The study investigated the effect of neurofeedback on the ventral tegmental area (VTA) in relation to the immune response to hepatitis B vaccination. Up-regulation of VTA activity through neurofeedback led to a stronger immune response. VTA upregulation was achieved by conscious positive expectations. This is a randomized controlled trial published in Nature Medicine on January 19, 2026. Positive expectations activate the mesolimbic reward pathway, which affects the immune system. The main finding confirms the link between activity of the reward system and better response to the vaccine.[4]