Multiscale emergence of directional traveling waves in random neuronal networks with nonreciprocal excitation-inhibition synaptic coupling.

Abstract

Traveling waves (TWs) are a fundamental mechanism of large-scale spatiotemporal coordination in the cortex, yet how their directionality originates from microscale circuit properties remains an open question. To address this, we introduce a multiscale model that reveals a dual emergence process underlying cortical TW dynamics. We show that local nonreciprocal excitation-inhibition (E-I) coupling generically produces sustained collective oscillations. These oscillations serve as building blocks for macroscopic waves: when spatially coupled, they give rise to large-scale spatiotemporal patterns whose propagation direction is determined by emergent frequency gradients. Crucially, these frequency gradients-and therefore the wave propagation direction-can be controlled by intrinsic network properties (e.g., E-I coupling gradients) and extrinsic input. Our model reproduces the diversity of experimentally observed TW behaviors, including both fixed-direction and task-responsive propagation. Furthermore, the system exhibits robust wave formation even under fluctuating external input, mirroring biological reliability. By linking synaptic-level architecture to large-scale wave dynamics, our work establishes a mechanistic, multiscale foundation for the emergence and control of cortical TWs, with broader implications for neural computation and nonreciprocal wave-metamaterials.