title: Fast synchronous oscillations of firing rate in cultured rat suprachiasmatic nucleus neurons: possible role in circadian synchronization in the intact nucleus.
abstract: The coherent circadian rhythm of the brain's master circadian pacemaker, the suprachiasmatic nucleus (SCN), is a result of synchronization of electrical activity of many SCN neurons possessing their own circadian oscillators. However, how the activity of these neurons is synchronized is not precisely known. By plotting the electrical firing rates of dispersed rat SCN neurons in multi-electrode array dishes with 20-s averaging of action-potential activity, we have investigated a novel phenomenon: fast (relative to the circadian cycle) oscillations of firing rate (FOFR) with duration of bursts ∼10min and interburst interval varying in a range from 20 to 60min in different cells, remaining nevertheless rather regular in individual cells. In many cases, separate neurons in distant parts of the 1mm recording area of an array exhibited correlated FOFR. FOFR of individual cells were positively or negatively correlated with those of other cells in a functioning neural network. Intriguingly, in occasional neuron pairs, transformation of their irregular firing to circadian peaks was accompanied by appearance of FOFR and an increase in the magnitude of firing correlation. We hypothesize that this FOFR observed in cultured SCN neurons contribute to synchronization of the circadian rhythm in the intact SCN.
authors: Department of General Physiology of Nervous System, Institute of Physiology, 4, Bogomoletz str., Kiev 01024, Ukraine. NI.Kononenko@gmail.com
authors: Nikolai I
authors: NI
authors: Kononenko
authors: Sato
authors: S
authors: Honma
authors: Ken-Ichi
authors: K
authors: Honma
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001683:Biological Clocks / Q000502:physiology; D002478:Cells, Cultured; D002940:Circadian Rhythm / Q000502:physiology*; D008839:Microelectrodes; D009415:Nerve Net / Q000166:cytology / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D018408:Patch-Clamp Techniques / Q000295:instrumentation / Q000379:methods*; D051381:Rats; D017208:Rats, Wistar; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000473:pathology / Q000502:physiology*; D013997:Time Factors