Modulation of Brain Oscillations Underlying Working Memory

Not Applicable

Recruiting

• Conditions: Working Memory
• Interventions: Device: Placebo tACS; Device: Active tACS

• Registration Number: NCT05923606
• Lead Sponsor: Massachusetts General Hospital

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.

Detailed Description

In this study, healthy adult individuals will perform a spatial working memory task as investigators record scalp EEG before and immediately after undergoing transcranial alternating current stimulation (tACS). Each participant will complete four tACS sessions in randomized order: 1) theta-nested gamma tACS applied during active task periods, 2) theta-nested gamma tACS applied during passive (rest) periods, 3) gamma stimulation applied in phase with ongoing theta oscillations, and 4) placebo tACS. The different stimulation protocols will take place on different days. Therefore, participants will be expected to attend 4 in-person study visits at the Martinos Center for Biomedical Imaging in Charlestown, Massachusetts.

Study Timeline

• Study First Submitted: 2023-06-20
• Study First Submitted QC: 2023-06-27
• Study First Posted: 2023-06-28
• Study Start: 2024-07-10
• Status Verified: 2024-11
• Last Update Submitted: 2024-11-18
• Last Update Posted: 2024-11-20
• Primary Completion: 2025-08-31
• Study Completion: 2026-08-31

Recruitment & Eligibility

• Status: RECRUITING
• Sex: All
• Target Recruitment: 32

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

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Placebo tACS applied during task performance	Placebo tACS	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.
Theta-nested gamma tACS applied during passive task epochs	Active tACS	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.
Gamma tACS applied during memory delays	Active tACS	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.
Theta-nested gamma tACS applied during memory delays	Active tACS	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.

Primary Outcome Measures

Name	Time	Method
Working memory accuracy	2 hours	Accuracy of working memory retrieval during a Delayed Match-to-Sample task will be assessed before and during tACS interventions
Working memory accuracy under interference	2 hours	Accuracy of working memory retrieval during interference conditions of a Delayed Match-to-Sample task will be assessed before and during tACS interventions.
Theta-gamma cross-frequency coupling	2 hours	Cross-frequency coupling between theta band phase and gamma band amplitude will be calculated using the EEG data collected while subjects perform the Delayed Match-to-Sample task before and after tACS interventions.
Fronto-parietal theta phase synchronization	2 hours	Phase synchronization in the theta band between frontal and parietal brain regions will be calculated using the EEG data collected while subjects perform the Delayed Match-to-Sample task before and after the tACS interventions.

Trial Locations

Locations (1)

Martinos Center for Biomedical Imaging; 🇺🇸 Charlestown, Massachusetts, United States