Metabolic state modulates neural processing of odors in the human olfactory bulb

• Published in: Biological psychology Vol. 187; p. 108770
• Main Authors: Iravani, Behzad, Frasnelli, Johannes, Arshamian, Artin, Lundström, Johan N.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-03-2024
• Subjects: Endocrinology; Medicin och hälsovetenskap; Metabolic state; Olfactory bulb; Olfactory system; Olfactory bulb; Olfactory system; Metabolic state; Endocrinology
• ISSN: 0301-0511; 1873-6246; 1873-6246
• DOI: 10.1016/j.biopsycho.2024.108770

The olfactory and endocrine systems have recently been shown to reciprocally shape the homeostatic processes of energy intake. As demonstrated in animal models, the individual’s metabolic state dynamically modulates how the olfactory bulb process odor stimuli using a range of endocrine signals. Here we aimed to determine whether the neural processing of odors in human olfactory bulb is modulated by metabolic state. Participants were exposed to food-associated odors, in separate sessions being hungry and sated, while neural responses from the olfactory bulb was obtained using electrobulbogram. We found significantly higher gamma power activity (51–100 Hz) in the OB’s response to odors during the Hunger compared to Sated condition. Specifically, EBG gamma power were elevated while hungry already at 100 ms after odor onset, thereby suggesting intra-bulbar modulation according to metabolic state. These results demonstrate that, akin to other animal models, hunger state affects OB activity in humans. Moreover, we show that the EBG method has the potential to measure internal metabolic states and, as such, could be used to study specificities in olfactory processing of individuals suffering from pathologies such as obesity or anorexia.
•In animals, the full olfactory system is affected by the individual’s feeding state.•In humans, feeding state has been shown to influence behavior and central responses.•We demonstrate here that hunger increase neural responses already in olfactory bulb.•The method can be used to assess feeding related problems in anorexia and obesity.