Short excitatory projections promote burst activity and modular functional organization in neural networks

Abstract Physical constraints in the brain favor short, distance-dependent connections. How-ever, short-range projections are not merely a compromise imposed by these constraints; they also serve essential functional roles. Here, we explore networks with balanced excitation and inhibition, demonstrating that short excitatory projections fundamentally increase the number of common presynaptic inputs, thereby enhancing the correlations of neural responses. Strengthened recurrent correlations can lead to bursting states, amplifying postsynaptic neuronal activity and supporting signal propagation over long distances within the network. Moreover, even without an explicitly imposed modular structure, short excitatory connections can give rise to functional clustering and support a broad spectrum of modular functions. Therefore, this structural principle provides a mechanistic basis for functional column formation and dynamic burst propagation, suggesting that the brain transforms structural wiring constraints into opportunities for complex computation and distributed processing. These findings pave the way for a deeper understanding of how the brain transforms structural limitations into opportunities for complex computation.