How does intracellular Ca2+ oscillate: by chance or by the clock?
Ca2+ oscillations have been considered to obey deterministic dynamics for almost two decades. We show for four cell types that Ca2+ oscillations are instead a sequence of random spikes. The standard deviation of the interspike intervals (ISIs) of individual spike trains is similar to the average ISI; it increases approximately linearly with the average ISI; and consecutive ISIs are uncorrelated. Decreasing the effective diffusion coefficient of free Ca2+ using Ca2+ buffers increases the average ISI and the standard deviation in agreement with the idea that individual spikes are caused by random wave nucleation. Array-enhanced coherence resonance leads to regular Ca2+ oscillations with small standard deviation of ISIs.
Skupin
Alexander
A
Department of Theoretical Physics, Hahn Meitner Institut, Berlin, Germany.
Kettenmann
Helmut
H
Winkler
Ulrike
U
Wartenberg
Maria
M
Sauer
Heinrich
H
Tovey
Stephen C
SC
Taylor
Colin W
CW
Falcke
Martin
M
D000200:Action Potentials; D000818:Animals; D001703:Biophysics / Q000379:methods*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D002462:Cell Membrane / Q000378:metabolism*; D004058:Diffusion; D004594:Electrophysiology / Q000379:methods; D006801:Humans; D008954:Models, Biological; D009474:Neurons; D009991:Oscillometry; D013269:Stochastic Processes
D002118:Calcium