HD-tDCS Over the dACC in High Trait Impulsivity
Condition: Impulsive Behavior
MeSH terms: Impulsive Behavior
Study type: Interventional

Summary: 
      Psychological disorders characterized by impulsivity often show alterations in dorsal
      anterior cingulate cortex (dACC) activity. Recent research has therefore focused on
      non-invasive neurostimulation therapies for the modulation of functional activity in the
      dACC. To date there has only been one proof-of-concept study providing evidence for
      modulating dACC activity with non-invasive electrical neurostimulation (e.g. transcranial
      electrical stimulation). Since transcranial Direct Current Stimulation (tDCS) is relatively
      safe, tolerable, and mobile as compared to other neurostimulation techniques, it is
      worthwhile looking further into the effects of tDCS on functional dACC activity. The aim of
      the present research is to explore whether HD-tDCS can induce changes in the dACC in
      individuals with high trait impulsivity (N=20) in a double-blind cross-over study. Functional
      changes in dACC activity will be measured by the error related negativity (ERN), which is an
      event related potential generated by the dACC. The ERN is less pronounced in people that
      score high on impulsivity. It is therefore expect enhanced ERN amplitudes after HD-tDCS over
      the dACC. In addition, performance on the multisource interference task will be used as
      measure of dACC activity. It is hypothesize that increased dACC activity will be related to
      decreased impulsivity in high impulsive individuals as shown by improved inhibitory control
      on the Go/NoGo task. The results of the study may have implications for patient populations
      that are characterized by impulsivity.
    


Intervention name(s): Active High Definition transcranial Direct Current Stimulation (HD-tDCS); Sham High Definition transcranial Direct Current Stimulation (HD-tDCS)
Intervention type(s): Device; Device
Intervention description(s): TDCS is a non-invasive neuromodulation technique that modulates membrane potentials by means of small electrical currents. Electrical currents induced by tDCS electrodes produce an electrical field that modulates the excitability of brain areas. In the present HD-tDCS montage, one anodal electrode and four return electrodes are applied. Hereby, the anodal electrode modulates the excitability of the targeted area, whereas the other 4 electrodes return electrical currents that flow away from that area. Direct currents will be transmitted through 5 circular PiStim electrodes of 3.14cm2 (Neuroelectrics, Barcelona, Spain; current density=0.32 mA/cm2) with a current intensity of 1.5 mA. The HD-tDCS session will last for 20 minutes in total, with a 60 sec ramp at the beginning and end of the session. The electrodes will be filled with conductive gel and plugged into an EEG cap, with the anode placed over Fz and the four return electrodes over Fp1, Fp2, F7, and F8 (10-20 system).; For the sham-condition, the placement of the electrodes was identical to active HD-tDCS stimulation with the anode placed over Fz and the four return electrodes over Fp1, Fp2, F7, and F8 (10-20 system). The direct current, also transmitted through 5 circular PiStim electrodes of 3.14cm2 (Neuroelectrics, Barcelona, Spain; current density=0.32 mA/cm2), was increased in a ramp-like fashion over 60 seconds until it reached 1.5 mA. Directly after ramp-up, the current intensity was gradually switched off over 60 seconds, followed by 20 minutes without active stimulation. Sham procedures for tDCS mimic the transient skin sensation at the beginning of active HD-tDCS, without producing any conditioning effects on the brain. Consequently, participants are reliably blinded for sham tDCS.
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Device Feasibility
Keywords: Impulsivity; HD-tDCS; dACC; ERN; Go/NoGo; MSIT