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Sparks and waves in a stochastic fire-diffuse-fire model of Ca2+ release
1Department of Mathematical Sciences, Loughborough University, Leicestershire, LE11 3TU, United Kingdom. S.Coombes@lboro.ac.uk
Summary
This study models calcium ion signaling, revealing how random calcium release events (sparks) can spontaneously form waves. Introducing noise creates a phase transition, enabling wave propagation or synchronized release from all stores.
Area of Science:
- Cellular Biology
- Biophysics
- Computational Neuroscience
Background:
- Calcium ions act as crucial second messengers in cellular processes.
- Calcium waves, formed by elementary release events (puffs/sparks), are of significant experimental interest.
- Understanding the mechanisms governing calcium wave formation and propagation is essential.
Purpose of the Study:
- To develop a computationally efficient model for calcium release.
- To investigate the role of stochasticity and noise in calcium signaling.
- To analyze the transition between propagating and abortive calcium wave structures.
Main Methods:
- A stochastic generalization of the fire-diffuse-fire threshold model was developed.
- The model incorporates discrete calcium stores and release probability through threshold noise.
- Numerical simulations were used to observe calcium spark production and wave formation.
Main Results:
- Stochastic calcium release spontaneously generates calcium sparks that can merge into saltatory waves.
- A critical noise level was identified, leading to a nonequilibrium phase transition between propagating and abortive structures.
- The observed transition aligns with models in the directed percolation universality class.
Conclusions:
- Threshold noise is a key factor in generating and controlling calcium wave dynamics.
- The model provides insights into how noise can induce synchronized cellular behavior (coherence resonance).
- This work offers a simplified yet powerful framework for studying complex calcium signaling phenomena.