Effect of tACS Stimulation on Alpha Oscillations

Study Overview
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Brief Summary
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Transcranial Alternating Current Stimulation (tACS) is one method that has been demonstrated to enhance alpha oscillations in healthy participants by applying weak electrical currents to the scalp to modulate rhythmic brain activity patterns. This study will involve tACS-induced frontal alpha oscillations, EEG recordings, and other physiological and biological measures.

Official Title
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Rational Optimization of tACS for Targeting Thalamo-Cortical Oscillations (Experiment 2)

Conditions
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Healthy

Intervention / Treatment
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* Device: XCSITE100 Stimulator tACS
* Device: XCSITE100 Stimulator Sham


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Ages 18-65 Capacity to understand all relevant risks and potential benefits of the study (informed consent) Negative pregnancy test for female participants Exclusion Criteria: History of major neurological or psychiatric illness, including epilepsy Medication use associated with neurological or psychiatric illnesses Currently undergoing counseling or psychotherapy treatment for depression, anxiety, eating disorders, PTSD or other behavioral conditions First degree relative (parent, sibling, child) with major neurological or psychiatric illness Prior brain surgery Major head injury Any brain devices/implants (including cochlear implants and aneurysm clips) Braids or other hair styling that prevents direct access to the scalp (if removal not possible) Skin allergies or very sensitive skin Pregnant or nursing females Failure to pass a urinary drug test at the first session Use of hormonal birth control or supplements in the past two weeks Non English speakers Cardiovascular disease

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Each participant will receive sham stimulation or 10 Hz tACS stimulation at two separate sessions. The order will be randomized (ie, half the participants will receive sham stimulation at the first session and 10 Hz tACS stimulation at the second session, and the other half will receive 10 Hz tACS stimulation at the first session and sham stimulation at the second session).
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Sham Stimulation, then Alpha Stimulation<br>Participants receive sham stimulation at the first session, followed by a 5-9 day washout period and alpha stimulation at the second session. Sham Stimulation mimics the physical effects of stimulation, with up to one minute of stimulation during the session. Sham stimulation is delivered using the XCSITE100 Stimulator Sham. Participants will receive 2 mA of alternating current stimulation at a frequency of 10 Hz for 40 minutes. tACS stimulation is delivered using the XCSITE100 Stimulator tACS. | Device: XCSITE100 Stimulator tACS<br>* Transcranial alternating current stimulation (tACS) is a method of noninvasive brain stimulation in which weak electrical current are applied to the scalp in a sine wave pattern to induce cortical oscillations at the frequency at which they are applied.<br>* Other names: tACS;Device: XCSITE100 Stimulator Sham<br>* The participant will receive up to one minute of tACS stimulation until the stimulation fades. Sham stimulation mimics the skin sensations a participant would experience during a tACS session.<br>* Other names: Sham tACS;|
| Experimental: Alpha Stimulation, then Sham Stimulation<br>Participants receive alpha stimulation at the first session, followed by a 5-9 day washout period and sham stimulation at the second session. Participants will receive 2 mA of alternating current stimulation at a frequency of 10 Hz for 40 minutes. tACS stimulation is delivered using the XCSITE100 Stimulator tACS. Sham Stimulation mimics the physical effects of stimulation, with up to one minute of stimulation during the session. Sham stimulation is delivered using the XCSITE100 Stimulator Sham. | Device: XCSITE100 Stimulator tACS<br>* Transcranial alternating current stimulation (tACS) is a method of noninvasive brain stimulation in which weak electrical current are applied to the scalp in a sine wave pattern to induce cortical oscillations at the frequency at which they are applied.<br>* Other names: tACS;Device: XCSITE100 Stimulator Sham<br>* The participant will receive up to one minute of tACS stimulation until the stimulation fades. Sham stimulation mimics the skin sensations a participant would experience during a tACS session.<br>* Other names: Sham tACS;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Salivary Alpha Amylase | Change after stimulation | Before and after 40-minute stimulation at each session. | 
| Salivary Cortisol | Change before and after stimulation | Before and after 40 minutes of stimulation | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Heart Rate Variability | Change in the ratio between the power in low frequency band and the power in high frequency band. As this outcome variable is a ratio between two items that are measured in microvolt^2, the ratio does not have a unit of measure. | Before and after 40-minute stimulation at each session. | 
| Percent Change in Respiration | Respiration rate, measured via a belt placed around the participant's abdomen as breaths per second. | Before and after 40-minute stimulation at each session. | 
| Electroencephalogram (EEG) | The investigators will compare alpha oscillation power from resting-state EEG recordings before and after stimulation/sham at each session. | Before and after 40-minute stimulation at each session. |