Presentation Details
| Exploring lateralized processing in the human olfactory system Clara U Raithel, Jaylen Worthy, Rhianna Sullivan, Thorsten Kahnt. National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA |
Abstract
The human olfactory system receives sensory information from two anatomically distinct nostrils. Existing evidence on how these separate streams of information are processed in the human brain and used for behavior is inconclusive. Furthermore, nasal cycling is often ignored in the existing literature or discussed purely as an afterthought. In this study, we ask how the olfactory system encodes sensory inputs from the left and right nostril, and how both behavior and neural representations are influenced by nasal cycle. For this purpose, we developed a novel olfactory perceptual decision-making task in which we deliver binary odor mixtures to the left or right nostril and ask participants to indicate the dominant component in the mixture. We simultaneously record brain activity using fMRI and measure nasal airflow in each nostril separately to account for differences in neural representations as a function of the nasal cycle. Our findings suggest that participants can successfully discriminate unilaterally delivered odor mixtures. Interestingly, although participants cannot reliably determine the site of odor stimulation (left vs. right nostril), brain responses in primary olfactory regions are highly lateralized, showing significantly stronger responses to ipsi- compared to contralateral odor delivery. This finding is broadly in line with the existing empirical evidence on primarily ipsilateral anatomical projections from the olfactory periphery to the primary olfactory cortex.
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No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author.