Similar perceived odors may induce similar systemic brain activity

Abstract

How we discriminate odors is an important question. According to previous studies, perceiving distinct odors begins with activating distinct combination of olfactory receptor (OR) repertoire in olfactory receptor neurons (ORN). This effect consecutively activates distinct ORN and these distinct ORN activities encode in olfactory bulb. Encoded odor information finally is processed in the brain so we can perceive and discriminate odors. However, the questions are still unsolved why different OR repertoires induce different brain activities, and similar neural encoding of the olfactory bulb induces distinct odor responses. To solve these questions, it is necessary to study the odor responses in the brain in which the odor information is lastly processed. Thus, this study focused on how similar perceiving odors process in the brain. We used two odors, 2-acetylpyrazine (AP) and 2, 3, 5-trimethly pyrazine (TP) that describe as similar perceptual descriptor but activating different OR repertoire. To measure the direct brain signal, EEG was used to understand how participants process odor in their brain. Power spectrum and event related spectral perturbation (ERSP) of EEG frequency bands are used to verify similarity between responses upon AP and TP treatment. Interestingly, AP and TP induce similar patterns of power spectrum in total electrodes. These results suggest that these odors activated similar regions in the brain. Also ERSP results of AP and TP suggest that AP and TP induce similar pattern of brain activity in the time-scale. These two results emphasize that AP and TP may activate similar olfactory pathway in the brain. However, total intensities of power spectrum are different between AP and TP. These differences may imply how people are able to distinguish these two odors. Based on these results, similar perceiving odors may induce similar systemic brain activity. and odors may be distinguished by different intensity of the brain activities.