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| Poster #250 Odor concentration and perceived odor intensity processing within and between the human olfactory bulb and piriform cortex |
| Irene Zanettin1, Frans Nordén1, Mikael Lundqvist1, Artin Arshamian1, Johan N. Lundström1,2,3 1Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, --, Sweden 2Monell Chemical Senses Center, Philadelphia, PA, United States 3Department of Otorhinolaryngology, Karolinska Institutet, Stockholm, --, Sweden |
Odor intensity plays a key role in how humans perceive and interpret their surroundings. In several species, neural oscillations have been linked to odor concentration processing with evidence suggesting that the oscillation amplitude is modulated by the strength of odor concentration. However, no studies have explored whether oscillatory activity in the human olfactory bulb (OB) and piriform cortex (PC) is related to odor concentration and how it differs from perceived odor intensity. To this end, we recorded odor-dependent neural activity using EEG in the OB and PC of human participants while collecting trial-by-trial intensity ratings. Our findings show that no information regarding odor concentration is transmitted between OB and PC through oscillatory activity. Instead, perceived intensity is processed in a bottom-up fashion in the OB gamma band 200 ms after odor delivery, then transmitted to the PC via gamma oscillations for further processing. To better understand the relationship between odor intensity processing, cognition, and neural oscillations, we then analyzed burst activity in the beta and gamma bands. We found that odor concentration predicted OB and PC beta burst behavior, but results did not survive cluster correction. In contrast, for perceived intensity, we found significant gamma burst activity in the OB around 800-1100 ms, coinciding with significant beta burst activity in the PC during the same period. This timing matched the one found in the coherence spectrum, during which top-down information from the PC conveys refined information back to the OB in the beta band. The late timing of activation, with converging evidence across analyses, suggests that perceived intensity is mainly regulated by top-down information. |