Cortical Beta Oscillations Contributing to Precision Stepping at Gait Initiation.

Precision step control during gait initiation is essential for stable locomotion. This study examined the role of the central nervous system in this process. In Experiment 1, 14 healthy young adults (21.9 ± 0.9 years) performed a control task (normal gait initiation) and a precision task (targeted foot placement with the first step). Task movements were divided into three phases: planning, preparation, and swing. Event-related desynchronization (ERD) in the alpha and beta bands (α-ERD and β-ERD) was calculated at Fz, Cz, and Pz for each phase. Step accuracy was evaluated as the outcome measure. In Experiment 2, 10 healthy young adults (22.1 ± 0.8 years) received 30-Hz transcranial alternating current stimulation (tACS) targeting the primary motor cortex, using a randomized crossover design consisting of active and sham stimulation conditions, to modulate β-ERD. Δβ-ERD and Δstep accuracy were calculated as the difference between post- and pre-stimulation values. In Experiment 1, a significant interaction effect was observed for ERD. Greater β-ERD during the preparation phase of the precision task was observed compared with the control task. Reduced β-ERD at Cz was significantly correlated with better step accuracy. In Experiment 2, no significant stimulation × time interaction was observed for β-ERD or step accuracy, and no significant correlation was found between Δβ-ERD and Δstep accuracy following tACS. These results indicate a close relationship between β-ERD in the sensorimotor cortex and step accuracy, suggesting that beta-band cortical activity plays an important role in precision stepping.