Spatiotemporal Processing of Bimodal Odor Lateralization in the Brain Using Electroencephalography Microstates and Source Localization

Christine Ida Hucke; Rebekka Margret Heinen; Marlene Pacharra; Edmund Wascher; Christoph van Thriel

doi:10.3389/fnins.2020.620723

Spatiotemporal Processing of Bimodal Odor Lateralization in the Brain Using Electroencephalography Microstates and Source Localization

Front Neurosci. 2021 Jan 13:14:620723. doi: 10.3389/fnins.2020.620723. eCollection 2020.

Authors

Christine Ida Hucke¹, Rebekka Margret Heinen², Marlene Pacharra³, Edmund Wascher⁴, Christoph van Thriel¹

Affiliations

¹ Department of Toxicology, Neurotoxicology and Chemosensation, Leibniz Research Centre for Working Environment and Human Factors at the TU Dortmund, Dortmund, Germany.
² Department Neuropsychology, Institute of Cognitive Neuroscience, Ruhr-University Bochum, Bochum, Germany.
³ MSH Medical School Hamburg, University of Applied Sciences and Medical University, Hamburg, Germany.
⁴ Department of Ergonomics, Leibniz Research Centre for Working Environment and Human Factors at the TU Dortmund, Dortmund, Germany.

Abstract

The neuronal cascade related to the perception of either purely olfactory or trigeminal airborne chemicals has been investigated using electroencephalography (EEG) microstate analyses and source localization. However, most airborne chemicals are bimodal in nature, encompassing both properties. Moreover, there is an ongoing debate regarding whether there is one dominant nostril, and this could be investigated using these multichannel EEG methods. In this study, 18 right-handed, healthy participants (13 females) were monorhinally stimulated using an olfactometer with the bimodal component acetic acid during continuous EEG recording. Participants indicated the side of stimulation, the confidence in their decision, and rated the strength of the evoked perception. EEG microstate clustering determined four distinct maps and successive backfitting procedures, and source estimations revealed a network that evolved from visual-spatial processing areas to brain areas related to basic olfactory and trigeminal sensations (e.g., thalamus, cingulate cortex, insula, parahippocampal, and pre-/post-central gyri) and resulted in activation of areas involved in multisensory integration (e.g., frontal-temporal areas). Right-nostril stimulation was associated with faster microstate transition and longer involvement of the superior temporal gyrus, which was previously linked to chemical localization and provides evidence for a potential nostril dominance. The results describe for the first time the processing cascade of bimodal odor perception using microstate analyses and demonstrate its feasibility to further investigate potential nostril dominance.

Keywords: EEG; bimodal odors; lateralization; microstates; source localization.