Recent brain connectome studies have evidenced distinct and overlapping brain regions involved in processing olfactory perception. However, neural correlates of hypo- or anosmia in olfactory disorder patients are poorly known. Furthermore, the bottom-up and top-down processing of olfactory perception have not been well-documented, resulting in difficulty in locating the disease foci of olfactory disorder patients. The primary aim of this study is to characterize the bottom-up process of the neural dynamics across peripheral and central brain regions in anesthetized mice. We particularly focused on the neural oscillations of local field potential (LFP) in olfactory epithelium (OE), olfactory blub (OB), prefrontal cortex (PFC), and hippocampus (HC) during an olfactory oddball paradigm in urethane anesthetized mice. Odorant presentations evoked neural oscillations across slow and fast frequency bands including delta (1–4 Hz), theta (6–10 Hz), beta (15–30 Hz), low gamma (30–50 Hz), and high gamma (70–100 Hz) in both peripheral and central nervous systems, and the increases were more prominent in the infrequently presented odorant. During 5 s odorant exposures, the oscillatory responses in power were persistent in OE, OB, and PFC, whereas neural oscillations of HC increased only for short time at stimulus onset. These oscillatory responses in power were insignificant in both peripheral and central regions of the ZnSO4-treated anosmia model. These results suggest that olfactory stimulation induce LFP oscillations both in the peripheral and central nervous systems and suggest the possibility of linkage of LFP oscillations in the brain to the oscillations in the peripheral olfactory system.
Bibliographical noteFunding Information:
This research was supported by the grant from the Korea Mouse Phenotyping Project (2016M3A9D5A01952414) of the Ministry of Science and Information and Communication Technology (ICT) through the National Research Foundation (NRF), by the Global Research Lab (GRL). Program of the NRF funded by Ministry of Science, Information, and Communication Technologies and Future Planning (2016K1A1A2910779), by the grant from the NRF of Korea funded by the Korea government (2017R1A2B3012659), and by the grant from the National Research Council of Science and Technology of Korea on the Project for the Development of Solutions for the Diagnosis, Treatment and Care System of Dementia (No. CRC-15-04-KIST).
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