Effects of Transcranial Electrical Stimulation on Task Performance in Healthy Adults (BRAIN-STIM)

Preliminary Investigations of Transcranial Electrical Stimulation Effects on Neurophysiology and Behavior

The objective of this randomized, double-blind, sham-controlled, crossover study is to evaluate the effects of transcranial electrical stimulation (tES) on complex cognitive task performance in healthy adult volunteers.

The primary questions this study aims to answer are:

1. Does tES improve task performance, including speed, accuracy, and overall success, during a computerized track-and-capture task?
2. Do different stimulation targets produce differential effects on performance?
3. Are there short-term post-stimulation effects on task performance (up to 48 hours)?

Participants will:

1. Complete two testing sessions under either active or sham stimulation conditions.
2. Perform a complex operational task involving dual-hand controllers while undergoing tES or sham stimulation, and immediately after.
3. Return for follow-up task performance assessments at 24 and 48 hours post-stimulation to evaluate after-effects.

Study Overview

• Status: Completed
• Conditions: Healthy; Cognition; Brain Stimulation; Neurophysiology; Transcranial Direct Current Stimulation (tDCS); Psychomotor Performance
• Intervention / Treatment: Device: Active Transcranial Electrical Stimulation; Device: Sham Transcranial Electrical Stimulation

Detailed Description

Transcranial electrical stimulation (tES) is a non-invasive neuromodulation technique that delivers low-intensity electrical currents (e.g., <2 mA) through scalp electrodes to modulate brain activity. Numerous studies have shown that tES can enhance cognitive functions such as learning, memory, attention, and decision-making in healthy individuals, as well as provide therapeutic benefits in psychiatric and neurological populations. Despite these findings, substantial knowledge gaps remain regarding the effects of tES, particularly in the context of complex, operationally relevant tasks.

Existing research has primarily focused on the effects of tES on simple cognitive tasks, with limited investigation into task that require multiple cognitive domain to operate simultaneously. Performance on complex tasks, such as those involving motor coordination, visual-spatial process, decision-making, and rapid response, may respond differently to tES than simple, isolated tasks. Understanding these effects could have broad applications in optimizing cognitive performance across various high-demand settings.

This study is designed to address several key uncertainties:

1. Inter-individual variability in behavioral and neurophysiological responses to tES.
2. the impact of stimulation parameters (location, type, intensity) on task performance.
3. The magnitude and duration of both immediate and post-stimulation effects on behavior.

To investigate these questions, healthy adults perform a computerized track-and-capture task requiring real-time motor control and decision-making using dual-hand controllers. Participants undergo both active and sham stimulation in a randomized, double-blind, crossover design. Stimulation will target either the left dorsolateral prefrontal cortex or the left anterior insula, guided by current flow modeling software. Performance is assessed during stimulation, immediately after, and at 24 and 48 hours post-stimulation to evaluate both immediate and short-term after-effects.

Outcome measures include task performance metrics (e.g., speed, accuracy, overall success) and neurophysiological data collected via non-invasive monitoring with functional near-infrared spectroscopy (fNIRS). The study is part of a broader research effort to characterize the functional impact of tES on complex behavior and to inform future applications in cognitive performance enhancement.

All stimulation procedures follow established safety guidelines for low-intensity tES, including continuous monitoring of electrode impedance and post-session adverse event questionnaires assessing discomfort, mood, and cognitive status. The Soterix Medical MXN-33 HD-tES system includes built-in safeguards to prevent excessive current delivery and to ensure safe electrode contact throughout the stimulation. Participants serve as their own controls in a within-subject crossover design, increasing statistical power for detecting within-subject differences between active and sham conditions.

• Study Type: Interventional
• Enrollment (Actual): 44
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Massachusetts
    • Charlestown, Massachusetts, United States, 02129
      • Massachusetts General Hospital Research Institute

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Age 25 to 55 years
• Master's or Doctorate degree, or equivalent relevant experience
• No history of head injury or neurological or psychiatric disorders
• No history of cardiac disease
• No metal implants in the head
• No implanted electronic devices
• Not taking medication affecting neural or cardiovascular function
• Able to provide written, dated informed consent

Exclusion Criteria:

• Smoking within the past year
• Current illegal drug use
• Alcohol abuse
• Pregnancy (confirmed by urine test)
• Participation in another brain stimulation protocol within the past month

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: DLPFC Stimulation Group; Participants receive transcranial electrical stimulation (tES) targeting the left dorsolateral prefrontal cortex (DLPFC) and perform a complex cognitive-motor task using the Robotic On-Board Trainer for Research (ROBoT-r) under both active and sham stimulation in a randomized, crossover design.	Device: Active Transcranial Electrical Stimulation; Active tES delivered using the Soterix Medical MXN-33 HD-tES stimulator. Stimulation is applied via high definition electrodes targeting either the left DLPFC or L-aINS at intensities up to 1.9 mA. Stimulation is performed for up to 45 minutes during task execution. Participants perform the ROBoT-r task during stimulation.; Device: Sham Transcranial Electrical Stimulation; Sham tES using the same Soterix Medical MXN-33 HD-tES stimulator and electrode placements. Stimulation ramps up and down over 20 seconds to mimic sensation but provides no continuous current. Participants perform the ROBoT-R task under sham conditions.
Experimental: Anterior Insula Stimulation Group; Participants receive transcranial electrical stimulation (tES) targeting the left anterior insula and perform a complex cognitive-motor task using the Robotic On-Board Trainer for Research (ROBoT-r) under both active and sham stimulation in a randomized, crossover design.	Device: Active Transcranial Electrical Stimulation; Active tES delivered using the Soterix Medical MXN-33 HD-tES stimulator. Stimulation is applied via high definition electrodes targeting either the left DLPFC or L-aINS at intensities up to 1.9 mA. Stimulation is performed for up to 45 minutes during task execution. Participants perform the ROBoT-r task during stimulation.; Device: Sham Transcranial Electrical Stimulation; Sham tES using the same Soterix Medical MXN-33 HD-tES stimulator and electrode placements. Stimulation ramps up and down over 20 seconds to mimic sensation but provides no continuous current. Participants perform the ROBoT-R task under sham conditions.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
ROBoT-r Task Performance Score (During Stimulation)	Performance on the ROBoT-r computerized track-and-capture task assessed using a weighted performance score that integrates accuracy, speed, and task success metrics. Scores are scaled from 0 to 100, with higher scores indicating better performance. Participants used dual-hand controllers to grapple a simulated spacecraft in a time-limited, physics-based environment. Performance was assessed during task execution concurrent with stimulation.	5 minutes after stimulation onset
ROBoT-r Task Performance Score (Post-Stimulation)	Performance on the ROBoT-r task 15 minutes after completion of tES. Performance is quantified using a weighted composite score. Scores range from 0 to 100, with higher scores indicating better overall task performance.	15 minutes post stimulation
ROBoT-r Task Performance Score (Post-Stimulation Follow-up)	Performance on ROBoT-r task at 24 and 48 hours after completion of tES. Performance is quantified using a weighted composite score. Scores range from 0 to 100, with higher scores indicating better overall task performance.	24 and 48 hours post-stimulation

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
tES Adverse Effects Questionnaire	Self-reported adverse effects were recorded immediately following the 45-minute stimulation. Participants reported common stimulation-related sensations (e.g., tingling, scalp pain, itching, burning, headache). Effects were recorded for both active and sham stimulation conditions.	Immediately following each stimulation session (active and sham), up to approximately 45 minutes per session.
fNIRS Data Availability	Functional near-infrared spectroscopy (fNIRS) data were collected during task performance. This outcome reports the number of participants with usable fNIRS data available within each stimulation location group. Hemodynamic activation analyses are not reported here and may be provided in a future update.	Throughout study sessions when fNIRS was collected (during stimulation and post-stimulation follow-ups).

Collaborators and Investigators

• Sponsor: Massachusetts General Hospital
• Investigators: Principal Investigator: Gary Strangman, PhD, Massachusetts General Hospital

Study record dates

Study Major Dates

• Study Start (Actual): December 1, 2022
• Primary Completion (Actual): October 31, 2024
• Study Completion (Actual): October 31, 2024

Study Registration Dates

• First Submitted: May 13, 2025
• First Submitted That Met QC Criteria: May 21, 2025
• First Posted (Actual): May 29, 2025

Study Record Updates

• Last Update Posted (Actual): May 15, 2026
• Last Update Submitted That Met QC Criteria: May 8, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Neuromodulation; Attention; Non-Invasive Brain Stimulation; Neurocognitive Function; Working Memory; Cognitive Enhancement; Dorsolateral Prefrontal Cortex; Double-Blind Study; Transcranial Electrical Stimulation; Task Performance; Human Performance; Anterior Insula; Sham-Controlled Study; Learning and Memory; Operational Performance; Brain-Behavior Relationships; Neuronal Excitability; Functional Near-Infrared Spectroscopy (fNIRS)
• Other Study ID Numbers: 2020P002253; NNX16AO30G (Other Grant/Funding Number: National Aeronautics and Space Administration (NASA))

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: All IPD from this project will be anonymized IPD and shared. Data will be coded with a key only available to the Principal Investigator.
• IPD Sharing Time Frame: Data will be made available by the end-date of the funded project (estimated 12/25/2025) and retained indefinitely.
• IPD Sharing Access Criteria: Researchers will be allowed to request the data form the NASA NLSP through their website https://nlsp.nasa.gov/explore/page/home. NASA will be responsible for vetting requests and providing the data as requested.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ANALYTIC_CODE

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No