Effect of Different Currents for Transcranial Modulation of the Sensorimotor Corticospinal Pathway in Healthy Subjects

N/AEnrolling By InvitationNCT07831525

Hospital de Clinicas de Porto Alegre14 enrolled

Overview

Transcranial modulation of the corticospinal sensorimotor pathway is a promising approach in neuroscientic functions. Among the techniques used, transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS) and the application of random noise current stand out. Objective: To compare the e stimulus, in the EEG frequency bands, on Motor Evoked Potentials (MEP) and on the functional activation of the motor cortex, assessed by Functional Near Infrared Spectroscopy (fNIRS) and pain measurements in healthy subjects subjected to a standardized algogenic stimulus. Subjects and Method: This is a randomized, double-blind, controlled and crossover clinical trial, involving the inclusion of 14 healthy male subjects, with complete secondary education, aged between 18 and 40. years. Participants will be randomized to receive Transcranial Direct Current Stimulation (tDCS), (2) Transcranial Alternating Current Stimulation (tACs), (3) Random Noise Current, (4) Simulated Stimulation Session and (5) Rest Session. Experimental conditions will take place in a standard, quiet and bright room. Assessments will include Motor Evoked Potential, Heat Pain Threshold, Motor Area Activation through metabolic activation measured by fNIRS and analysis of EEG frequency waves. After the baseline assessment, participants will undergo a session of transcranial stimulation, followed by an algogenic stimulus with water at zero degrees, immersion of the dominant hand for 1 minute, with rest intervals of 3 minutes between each of the four serial stimuli. After this stimulus session, outcome measurements will be carried out. Expected results: This clinical trial is expected to provide insights into how tDCS, tACs and random stimulation in to an algogenic stimulus. The results may contribute to the development of therapeutic or neuromodulation strategies in clinical conditions where the regulation of the cortico-spinal sensorimotor pathway is relevant.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

OTHER

Masking

TRIPLE

Interventions

Transcranial Alternating Current StimulationDEVICE

Single session of active gamma transcranial alternating current stimulation delivered for 30 minutes using a battery-powered external stimulator. Stimulation is applied through two sponge electrodes (5 × 7 cm) mounted on a neoprene cap. The stimulation frequency is 40 Hz, based on previous gamma-band transcranial alternating current stimulation (tACS) studies. The anode is positioned at C3 (left primary motor cortex, M1), and the cathode over the ipsilateral clavicular region.

Transcranial Direct Current StimulationDEVICE

Stimulation is delivered using two sponge electrodes (5 × 7 cm) mounted on a neoprene cap. The electrodes are positioned on the scalp according to the international 10-20 system. The anode is placed at position C3 (left primary motor cortex, M1) and the cathode over the ipsilateral clavicular region. The sinusoidal current intensity per channel ranges from ±2 mA. The session duration is 20 minutes.

Transcranial Random Noise Stimulation (tRNS)DEVICE

Stimulation is delivered using two sponge electrodes mounted on a neoprene cap. The anode is positioned at C3 (left primary motor cortex, M1), and the cathode over the ipsilateral clavicular region. A random current level is generated for each sample at a sampling rate of 1280 samples per second. The random values are normally distributed, following a bell-shaped probability density function. The noise signal contains all frequencies up to half the sampling rate (maximum 640 Hz) and has no DC offset.

Sham StimulationDEVICE

During the sham stimulation session, the tDCS device ramps up the current to 2 mA over 30 seconds and then is immediately turned off. This procedure mimics the sensations of active stimulation without delivering therapeutic current for the remainder of the session.

Eligibility

Sex: MALEMin age: 18 YearsMax age: 45 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Healthy male subjects aged 18-45 years, with at least a high school diploma, and not engaged in night-shift work. Exclusion Criteria: * Contraindications to transcranial stimulation include implanted medical devices in the brain, cardiac pacemakers, and cochlear implants. * Current use of psychotropic medications. * History of alcohol or substance abuse within the past 6 months. * Neurological disorders, history of traumatic brain injury, or prior neurosurgery. * Beck Depression Inventory-II (BDI-II) score \>13. * Self-Reporting Questionnaire (SRQ) score \>7.

Outcomes

Primary Outcomes

Resting-State EEG Power Spectra Across Frequency Bands (Delta, Theta, Alpha, Beta 1, Beta 2, and Gamma)

Electroencephalography (EEG) will be used to quantify neuronal activity through quantitative EEG (qEEG) analysis. Resting-state EEG power spectra will be analyzed across delta, theta, alpha, beta, and gamma frequency bands, reflecting synchronized neuronal oscillations. EEG data will be recorded using a 20-electrode montage according to the international 10-20 system during an 8-minute resting-state paradigm with alternating eyes-open and eyes-closed conditions. Cortical source localization will be performed using standardized Low-Resolution Brain Electromagnetic Tomography (sLORETA).