A whiff of microwaved fish may linger in your kitchen—and your memory—but what makes some smells universally unpleasant while others draw fond nostalgia? Recent research from the University of Florida uncovers how our brains assign emotional value to odors, offering insights that could reshape approaches to sensory health and even clinical treatment of scent-related distress (SciTechDaily).
For Thais who cherish the bustling aromas of street markets or the stinging tang of fermented fish (pla ra), the subjective nature of “good” and “bad” smells is more than a curiosity—it’s a matter woven into daily life, heritage, and even mental wellbeing. As major Thai cities grow ever more cosmopolitan, and with mental health awareness rising, understanding exactly how our brain selects which odors to embrace (or reject) could have widespread impacts.
The study, published this month in Molecular Psychiatry, zeroed in on the amygdala, the brain’s emotional center. Unlike other senses—sight, hearing, touch, and taste—smell travels directly to the amygdala via specialized neural pathways. “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,” explained the study’s senior author, a professor of pharmacology and therapeutics at the UF College of Medicine.
Researchers found that the brain contains two genetically unique types of cells that help sort olfactory information as positive or negative. Using mice, which share important neurochemical similarities with humans, they measured behavioral responses and tracked brain activity. Surprisingly, these cell types are flexible: their role—whether to generate a positive or negative reaction—depends on their connections and how they interact with other brain structures. As the study’s lead author, a graduate research fellow, stated, “It can make an odor positive or negative to you. And it all depends upon where that cell type projects in your brain and how it engages with structures in your brain.”
This discovery stands to benefit people who experience outsized responses to specific smells. Some Thais living with anxiety disorders, post-traumatic stress disorder (PTSD), autism, or heightened sensory sensitivities report that even mild odors can provoke debilitating distress. For example, certain clinic or hospital smells are often linked to past medical experiences, affecting willingness to seek healthcare. “We’re constantly breathing in and out and that means that we’re constantly receiving olfactory input,” noted the lead author. “For some people, that 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… it’s a really important factor for their day-to-day life.”
Clinical applications for this discovery are promising. Thai occupational therapists, educators, and mental health professionals might eventually help clients “re-wire” adverse scent associations by targeting these neural pathways. This could help, for instance, a young student who can’t concentrate in class due to the cleaning agents used in school, or a patient deterred from seeking treatment because hospital odors revive distressing memories.
Moreover, the findings may lead to new medications that suppress or activate certain brain pathways, either muting distressing emotions tied to smells or restoring lost sensations of pleasure—such as reviving appetite in those undergoing medical treatments. As the senior author emphasized, “Emotions in part dictate our quality of life, and we’re learning more about how they arise in our brain. Understanding more about how our surroundings can impact our feelings can help us become happier, healthier humans.”
Thailand’s relationship with odor is deeply cultural. Some local dishes are prized for their pungency, such as durian and nam pla (fish sauce), while foreigners often cite them as “bad.” The research underscores how cultural learning and personal experience mesh with biological wiring in forming scent judgments—supporting the long-held Thai proverb, “One man’s meat is another man’s poison,” but here, applied through the nose.
Looking ahead, this research may catalyze more studies in Southeast Asia, where climate, cuisine, and lifestyle are rich in sensory diversity. It could also prompt broader conversations about inclusive design, from hospital waiting rooms to public transit—to ensure people aren’t inadvertently overwhelmed by the scents of public spaces.
For Thai readers, practical steps include being mindful of scent sensitivities at home, work, and in community spaces. For teachers and business owners, offering fragrance-free environments or warning of strong odors can help build inclusivity. Those affected by aversive odor reactions may soon have new hope through tailored therapy or medical support, rooted in these pioneering brain insights.
For more information on the original research, see the publication in Molecular Psychiatry (DOI: 10.1038/s41380-025-03075-0) and the SciTechDaily article.