilience.” The team also includes Peter Adams, Department of Geological Sciences; Julie Bruck, Department of Landscape Architecture, School of Landscape Architecture and Planning; Maitane Olabarrieta, ESSIE; Alex Sheremet, ESSIE; Nina Stark, ESSIE; Ben Wilkinson, Geomatics Program, School of Forest, Fisheries, and Geomatics Sciences; and Xiao Yu, ESSIE.

3 min

Florida scientists champion ‘Food Is Medicine’ movement to tackle national health crisis​

University of Florida researchers are calling for a national transformation in how we address the ongoing epidemic of obesity and Type 2 diabetes, starting with a fundamental shift in how we approach health, agriculture and food. Published recently in the Proceedings of the National Academy of Sciences, the article argues that fruits and vegetables must be treated not just as food — but as medicine.  With 73% of U.S. adults and 35% of children classified as overweight or obese, the authors warn that the crisis is not only an individual health issue but a national economic and security threat.  Andrew Hanson, Ph.D., a co-author and professor of horticultural sciences at UF/IFAS, emphasized a sense of urgency and collective responsibility toward solving this health crisis.  “This isn’t business as usual. We’re taking a public-interest view. This is the kind of thing we all need to be talking about. It’s too important not to,” he said.  The article proposes a roadmap for change, including creating five National Institutes of Health-supported “Food Is Medicine” centers across the U.S., with Florida as a leading candidate; scaling up domestic fruit and vegetable production to meet national dietary needs; partnering with food producer and processors to make healthy foods more accessible, affordable and appealing; and reforming medical and nutrition education to include horticultural sciences and vice versa. The article highlights that only 1 in 10 adults meets the recommended daily intake of fruits and vegetables, and that U.S. production falls far short of what’s needed to support a healthy population. The authors call for a dramatic expansion of fruit and vegetable production, especially high-impact crops like berries, leafy greens and carrots.  Christopher Gunter, Ph.D., professor and chair of the UF/IFAS Department of Horticultural Sciences, said the team’s goal is to push the role fruit and vegetables crops can play in improving human health into the national consciousness. “As a discipline, horticulture and the science of fruit and vegetables have been largely ignored in this conversation,” Gunter said. “Our goal is to move the needle on health with fruit and vegetables.”   Hanson said about 80% of the nation’s cropland is used to grow soybeans, corn and wheat — most of which are processed into products with low nutritional value that contribute to the obesity and Type 2 diabetes epidemic.  Mike Jaffee, M.D., a co-author and professor of neurology in the UF College of Medicine, stressed the broader implications of a high-vegetable diet on brain health.  “Obesity and insulin resistance are linked to inflammation and neurodegeneration. We’re living longer, but our brains aren’t keeping up. That’s where the real cost to individuals and the health care system comes in,” he said.  Gunter agreed, adding, “This epidemic reduces the longevity and productivity of our citizens. It limits the momentum communities need to grow healthy and resilient families.”  Hanson pointed out that higher socioeconomic groups are better positioned to meet dietary recommendations, making this not just a health issue, but a deeply embedded social and economic one.  “This crisis takes an unduly large toll on people with lower incomes and less time. To eat enough fruits and vegetables in the current system, you need substantial income and time to prepare food. That’s a luxury many don’t have,” he said.  The authors argue that farmers bring essential knowledge to the table.   “They understand how environmental factors impact nutritional quality,” Gunter said.

View all posts
Powered by