Transcranial Direct Current Stimulation and Modulation of Affect and Pain

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.

Description

Eligibility

Age range

18–55 years

Sex

All

Healthy volunteers

Yes

Interventions

• Other
  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.

• Other
  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.

• Other
  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.

Location