Phase resetting of the mammalian circadian clock relies on a rapid shift of a small population of pacemaker neurons

The circadian pacemaker of the suprachiasmatic nuclei (SCN) contains a major pacemaker for 24 h rhythms that is synchronized to the external light-dark cycle. In response to a shift in the external cycle, neurons of the SCN resynchronize with different pace. We performed electrical activity recordin...

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Bibliographic Details
Published in:PloS one 2011-09, Vol.6 (9), p.e25437-e25437
Main Authors: Rohling, Jos H T, vanderLeest, Henk Tjebbe, Michel, Stephan, Vansteensel, Mariska J, Meijer, Johanna H
Format: Article
Language:English
Subjects:
Animals
Biological clocks
Biology
Circadian Clocks - physiology
Circadian rhythm
Circadian rhythms
Comparative analysis
Curve fitting
Electrophysiology
Gene expression
Laboratories
Light
Male
Mammals
Microscopy
Neurons
Neurons - cytology
Neurons - physiology
Phase distribution
Polypeptides
Predictions
Quantitative analysis
Rats
Rats, Wistar
Rodents
Subpopulations
Suprachiasmatic Nucleus - cytology
Synchronism
Synchronization
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Summary:The circadian pacemaker of the suprachiasmatic nuclei (SCN) contains a major pacemaker for 24 h rhythms that is synchronized to the external light-dark cycle. In response to a shift in the external cycle, neurons of the SCN resynchronize with different pace. We performed electrical activity recordings of the SCN of rats in vitro following a 6 hour delay of the light-dark cycle and observed a bimodal electrical activity pattern with a shifted and an unshifted component. The shifted component was relatively narrow as compared to the unshifted component (2.2 h and 5.7 h, respectively). Curve fitting and simulations predicted that less than 30% of the neurons contribute to the shifted component and that their phase distribution is small. This prediction was confirmed by electrophysiological recordings of neuronal subpopulations. Only 25% of the neurons exhibited an immediate shift in the phase of the electrical activity rhythms, and the phases of the shifted subpopulations appeared significantly more synchronized as compared to the phases of the unshifted subpopulations (p
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0025437