ABSTRACT
Understanding the neural, metabolic, and psychological mechanisms underlying human altruism and decision-making is a complex and important topic both for science and society. Here, we investigated whether transcranial Direct Current Stimulation (tDCS) applied to two prefrontal cortex regions, the ventromedial prefrontal cortex (vmPFC, anode) and the right dorsolateral prefrontal cortex (DLPFC, cathode) can induce changes in self-reported emotions and to modulate local metabolite concentrations. We employed in vivo quantitative MR Spectroscopy in healthy adult participants and quantified changes in GABA and Glx (glutamate + glutamine) before and after five sessions of tDCS delivered at 2 mA for 20 min (active group) and 1 min (sham group) while participants were engaged in a charitable donation task. In the active group, we observed increased levels of GABA in vmPFC. Glx levels decreased in both prefrontal regions and self-reported happiness increased significantly over time in the active group. Self-reported guiltiness in both active and sham groups tended to decrease. The results indicate that self-reported happiness can be modulated, possibly due to changes in Glx concentrations following repeated stimulation. Therefore, local changes may induce remote changes in the reward network through interactions with other metabolites, previously thought to be unreachable with noninvasive stimulation techniques.
Subject(s)
Emotions , Prefrontal Cortex , Transcranial Direct Current Stimulation , gamma-Aminobutyric Acid , Humans , Male , Female , Prefrontal Cortex/metabolism , Prefrontal Cortex/physiology , Adult , Emotions/physiology , Young Adult , gamma-Aminobutyric Acid/metabolism , Glutamic Acid/metabolism , Altruism , Glutamine/metabolism , Magnetic Resonance Spectroscopy/methods , Dorsolateral Prefrontal Cortex/metabolism , Dorsolateral Prefrontal Cortex/physiologyABSTRACT
What role does intergroup contact play in promoting support for social change toward greater social equality? Drawing on the needs-based model of reconciliation, we theorized that when inequality between groups is perceived as illegitimate, disadvantaged group members will experience a need for empowerment and advantaged group members a need for acceptance. When intergroup contact satisfies each group's needs, it should result in more mutual support for social change. Using four sets of survey data collected through the Zurich Intergroup Project in 23 countries, we tested several preregistered predictions, derived from the above reasoning, across a large variety of operationalizations. Two studies of disadvantaged groups (Ns = 689 ethnic minority members in Study 1 and 3,382 sexual/gender minorities in Study 2) support the hypothesis that, after accounting for the effects of intergroup contact and perceived illegitimacy, satisfying the need for empowerment (but not acceptance) during contact is positively related to support for social change. Two studies with advantaged groups (Ns = 2,937 ethnic majority members in Study 3 and 4,203 cis-heterosexual individuals in Study 4) showed that, after accounting for illegitimacy and intergroup contact, satisfying the need for acceptance (but also empowerment) is positively related to support for social change. Overall, findings suggest that intergroup contact is compatible with efforts to promote social change when group-specific needs are met. Thus, to encourage support for social change among both disadvantaged and advantaged group members, it is essential that, besides promoting mutual acceptance, intergroup contact interventions also give voice to and empower members of disadvantaged groups. (PsycInfo Database Record (c) 2022 APA, all rights reserved).
