Sinoatrial Node Impulses Emerge From Unique Synchronization Processing Solutions of Partially Stochastic Local...

Area of Science:

• Cardiovascular Physiology
• Computational Biology
• Systems Neuroscience

Background:

• The sinoatrial node (SAN) exhibits incessant, spontaneous, and heterogeneous local calcium (Ca²⁺) oscillations (LCOs) within its unique cellular architecture.
• These LCOs are fundamental to the generation of cardiac rhythm.

Purpose of the Study:

• To elucidate the information processing mechanisms by which LCOs generate recurrent, rhythmic global SAN impulses.
• To understand the network dynamics underlying cardiac pacemaking.

Main Methods:

• Application of novel dynamical systems and network analyses to ex vivo mouse SAN Ca²⁺ imaging data.
• Analysis of spatiotemporal patterns and functional connectivity of LCOs.

Main Results:

• SAN Ca²⁺ dynamics showed self-organization of LCOs into regional functional clusters with distinct, stable phases and weak electrical coupling.
• Cluster dynamics were non-equilibrium, transitioning between stable and unstable states.
• Spatiotemporal integration of phase overlaps within the cluster network generated recurrent global Ca²⁺ impulses, influenced by stochasticity and energy transitions.
• Small-world network structure balanced local processing with long-range communication for efficient impulse formation.

Conclusions:

• A novel paradigm for SAN impulse formation based on self-organized LCO network dynamics was proposed.
• This mechanism provides flexibility and reliability for heartbeat regulation.
• Findings enhance understanding of SAN autonomic regulation, arrhythmogenesis, and sick sinus syndrome.