Exploring the neural correlates of charitable giving - a Non-Invasive Brain Stimulation Study

nderstanding the neural, metabolic, and psychological mechanisms underlying human altruism and decision-making is a complex and important topic 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 be used to 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 2mA for 20 minutes (active group) and 1 minute (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 guilt in both active and sham groups tended to decrease. The results indicate that self-reported happiness can be modulated, possibly due to changes in GABA and Glx concentrations following repeated stimulation. Therefore, local changes may induce remote changes in the reward network through interactions with other metabolites, previously thought unreachable with noninvasive stimulation techniques