title: Synchronous circadian voltage rhythms with asynchronous calcium rhythms in the suprachiasmatic nucleus.
abstract: The suprachiasmatic nucleus (SCN), the master circadian clock, contains a network composed of multiple types of neurons which are thought to form a hierarchical and multioscillator system. The molecular clock machinery in SCN neurons drives membrane excitability and sends time cue signals to various brain regions and peripheral organs. However, how and at what time of the day these neurons transmit output signals remain largely unknown. Here, we successfully visualized circadian voltage rhythms optically for many days using a genetically encoded voltage sensor, ArcLightD. Unexpectedly, the voltage rhythms are synchronized across the entire SCN network of cultured slices, whereas simultaneously recorded Ca2+rhythms are topologically specific to the dorsal and ventral regions. We further found that the temporal order of these two rhythms is cell-type specific: The Ca2+rhythms phase-lead the voltage rhythms in AVP neurons but Ca2+and voltage rhythms are nearly in phase in VIP neurons. We confirmed that circadian firing rhythms are also synchronous and are coupled with the voltage rhythms. These results indicate that SCN networks with asynchronous Ca2+rhythms produce coherent voltage rhythms.
authors.affiliation: Photonic Bioimaging Section, Research Center for Cooperative Projects, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan; enoki@pop.med.hokudai.ac.jp.|Department of Chronomedicine, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan.|Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Saitama 332-0012, Japan.
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Enoki
authors.affiliation: Photonic Bioimaging Section, Research Center for Cooperative Projects, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan.|Department of Chronomedicine, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Oda
authors.affiliation: Department of Molecular Neuroscience and Integrative Physiology, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Ishikawa 920-8640, Japan.
authors.forename: Michihiro
authors.initials: M
authors.lastname: Mieda
authors.affiliation: Photonic Bioimaging Section, Research Center for Cooperative Projects, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Ono
authors.affiliation: Department of Chronomedicine, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan.
authors.forename: Sato
authors.initials: S
authors.lastname: Honma
authors.affiliation: Department of Chronomedicine, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan.
authors.forename: Ken-Ichi
authors.initials: KI
authors.lastname: Honma
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002940:Circadian Rhythm; D005260:Female; D008297:Male; D008564:Membrane Potentials; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000378:metabolism; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000378:metabolism*
chemical_list: D002118:Calcium
keywords: circadian rhythm; intracellular calcium; membrane potential; neuronal network; time-lapse imaging