Coherence-incoherence patterns in coupled excitable systems

Excitability is a fundamental dynamical paradigm underlying both local and collective activity across a broad range of living systems, from neurons and cardiomyocytes to pancreatic β-cells, cancer cells, and the emerging field of network physiology. This review summarizes the current state of research on coherence-incoherence patterns in coupled excitable systems, covering theoretical advances and experimental evidence for their roles in physiological and pathological processes. Particular emphasis is placed on how excitable dynamics modifies the mechanisms of pattern formation relative to coupled oscillator networks, highlighting the importance of inhibitory/repulsive interactions and the constructive role of noise through phenomena such as coherence resonance, in generating pattern classes characteristic of excitable media, including bumps, patched patterns, and noise-facilitated chimera states. We further discuss how existing theoretical concepts can be extended to biological systems characterized by heterogeneous local dynamics, complex coupling architectures, and metastable behavior. In addition, we survey state-of-the-art electrophysiological and optical imaging techniques for observing coherence-incoherence patterns and assess current evidence linking them to sleep, cognition, spatial navigation, epilepsy, cardiac arrhythmia, pancreatic islet dynamics, and cancer progression. Finally, we outline major open challenges, including characterization of chaos, long-term dynamics and finite-size effects, experimental validation, control of pattern emergence/termination and switching, and the development of biologically realistic theoretical frameworks.