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.
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 Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
32
Active tACS will be administered over the left dorsolateral prefrontal cortex for approximately 25 minutes.
Placebo tACS will be administered over the left dorsolateral prefrontal cortex for approximately 25 minutes.
Martinos Center for Biomedical Imaging
Charlestown, Massachusetts, United States
RECRUITINGWorking memory accuracy
Accuracy of working memory retrieval during a Delayed Match-to-Sample task will be assessed before and during tACS interventions
Time frame: 2 hours
Working memory accuracy under interference
Accuracy of working memory retrieval during interference conditions of a Delayed Match-to-Sample task will be assessed before and during tACS interventions.
Time frame: 2 hours
Theta-gamma cross-frequency coupling
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.
Time frame: 2 hours
Fronto-parietal theta phase synchronization
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.
Time frame: 2 hours
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