Tsugaya, S.; Nakamura, A.; Nomura, T.

Recent EEG studies of human quiet stance have identified beta-band event-related desynchronization (beta-ERD) and synchronization (beta-ERS; post-movement beta rebound) during the micro-fall and micro-recovery phases of postural sway, respectively. These modulations correlate with the activation and inactivation of calf muscle activity, supporting an intermittent control strategy that exploits the stable manifolds of the body at unstable equilibrium. However, the neural origin of this sway-related beta rhythmogenesis remains elusive. Here, we investigated this mechanism using a spiking neural network model of the cortico-basal ganglia-thalamic (CBGT) circuitry integrated with a physical inverted pendulum. In this model, sensory feedback is integrated into the striatum, while the motor cortex executes decisions between dorsiflexion and plantarflexion via competition between neuronal populations following drift-diffusion dynamics. In this framework, the decision time represents the control-off period of the intermittent controller. We found that the simulated EEG exhibited characteristic beta-ERD and beta-ERS only when cortico-striatal synaptic weights were functionally tuned to facilitate intermittent motor selection characterized by distinct decision times. Conversely, continuous control -characterized by immediate antagonistic actions without DT- failed to produce these beta modulations. Further analysis revealed that state-dependent sensory feedback and subthalamic nucleus (STN) activity are critical for generating these oscillations through closed-loop interactions. Our results suggest that CBGT-mediated rhythmic beta activity is a hallmark of intermittent motor selection, providing a computational link between basal ganglia dynamics, cortical oscillations, and postural stability.