Explosive synchronization in Chialvo neuronal network: Roles of chemical, electrical, and hybrid coupling

Explosive synchronization represents an abrupt and hysteretic transition to collective neural activity and has been linked to sudden functional changes in brain dynamics. In this work, we systematically investigate how different synaptic mechanisms shape explosive synchronization in heterogeneous networks of Chialvo neurons. By comparing electrical, chemical, and hybrid synaptic interactions, we reveal pronounced qualitative differences in their synchronization behavior. Our results show that electrical coupling robustly supports explosive synchronization across a wide range of conditions, whereas chemical synapses exhibit a significantly lower probability of explosive transitions and reduced hysteresis. Neuronal heterogeneity enhances explosiveness under electrical coupling but suppresses it in chemically coupled networks. We further demonstrate that synaptic reversal potential plays a decisive role: fully inhibitory chemical networks fail to synchronize, while increasing excitatory drive lowers the synchronization threshold and weakens bistability. Synaptic delay introduces additional control, enabling both explosive and continuous transitions depending on its value. In hybrid networks, intermediate ratios of electrical and chemical coupling eliminate explosive synchronization altogether, yielding smooth and reversible transitions. Finally, increasing connectivity density progressively destroys explosive synchronization, with chemical synapses showing much higher sensitivity to topology than electrical ones.