NCT04681391

tDCS, Moral Decision-Making, fMRI

The Role of Implicit Attitude in the tDCS Modulation on Moral Decision-Making

• Status: Completed
• Phase: —
• Study type: Observational
• Enrollment: 42 (actual)
• Sponsor: National Yang Ming Chiao Tung University Hospital · Academic / Other
• Sex: All
• Age: 20 Years – 30 Years
• Healthy volunteers: —

Summary

Morality is the social rule about appropriateness of the behavior, containing concepts of justice, fairness, and rights. Previous studies suggested that the activation of right temporoparietal junction (rTPJ) should be involved in mental state reasoning in moral cognition. Implicit moral attitude, which reflects people's fundamental beliefs about right and wrong, could be assessed by implicit association test on moral scenarios (mIAT), as indicated by the D scores. According to our previous findings, we postulate that, during moral decision-making, the high D group would have less rTPJ involvement and the low D group would have more. Here we applied tDCS, a non-invasive neuromodulation technique, to modulate cortical excitability in rTPJ. Based on our postulation, we divided participants into high D and low D group and hypothesized that tDCS over rTPJ would modulate the behavior depending on the group. The results revealed that, in aspect of mIAT, implicit moral attitude could be modulated differently depending on the group via tDCS over rTPJ. In addition, hemodynamic response within rTPJ showed a main effect of tDCS while carrying out the helping behavior. In conclusion, these findings indicated that tDCS over rTPJ could modulate the implicit moral attitude as well as the rTPJ activity during moral action.

Conditions

• Morality

Interventions

Type	Name	Description
DEVICE	transCranial direct current stimulation	In the present study, we applied DC Brain Stimulator Plus to stimulate right temporoparietal junction (rTPJ). The target electrode was placed over the location of rTPJ; on the other hand, the return electrode was placed over the left supraorbital area. That is, during anodal tDCS, the anode was placed over CP6, and the cathode was placed over left supraorbital area; conversely, during cathodal tDCS, the cathode was placed over CP6, and the anode was placed over left supraorbital area. For the active stimulation, which are anodal and cathodal tDCS, a constant current of 1 mA was delivered through 35 cm2 electrode for 20 minutes with fade-in and fade-out of 10 seconds, producing a current density of 0.029 mA/cm2. On the other hand, same fade-in, fade-out, and current density were applied for the sham stimulation, but the duration of current-delivering only last 35 seconds. Therefore, participants could feel the skin sensation but did not have the after-effects of tDCS.

Timeline

• Start date: 2016-12-27
• Primary completion: 2019-11-30
• Completion: 2020-12-10
• First posted: 2020-12-23
• Last updated: 2020-12-23