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| Poster #268 Olfactory bulb theta oscillations in the absence of theta-range sniffing |
| Andrew Sheriff1, Gregory Lane1, Qiaohan Yang1, Naelly Arriaga1, Guangyu Zhou1, Mahmoud Omidbeigi1, Vivek Sagar1, Leslie M. Kay2, Bruce Tan3, Christina Zelano1 1Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States 2Department of Psychology, Institute for Mind and Biology, University of Chicago, Chicago, IL, United States 3Department of Otolaryngology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States |
In rodents, olfactory bulb theta oscillations (4–12 Hz) are largely locked to fast, theta-range sniffing rhythms. As a result, olfactory neural representations are defined by sniffing, which provides a temporal framework for odor processing. Rodent sniffing behavior is dynamic, modulated by learning and behavioral state, and directly impacts temporal processing windows in the olfactory system. Thus sniffing provides a direct link between behavior and neural activity, and is an integral aspect of odor coding mechanisms in the brain. Despite the fundamental link between sniffing behavior, theta oscillations, and neural representations of odor in rodents, the presence and function of theta oscillations in the human olfactory bulb remain uninvestigated. Human olfactory processing occurs under vastly different temporal constraints: humans sniff at rates far slower than rodents, raising questions about the applicability of these principles to human olfactory circuits. Since rodent studies demonstrate a direct relationship between sniff-driven oscillations and neural coding, the absence of theta-range sniffing in humans necessitates research into whether the human olfactory bulb operates under similar mechanisms. Without rhythmic sampling in the theta range, does the human olfactory bulb still generate theta oscillations that create a temporal structure for odor responses? Here we will explore this question by combining olfactory bulb recordings with sniffing tasks in humans. Preliminary results from 4 participants suggest that both intentional sniffing and odor drive theta oscillations in the human olfactory bulb, and that this theta rhythm organizes a strikingly consistent, odor-induced gamma oscillation centered around 54 Hz. |