Can brain stimulation enhance the effects of laser acupuncture on movement and brain activity?

This study involves the combined use of laser acupuncture and transcranial direct current stimulation (tDCS) to investigate their effects on brain excitability and motor threshold. Laser Acupuncture Therapy Laser acupuncture is a non-invasive therapeutic method that applies low-level laser therapy (LLLT) to acupuncture points to stimulate physiological responses. In this study, a low-level laser device will be used to irradiate the LI4 (Hegu) and LI11 (Quchi) acupoints bilaterally. The parameters for laser acupuncture are: Wavelength: 808 nm Power output: 100 mW Energy density: 4 J/cm² per point Mode: Continuous wave Duration: 5 minutes Transcranial Direct Current Stimulation (tDCS) tDCS is a non-invasive neuromodulation technique that delivers a constant, low-intensity electrical current to the scalp to modulate neuronal excitability. In this study, anodal tDCS will be applied over the primary motor cortex (M1), with the cathode placed over the contralateral supraorbital region. The stimulation parameters are: Intensity: 2 mA Duration: 20 minutes Electrode size: 5x7 cm (35 cm²) Current density: 0.043 mA/cm² Timing and Delivery: Laser acupuncture and tDCS will be administered simultaneously, with both interventions starting and ending at the same time. Frequency and Duration: Each participant will receive one session per condition, and there are three conditions in total (e.g., laser acupuncture alone, tDCS alone, and combined intervention), following a crossover design. Each session lasts approximately 120 minutes including setup and assessments. A washout period of at least 48 hours will be implemented between sessions to minimize carryover effects. Personnel: All interventions will be administered by a trained acupuncturist with experience in laser therapy, and a trained neurostimulation technician for tDCS procedures. Setting: All sessions will take place in a controlled university research laboratory at Monash University Peninsula Campus. Adherence and Fidelity Monitoring: Intervention adherence will be monitored by trained research staff using standardized treatment checklists. Fidelity to the protocol will be ensured through direct observation and regular supervision. Equipment logs will be maintained to record parameters and duration for each session.

This study investigates the combined effects of low-intensity laser therapy applied to acupoints and transcranial direct current stimulation (tDCS) on corticospinal excitability and sensorimotor function. Laser Therapy Applied to Acupoints Low-intensity laser stimulation was delivered using a gallium–aluminum–arsenide (GaAlAs) laser device. The laser was applied simultaneously to the right LI4 (Hegu) and LI10 (Shousanli) acupoints. The stimulation parameters were as follows: Wavelength: 655 nm Output power: 50 mW per point Energy dose: 7.5 J per point Mode: Continuous wave Beam divergence: 0.0157 rad Duration: 5 minutes In sham laser conditions, the probe was positioned identically without light emission. To maintain masking, both participants and the operator wore protective goggles during all laser procedures. Transcranial Direct Current Stimulation (tDCS) tDCS was delivered using saline-soaked sponge electrodes. The anode (5 × 7 cm²) was positioned over the primary motor cortex (M1), and the cathode (3 × 4 cm²) was placed over the contralateral supraorbital region. Stimulation parameters were: Intensity: 2 mA Duration: 20 minutes Sham tDCS consisted of a 30-second ramp-up and ramp-down period at the beginning of stimulation, followed by no current for the remainder of the session. Timing and Delivery All sessions lasted 20 minutes. Laser stimulation was applied during the first 5 minutes of the session, concurrently with tDCS when applicable. Study Design and Session Structure This study employed a randomized, sham-controlled, crossover design with four conditions: Active laser + sham tDCS Active tDCS + sham laser Combined active laser + active tDCS Double sham Each participant completed all conditions in a counterbalanced order, with a washout period of at least 48 hours between sessions to minimize carryover effects. Each session lasted approximately 120 minutes, including setup, stimulation, and outcome assessments.