A Cortico-Basal Ganglia-Thalamic Network Model Linking Intermittent Postural Control to Sway-Related Beta-Band...

Electroencephalographic (EEG) studies of human quiet stance demonstrate beta-band event-related desynchronization (beta-ERD) during the micro-fall phase of postural sway, followed by event-related synchronization (beta-ERS; post-movement beta rebound) during the micro-recovery phase. These modulations correlate with intermittent ankle muscle inactivation that exploits the stable manifolds of an unstable upright equilibrium; however, how such sway-related beta dynamics arise within closed-loop brain-body interactions remains unclear. Here, we investigated a possible circuit-level account of these dynamics using an embodied spiking neural network model of the cortico-basal ganglia-thalamic (CBGT) circuitry integrated with an inverted pendulum. In this closed-loop system, continuous sensory feedback is integrated into the striatum, while the motor cortex executes decisions via drift-diffusion-like population competition, where decision time (DT) represents the intermittent control-off period. We demonstrate that simulated cortical LFPs exhibit characteristic sway-phase-locked beta-ERD and beta-ERS when corticostriatal synaptic weights are functionally balanced to implement intermittent control. Conversely, a forced-choice continuous-like regime that ceaselessly generates feedback torque fails to replicate these modulations, sustaining flat network states devoid of control-off periods (DT). Structural dissections show that, within the model, disrupting bidirectional thalamocortical loops or the GPe-STN circuit abolishes sway-phase-locked beta modulation, despite continuous sensory drive. Our findings provide a computational account linking sway-phase-locked beta activity to intermittent motor selection within the proposed CBGT framework. This closed-loop modeling framework offers a testable candidate account for how alterations in brain-body dynamics may jointly affect behavioral intermittency and beta-band modulation, with potential relevance to postural impairments in Parkinson's disease.