Neural Mechanisms of Interpersonal Expectations on Negative Affect
Trustees of Dartmouth College
Summary
The goal of this clinical trial is to learn whether non-invasive brain stimulation, called transcranial temporal interference stimulation (tTIS), can reduce negative affect, and how expectations shaped by care providers influence these effects. The main questions this study aims to answer are: (1)Does active tTIS reduce negative affect more effectively than sham (inactive) tTIS? (2)Do positive treatment expectations enhance the effects compared to negative expectations? Participants will: (1) Receive either active or sham tTIS. (2) Be provided with positive or negative messaging regarding treatment effectiveness. (3) Interact with care providers and complete assessments measuring negative affect and physiological responses.
Description
The study employs a within-subject, crossover factorial design, consisting of two experiments. Experiment 1 In Experiment 1, 30 participants ('patients') will complete all combinations of two independent variables-stimulation type (active vs. sham tTIS) and placebo manipulation (positive vs. negative placebo messaging)-resulting in four sessions: * Session A: Positive Placebo + Active tTIS * Session B: Positive Placebo + Sham tTIS * Session C: Negative Placebo + Active tTIS * Session D: Negative Placebo + Sham tTIS Participants complete three multimodal negative affect tasks (MNAT) before…
Eligibility
- Age range
- 18–55 years
- Sex
- All
- Healthy volunteers
- Yes
Inclusion Criteria: 'Doctors' are recruited from medical students at the Geisel School of Medicine and resident physicians at Dartmouth Hitchcock Medical Center (DHMC). Exclusion Criteria: * No self-reported current or history of depression, bipolar disorder, or other psychiatric diagnosis * No self-reported current seizure disorder (i.e., seizure within past 10 years), or history of stroke or other major neurological diagnosis that can cause cognitive impairment * No self-reported current chronic pain, or acute pain within three months of the study period * No current migraine disorder (i.…
Interventions
- BehavioralSession A: Positive Placebo + Active tTIS
Participants receive active tTIS, with two signals set at 2000 Hz and 2080 Hz, creating an 80 Hz interference beat targeting the anterior/mid-cingulate cortex (aMCC). Stimulation is delivered at 2 mA for 20 minutes. The stimulation is combined with a positive social placebo intervention delivered by the care provider. Participants complete three multimodal negative affect tasks (MNAT) before and after the stimulation.
- BehavioralSession B: Positive Placebo + Sham tTIS
Participants receive sham tTIS, using two identical 2000 Hz signals that produce no low-frequency interference. The device mimics active parameters (2 mA, 20 minutes) without delivering effective stimulation. The sham stimulation is paired with a positive social placebo intervention. Participants complete three MNAT tasks before and after the session.
- BehavioralSession C: Negative Placebo + Active tTIS
Participants receive active tTIS (2000 Hz and 2080 Hz signals, 2 mA, 20 minutes) combined with a negative social placebo intervention (neutral or skeptical messaging about treatment efficacy). Participants complete three MNAT tasks before and after the stimulation.
- BehavioralSession D: Negative Placebo + Sham tTIS
Participants receive sham tTIS (identical 2000 Hz signals, mimicking active stimulation) combined with a negative social placebo intervention. Participants complete three MNAT tasks before and after the session.
Location
- Dartmouth College, Department of Psychological and Brain SciencesHanover, New Hampshire