Presentation Details
| Olfactory bulb gamma oscillations may represent a valence scaffold for the next sniff Frans Nordén1, Anja L.Winter1, Mikael Lundqvist1, Artin Arshamian1, Johan N.Lundström1, 2, 3. 1Department of Clinical Neuroscience, Stockholm, Sweden.2Monell Chemical Senses Center, Philadelphia, PA, USA.3Department of Otorhinolaryngology, Stockholm, Sweden |
Abstract
Predictive coding frameworks propose that sensory systems continuously generate top-down predictions that are compared with incoming sensory input. For the visual and auditory domains, gamma-band activity is considered to mainly convey bottom-up sensory evidence, while beta-band activity is thought to reflect top-down predictive signals. Whether the human olfactory system operates under a similar regime remains largely unknown. Building on previous findings demonstrating bidirectional, valence-related communication between the olfactory bulb (OB) and piriform cortex (PC), we recorded activity from both regions simultaneously using the electrobulbogram (EBG) method in 32 healthy participants. Odors varying in valence were presented across two consecutive sniffs, with valence switched in 20% of trials to create a sniff-by-sniff oddball paradigm. When odor valence was repeated, OB gamma activity increased during the second sniff, consistent with a refinement of the sensory representation. However, when odor valence changed between sniffs, this gamma enhancement disappeared, and OB gamma resetted to first-sniff levels. This pattern indicates that OB gamma activity reflects a refinement process that depends on the stability of sensory input across sniffs. These findings suggest that the human olfactory system engages gamma-mediated updating mechanisms and may participate in a broader predictive-coding architecture, although its implementation may differ from what is commonly demonstrated in vision and audition.
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