Prosocial decision-making after human basolateral amygdala damage

• Applicant: Professor Dr. Tobias Kalenscher
• Subject Area: Biological Psychology and Cognitive Neuroscience ; Cognitive, Systems and Behavioural Neurobiology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 563814557

In this grant proposal, we aim to investigate the role of the basolateral amygdala (BLA) in prosocial behavior in patients with Urbach-Wiethe Disease (UWD). UWD is a very rare genetic condition that causes selective lesions in BLA while leaving other brain areas intact. Animal studies show that BLA computes some of the core functional processes involved in other-regarding behavior, and, they consequently suggest that BLA is crucial for prosociality. By contrast, research on UWD patients yields conflicting results: compared to healthy controls, UWD patients exhibit hyperaltruism in the trust game, hypermoral decision-making in moral dilemmas, and they are more willing to exert physical effort for the benefit of other people. Hence, the story is more complicated than the simple equation that BLA integrity is necessary for prosociality. In this grant proposal, we aim to elucidate the role of human BLA in prosocial decision-making. We hypothesize, based on theory and preliminary data, that social distance matters for BLA lesions, i.e., how much or little a participant emotionally cares about the recipient of help in a resource allocation problem. We further argue that the type of costs, i.e., physical effort costs vs. monetary costs, in a prosocial choice task makes a difference for the patients’ level of prosociality. And, finally, we predict that BLA lesions reduce the flexibility in integrating social norms into other-regarding preferences, making UWD patients less susceptible to framing effects in prosocial choice (here, framing effects describe the phenomenon that the way a decision problem is worded influences the participants’ degree of prosociality). To test these predictions, we aim to 1. develop an effort-based social discounting task to investigate how much effort participants are willing to exert for the benefits of others that vary in social distance to them; 2. compare UWD patients and healthy controls on this new task, as well as on standard monetary-based social discounting tasks; 3. investigate whether UWD patients exhibit reduced framing effects during social discounting. Our results will inform theories proposing that BLA is important for weighing self-interest against other-regarding motives during prosocial choice. They have further implications for a broader understanding of BLA function in cognition and behavior, linking BLA to model-based reinforcement learning. Finally, an important, highly relevant by-product of our proposal beyond amygdala research is to validate all tasks in a diverse non-WEIRD (not Western, Educated, Industrialized, Rich, and Democratic) population in South Africa.

• DFG Programme: Research Grants
• International Connection: South Africa
• Cooperation Partner: Professor Dr. Jack van Honk