Neural Mechanisms of Interpersonal Expectations on Negative Affect

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.

Conditions

• Negative Affectivity
• Non-invasive Brain Stimulation
• Placebo Effect
• Expectations

Interventions

BEHAVIORAL

Session 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.

BEHAVIORAL

Session 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.

BEHAVIORAL

Session 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.

BEHAVIORAL

Session 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.

BEHAVIORAL

Session E: On-Placebo + Sham tTIS

Participants receive sham tTIS (brief 15-second stimulation followed by no current) paired with a positive social placebo intervention. Participants complete three MNAT tasks before and after the session.

BEHAVIORAL

Session F: Off-Placebo + Sham tTIS

Participants receive sham tTIS (brief 15-second stimulation, then no current) without any placebo intervention. Participants complete three MNAT tasks before and after the session.

Sponsors & Collaborators

• Trustees of Dartmouth College

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

TRIPLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

55 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2025-09-01

Primary Completion

2027-08-31

Completion

2028-03-03

Countries

• United States

Study Locations