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Frequency-Dependent Effects of Transcranial Photobiomodulation on Cortical Excitability
Sponsor: Hospital de Clinicas de Porto Alegre
Summary
This study aims to investigate the frequency-dependent effects of near-infrared (NIR) transcranial photobiomodulation (tPBM) on human cortical excitability and fine motor performance. A cohort of 20 healthy adult volunteers (aged 18-35 years) will participate in a randomized, double-blind, sham-controlled, single-center study utilizing a within-subject, five-arm crossover design. Each participant will undergo five distinct experimental conditions separated by a strict washout period: active Continuous Wave (CW) tPBM, active pulsed tPBM at three neural oscillation frequencies (10 Hz, 40 Hz, and 100 Hz), and an inactive Sham comparator. All interventions will be delivered using a clinical-grade near-infrared device. To isolate the specific effects of pulse frequency from overall energy delivery, the total energy dose (cumulative Joules) and total exposure time will be held perfectly constant across all active arms. The pulsed conditions will keeps the average irradiance and cumulative fluence identical to the continuous wave mode. Cortical excitability will be assessed via single- and paired-pulse Transcranial Magnetic Stimulation (TMS) protocols over the primary motor cortex (M1). Fine motor performance will be quantified using a smartphone-based Finger Tapping Test (FTT). Safety and systemic parameters will be tracked using the Systematic Assessment for Treatment Emergent Events - Systematic Inquiry (SAFTEE-SI) and vital signs. The central hypothesis is that distinct modulation frequencies will differentially influence corticospinal excitability and motor execution, independent of the total energy delivered.
Official title: Frequency-Dependent Effects of Transcranial Photobiomodulation on Cortical Excitability and Fine Motor Performance: A Randomized, Double-Blind, Sham-Controlled, Crossover Trial
Key Details
Gender
All
Age Range
18 Years - 35 Years
Study Type
INTERVENTIONAL
Enrollment
20
Start Date
2026-07
Completion Date
2027-10
Last Updated
2026-07-16
Healthy Volunteers
Yes
Interventions
Transcranial Photobiomodulation
Transcranial photobiomodulation (tPBM) is a non-invasive, non-thermal neuromodulatory modality that utilizes low-power coherent (laser) or non-coherent (light-emitting diodes, LEDs) light sources within the red (lambda = 600-700 nm) and near-infrared (NIR; lambda = 700-1100 nm) spectral windows to modulate cortical function. Structurally tailored to penetrate superficial anatomical barriers-including the scalp, skull, and meninges-tPBM delivers photons directly to the cerebral cortex.
Locations (1)
Hospital de Clínicas de Porto Alegre
Porto Alegre, Rio Grande do Sul, Brazil