Detection of circadian rhythm disturbance of carbachol-induced beta wave dynamics in rat hippocampal slices using neural networks

Abstract

Rats exhibit a circadian rhythm of locomotor activity. Recently, the relation between circadian rhythm and memory has been elucidated. Brain waves are related to memory processes and are modulated by circadian rhythm. Beta wave-like oscillations within 13–30 Hz can be induced by using carbachol, a cholinergic agonist, in rat hippocampal slices. In this study, we prepared hippocampal slices from rats maintained under light/dark (LD) or dark/dark (DD) conditions. We previously reported that carbachol-induced beta oscillations (CIBO) appeared at all times of the day, and oscillatory parameters, such as duration and inter-burst intervals, demonstrated significant diurnal changes. We also studied whether the time of day can be predicted using CIBO parameters and whether circadian disturbances can be detected with these parameters. Using CIBO parameters, a higher accuracy rate was obtained for time-of-day prediction than that when using the amount of locomotor activity during the day. The time of day was not correctly predicted when the parameters were applied under the DD condition, using the CIBO-parameter-trained neural network under LD conditions. Using the oscillatory parameters of the brain waves induced in the neuronal circuit will estimate the internal subjective time of the day and detect circadian disturbances such as DD condition. (199 words).

KEYWORDS:

• Hippocampus
• brain wave
• circadian rhythm
• neural network
• circadian disturbances

Acknowledgements

This work was supported by the Japan Society for the Promotion of Science KAKENHI, under grants 20650094, 16H06534, and 20K20828.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by JSPS [grant number 20650094, 16H06534 and 20K20828].

Notes on contributors

Masaya Shigemoto

Masaya Shigemoto (No member)

Masaya Shigemoto received his BS degree in engineering from the Kyushu Institute of Technology in 2018. He was a researcher at the Kyushu Institute of Technology and engaged in research on the circadian rhythm and electrophysiology of the rat hippocampus. He is currently an assistant professor at the Information Science and Technology Department, National Institute of Technology, Oshima College, Japan.

Kiyohisa Natsume

Kiyohisa Natsume (Member)

Kiyohisa Natsume received his BS degree in pharmacy from the University of Tokyo in 1987, MS degree in pharmacy from the University of Tokyo in 1989, and PhD in pharmacy from the University of Tokyo in 1993. He was an associate professor at the Kyushu Institute of Technology in 2001 and a professor at Kyushu Institute of Technology since 2006. He is currently engaged in research on EEG and brain–computer interfaces using animals.