Recruiting

M1 tDCS

Sponsor:

Trustees of Dartmouth College

Code:

NCT06989749

Conditions

We Are Not Studying a Disease or Condition

Eligibility Criteria

Sex: All

Age: 18 - 55

Healthy Volunteers: Accepted

Interventions

Anodal tDCS

Cathodal tDCS

Sham tDCS

Study Details

Brief summary:

This double-blind randomized crossover study aims to examine the effects of left primary motor cortex (M1) tDCS on evoked thermal pain perception, pain-related decision making, and placebo effects by manipulated pain and monetary offers accepted by others. The investigators plan to collect data for up to 50 participants who undergo four separate sessions: an initial pain calibration session and three experimental sessions with either anodal, cathodal, or sham tDCS. Each session includes pain testing before and after a single tDCS protocol (either anodal, cathodal, or sham), a pain-monetary decision-making task, and social placebo pain tests. All tasks following tDCS will take place inside the MR scanner. The investigators hypothesize that anodal M1 tDCS will decrease pain ratings, and that cathodal tDCS will increase them, both relative to the sham condition. The investigators will also examine the effects of M1 tDCS on social decision-making to examine whether it affects participants' valuation of pain and their altruistic behavior, as well as how these same factors impact pain sensation in the placebo task. The investigators hypothesize that participants will behave hyperaltruistically during the decision-making task, and that the same factors that influence choice will also impact pain perception in the same context.

Conditions

We Are Not Studying a Disease or Condition

Study ID

NCT06989749

Start date

Sep 9, 2023

Status verified date

Oct, 2026

Completion date

Nov 30, 2026

Anticipated

Primary completion date

Nov 30, 2026

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 55

Healthy Volunteers: Accepted

Inclusion Criteria:

  • ages 18-55
  • Participants must be capable of performing experimental tasks (e.g., are able to read)
  • Fluent or native speakers of English

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)
  • No history of stroke or other major neurological diagnosis.
  • No self-reported current chronic pain, or acute pain within three months of the study period.
  • No current migraine disorder (i.e., 15 headache days or more in 1 month).
  • No use of central nervous system-effective medication or other medication for neurological/psychiatric treatment. No self-reported substance abuse within the last six months.
  • No contraindication to MRI or tDCS (e.g., pregnancy, claustrophobia, pacemakers, ear/cochlear implants, shrapnel injuries, clips, or other ferromagnetic/electrical objects/devices, diagnosed brain abnormality such as tumor, or skin lesions on the scalp.).
  • No contraindications for induced pain (e.g., no heart disease, high blood pressure, heart surgery, heart problems of any kind, severe asthma, respiratory problems of any kind, fibromyalgia, Raynaud's Syndrome or Disease, chronic pain, diabetes).

Study Design

Enrollment

50 participants

Anticipated

Allocation

Randomized

Intervention Model

Crossover

Primary purpose

Basic Science

Interventions and Outcome Measures

Arms

other: Condition 1: Anodal tDCS -> Cathodal tDCS -> Sham tDCS

Each participant experiences an initial pain calibration session, followed by three full study sessions involving anodal, cathodal, or sham tDCS interventions. Only one intervention type (anodal, cathodal, or sham) is applied per session, in a randomized and double-blind fashion. In this arm anodal is applied session 1, cathodal is applied session 2, and sham is applied session 3.

other: Condition 2: Anodal tDCS -> Sham tDCS -> Cathodal tDCS

Each participant experiences an initial pain calibration session, followed by three full study sessions involving anodal, cathodal, or sham tDCS interventions. Only one intervention type (anodal, cathodal, or sham) is applied per session, in a randomized and double-blind fashion. In this arm anodal is applied session 1, sham is applied session 2, and cathodal is applied session 3.

other: Condition 3: Sham tDCS -> Cathodal tDCS -> Anodal tDCS

Each participant experiences an initial pain calibration session, followed by three full study sessions involving anodal, cathodal, or sham tDCS interventions. Only one intervention type (anodal, cathodal, or sham) is applied per session, in a randomized and double-blind fashion. In this arm sham is applied session 1, cathodal is applied session 2, and anodal is applied session 3.

other: Condition 4: Sham tDCS -> Anodal tDCS -> Cathodal tDCS

Each participant experiences an initial pain calibration session, followed by three full study sessions involving anodal, cathodal, or sham tDCS interventions. Only one intervention type (anodal, cathodal, or sham) is applied per session, in a randomized and double-blind fashion. In this arm sham is applied session 1, anodal is applied session 2, and cathodal is applied session 3.

other: Condition 5: Cathodal tDCS -> Sham tDCS -> Anodal tDCS

Each participant experiences an initial pain calibration session, followed by three full study sessions involving anodal, cathodal, or sham tDCS interventions. Only one intervention type (anodal, cathodal, or sham) is applied per session, in a randomized and double-blind fashion. In this arm cathodal is applied session 1, sham is applied session 2, and anodal is applied session 3.

other: Condition 6: Cathodal tDCS -> Anodal tDCS -> Sham tDCS

Each participant experiences an initial pain calibration session, followed by three full study sessions involving anodal, cathodal, or sham tDCS interventions. Only one intervention type (anodal, cathodal, or sham) is applied per session, in a randomized and double-blind fashion. In this arm cathodal is applied session 1, anodal is applied session 2, and sham is applied session 3.

Interventions

Anodal tDCS

Transcranial direct current stimulation (tDCS) is an experimental manipulation of brain circuitry using electrical current applied to the scalp. The equipment is commercially available (StarStim8, Neuroelectrics, Spain) and marketed for experimental research on brain function. Current is applied at 2 mA for 20 minutes. Electrodes are placed on the C3 and FP2 regions. There is a 30-second ramp-up and 30-second ramp-down of stimulation for each tDCS condition to minimize any discomfort during stimulation. In the anodal condition, real tDCS stimulation enters from the C3 electrode, and exits at the FP2 electrode.

Cathodal tDCS

Transcranial direct current stimulation (tDCS) is an experimental manipulation of brain circuitry using electrical current applied to the scalp. The equipment is commercially available (StarStim8, Neuroelectrics, Spain) and marketed for experimental research on brain function. Current is applied at 2 mA for 20 minutes. Electrodes are placed on the C3 and FP2 regions. There is a 30-second ramp-up and 30-second ramp-down of stimulation for each tDCS condition to minimize any discomfort during stimulation. In the cathodal condition, real tDCS stimulation enters from the FP2 electrode, and exits at the C3 electrode.

Sham tDCS

This is the sham (or placebo) tDCS intervention. The tDCS device is applied for one minute, for a 30-second ramp-up and 30-second ramp-down of stimulation.

Primary outcome measure

  • Pain Visual Analogue Scale [ Time Frame: 3-10 sec post-stimulus throughout testing sessions, on average complete within 1 month ]

Central Contacts and Locations

Central contacts

Tor Wager D Principal Investigator, PhD

603-646-2196Tor.D.Wager@Dartmouth.edu

Locations

Dartmouth College

Recruiting

Hanover, New Hampshire, United States, 03755

Contacts

David Gantz M Lab Manager, MA

423-557-3790david.m.gantz@dartmouth.edu

More Information

Sponsor

Trustees of Dartmouth College

Last update posted

Oct 7, 2026

Last verified

Oct, 2026

Keywords

  • transcranial direct current stimulation
  • experimental pain
  • pain-related decision-making
  • social placebo effects

Trial information was received from ClinicalTrials.gov and was last updated on 2026-10-08. This information was provided to ClinicalTrials.gov by Trustees of Dartmouth College on 2026-10-07. Recruitment status is synced daily from ClinicalTrials.gov and may not reflect the sponsor's current status. Confirm during your call.