The neural topologies that orchestrate movement

Salif Axel Komi, Postdoctoral Researcher, Department of Neuroscience, University of Copenhagen, Denmark

Locomotion is a complex behavior orchestrated by neural mechanisms that span from individual neuronal identities to large-scale network dynamics. Our study capitalizes on the synergy between experimental observations and computational modeling to delineate these mechanisms. First, we explore how population dynamics shape behavioral states through the analysis of neuronal spiking from freely moving rodents' spinal cords. Our analysis reveals that during locomotion, neuronal populations exhibit ring-like limit cycle dynamics, while during arrest, the network converges toward stable fixed points of the state-space—features that underpin the stability and flexibility of movement control. In conjunction with these empirical findings, we propose a novel model of the spinal cord that captures these dynamics as emergent properties inherent to its spatial organization. Central to this model is an asymmetric "Mexican hat" connectivity—characterized by local excitation with distal inhibition — arising from the spatial organization of cell types, identified in single-cell RNA sequencing and spatial transcriptomics data. This spatial structuring supports the formation and propagation of motor rhythms without extensive parameter tuning. We propose an integrated framework wherein spatial organization informs both cellular connectivity and dynamic neural coding. Hence, our approach allows bridging single neuron identities to circuit-level phenomena, which can offer a comprehensive perspective on the neural basis of movement.