This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: When you walk into a bakery and smell fresh cookies, the enticing smell draws you in. After you eat a handful of cookies, though, the same smell likely doesn't send you back for more.
Researchers in the McKelvey School of Engineering at Washington University in St. Louis sought to determine the biological mechanisms in the brain that controllably alters odor-evoked behavior by using an unlikely model—a locust. Barani Raman, the Dennis & Barbara Kessler Professor in the Department of Biomedical Engineering, along with students in his lab, studied how two neuromodulators with opposite effects, dopamine and octopamine, changed how locusts smelled and reacted to odors.
Results of their research were published in the Journal of Neuroscience Sept. 14, 2026. Dopamine is involved in the brain's reward system, or a rush after doing things well. When the locusts' brains were exposed to dopamine, the olfactory neural networks became highly sensitive to the odors presented, which included what to humans smell like grass, lemon or citrus, rose, almond and a spicy floral scent.
The locusts increased the neural responses to all odorants, and an appetitive behavior response, which involved opening their sensory appendages close to mouth parts called palps that grab or touch the food. The team also exposed the locusts to octopamine, an organic chemical behind the "fight-or-flight" neuromodulator in insects and positive learning, then presented the same odors. They found that the locusts' odor-related brain activity and their behavioral response were reduced.
Raman said the behavior differences were not random. "This was a patterned increase and decrease in neural responses evoked by odorants presented that still maintained the identity of the stimulus," Raman said. "The cookie still smells like a cookie, but maybe the response is stronger or lesser, depending on which neuromodulator is released." It is normal for an organism to change its behavior based on its environment: if there is a food scarcity, it will look for food more than when food is plentiful.
But in this case, nothing in its environment changed—only the way the brain processed the odors changed, Raman said. The team went in search of the mechanism behind the behavior responses. They looked at a subset of neurons called local neurons that are GABAergic, or neurons that produce their effects through the GABA neurotransmitter, an inhibitory chemical messenger in the central nervous system.
Extract — continue reading at the source.
