Recruiting

Observational Study

Sponsor:

Massachusetts General Hospital

Code:

NCT05923606

Conditions

Working Memory

Eligibility Criteria

Sex: All

Age: 18 - 35

Healthy Volunteers: Accepted

Interventions

Active tACS

Placebo tACS

Study Details

Brief summary:

This study will use novel transcranial alternating current stimulation (tACS) protocols and electroencephalography (EEG) to modulate and measure brain oscillations that underlie working memory. tACS is a noninvasive method used to modulate the timing and patterns of brain rhythms via weak electric currents passed through electrodes on the scalp.

Conditions

Working Memory

Study ID

NCT05923606

Start date

Jul 10, 2024

Status verified date

Feb, 2026

Completion date

Mar 31, 2027

Anticipated

Primary completion date

Aug 31, 2026

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 35

Healthy Volunteers: Accepted

Inclusion Criteria:

  • Able to provide informed consent
  • Fluent in English.

Exclusion Criteria:

  • History of a neurological/psychiatric disorder
  • Current use of psychotropic medications
  • Current use of substances and drugs that were shown to affect tES (transcranial electrical stimulation) efficacy (dopamine altering drugs, nicotine, NMDA (N-methyl-D-aspartate) antagonists/agonists, sodium/calcium channel blockers, norepinephrine reuptake inhibitors, GABAergic modulators and selective serotonin reuptake inhibitors)
  • Contraindications for tACS (e.g., history of seizures, metallic implants in the head or neck, implanted brain stimulators, vagus nerve stimulators, pacemakers, pregnancy)

Study Design

Enrollment

32 participants

Anticipated

Allocation

Randomized

Intervention Model

Crossover

Primary purpose

Basic Science

Interventions and Outcome Measures

Arms

experimental: Theta-nested gamma tACS applied during passive task epochs

Participants will receive single-session administration of tACS during performance of a working memory task. tACS will be applied during fixation periods between consecutive task trials. EEG will be acquired before and immediately after the intervention.

experimental: Theta-nested gamma tACS applied during memory delays

Participants will receive single-session administration of tACS during performance of a working memory task. tACS will be applied during memory delays. EEG will be acquired before and immediately after the intervention.

experimental: Gamma tACS applied during memory delays

Participants will receive single-session administration of tACS during performance of a working memory task. tACS will be applied during memory delays. The stimulation will be phase locked to the peaks of ongoing theta rhythms of the participant. EEG will be acquired before and immediately after the intervention.

placebo comparator: Placebo tACS applied during task performance

Participants will receive single-session administration of placebo tACS during performance of a working memory task. EEG will be acquired before and immediately after the intervention.

Interventions

Active tACS

Active tACS will be administered over the left dorsolateral prefrontal cortex for approximately 25 minutes.

Placebo tACS

Placebo tACS will be administered over the left dorsolateral prefrontal cortex for approximately 25 minutes.

Primary outcome measure

  • Working memory accuracy [ Time Frame: 2 hours ]
  • Working memory accuracy under interference [ Time Frame: 2 hours ]
  • Theta-gamma cross-frequency coupling [ Time Frame: 2 hours ]
  • Fronto-parietal theta phase synchronization [ Time Frame: 2 hours ]

Central Contacts and Locations

Central contacts

Allyson Smith, B.S.

(617) 726-1040asmith192@mgh.harvard.edu

Hamdi Eryilmaz, Ph.D.

(617) 643-7462hamdi.eryilmaz@mgh.harvard.edu

Locations

Martinos Center for Biomedical Imaging

Recruiting

Charlestown, Massachusetts, United States, 02129

More Information

Sponsor

Massachusetts General Hospital

Last update posted

Feb 9, 2026

Last verified

Feb, 2026

Keywords

  • Working memory
  • Attention
  • Theta oscillations
  • Transcranial Alternating Current Stimulation

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by Massachusetts General Hospital on 2026-02-09.