no participants enrolled

TACS is an emergent method of non-invasive neuromodulation which can engage frequency-specific brain oscillations. It is increasingly recognized that neural oscillations play a system-organizing role in the brain. Evidence suggests that disorganized neural oscillations may also influence functionality of cognitive processes such as working memory. Thus, as TACS can affect neural oscillatory activity in the human brain in a non-invasive manner, it has promise to transform mental health care. The premise of this proposed work is that tACS concurrent with multi-session working memory (WM) focused skills will facilitate durable working memory and stabilized neural oscillations. Depression offers an excellent model to study the effects of tACS. The study seeka to administer 2mA of tACS using theta oscillations to improve working memory concerns associated with depression. The purpose of this study is to investigate the electrophysiological and behavioral effects of transcranial alternating current stimulation (tACS) in humans and to explore specific improvements in working memory and depressive symptoms. This study is placebo-controlled study. Participants will undergo pre- and post-assessments and either theta or sham tACS for 5 days. During each session, the volunteer will perform cognitive tasks while receiving tACS. Assessment sessions will include cognitive tasks, questionnaires, a clinical interview, and EEG.

Inclusion Criteria:

• Age between 18 and 60 years old.
• Stated willingness to participate and comply with all study procedures.
• Stated availability for the duration of the study.
• Meet criteria for Major Depressive Disorder.
• Agreement to adhere to lifestyle considerations throughout study duration.
• No conflict of interest with the Department of Biomedical Engineering at the University of Minnesota.
• Confident level of English language.

Exclusion Criteria:

• History or evidence of chronic neurological disorder (e.g., history of seizures, epilepsy, unexplained episodes of loss of consciousness, serious brain injury, severe or frequent headaches)
• Metal or electric implant in the head, neck or chest area.
• Implanted pacemakers or other electrically, magnetically, ir mechanically activated implant
• Vascular clips or other electrically sensitive support systems in the brain
• Serious health conditions (e.g., congestive heart failure pulmonary obstructive chronic disease, active neoplasia)
• History of head injuries.
• Pregnancy or breast-feeding.
• Significant damage of skin at sites of stimulation or other skin concerns, such as dermatitis, psoriasis, or eczema
• Alcohol or drug addiction.
• Any legal reason why the candidate cannot participate.
• Concurrent enrollment in another scientific or clinical study.
• Estimated IQ is below 70, defined by the WTAR.
• Active suicidality or other non-controlled neuropsychiatric illness. Active suicidality will be excluded based on a C-SSRS score of 3 or above in the last 6 months. Severe depression is defined as a PHQ-9 score above 20, which will also be excluded.
• A lifetime suicide attempt.