Differential modulation of sensorimotor beta oscillations by beta tACS alone and combined repetitive paired-pulse TMS
Hisato Nakazono1, Akinori Takeda2, Emi Yamada3
1Department of Occupational Therapy, Faculty of Medical Science, Fukuoka International University of Health and Welfare, Fukuoka 814-0001, Japan; Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan.
Background:
Combined stimulation with transcranial alternating current stimulation (tACS) at the beta frequency and repetitive paired-pulse transcranial magnetic stimulation (rPPS) produces different after-effects on cortical excitability in the primary motor cortex (M1) compared with either stimulation alone. Sensorimotor beta oscillations are broadly implicated in resting-state activity, as well as in phasic and sustained movements. However, whether combined stimulation can modulate oscillatory activities remains unclear.
Objective:
To address the effects of combined stimulation on sensorimotor beta oscillations.
Methods:
We applied rPPS pulses synchronized with the peak phase of beta tACS (rPPS-tACS), rPPS with sham tACS (rPPS alone), or tACS without rPPS (tACS alone). Cortico-muscular coherence (CMC), movement-related beta desynchronization (MRBD), post-movement beta rebound (PMBR), and beta power during the resting-state and CMC tasks were measured before and after the intervention to assess their impact on sensorimotor beta oscillations.
Results:
rPPS-tACS increased the CMC and decreased the aperiodic offset. A strong correlation was observed between CMC modulation and beta burst rate in the rPPS-tACS condition. tACS alone increased resting beta power, whereas rPPS alone did not modulate any measurements. Moreover, although rPPS-tACS and tACS alone increased the PMBR, their after-effects emerged at high- and low-beta oscillations, respectively.
Conclusion:
Our results suggest that rPPS-tACS and tACS alone over M1 may modulate distinct neural populations underlying sensorimotor beta oscillations. Our combined stimulation with rPPS and beta tACS may be a useful approach for elucidating the diverse functional roles of these oscillations.
More Related Videos
10:25Simultaneous Transcranial Alternating Current Stimulation and Functional Magnetic Resonance Imaging
Published on: June 5, 2017
12:13Assessing Primary Motor Cortex Excitability and Excitability Modulation by Pairing Transcranial Magnetic Stimulation with Electromyography
Published on: October 7, 2025