What is it about?
Why are we generous to some people but not to others? Which brain mechanisms govern our decision to be generous toward others? And how is the internal conflict between maximizing our own benefit and considering the well-being of others resolved in the brain? Our latest research sheds new light on this question by uncovering the role of the basolateral amygdala (BLA) in social decision-making. Together with Jack van Honk, Luca Lüpken, David Terburg and Ron Stoop, we had the rare opportunity to study individuals with Urbach-Wiethe syndrome in South Africa—a genetic condition that selectively damages the BLA while leaving other brain areas intact. This gave us a unique "natural experiment" to explore how the BLA contributes to prosocial behavior. In a so-called social discounting task, participants decided how much money to share with emotionally close or distant others. We found that most individuals with BLA damage were as generous as healthy, matched control participants when interacting with loved ones—but significantly less generous toward acquaintances or strangers. Key takeaway: The BLA does not determine whether we are generous—it helps us fine-tune our generosity depending on how emotionally close or distant we feel to someone.
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Photo by Katt Yukawa on Unsplash
Why is it important?
Our findings help reconcile conflicting results from previous studies. Our results are consistent with theoretical ideas stressing the BLA’s importance in balancing self- and other-regarding motives, underlining its crucial role in model-based social cognition.
Perspectives
I collected the data for this study during my sabbatical, and it was an exceptionally rewarding experience. The Namaqualand region of South Africa is a fascinating and unique research setting, and being there was a privilege in itself. But the true highlight was the interaction with our participants—both individuals with Urbach-Wiethe disease and control participants. Without exception, they were extraordinarily kind, welcoming, and engaging. Our findings that damage to the BLA reduced generosity should not be taken to imply that the Urbach-Wiethe participants are selfish or self-centered. The exact opposite is the case, I came to know them as warmhearted, friendly, and thoroughly pleasant individuals. Our study reveals just one facet of their social behavior that emerges only under particular experimental conditions. In everyday interactions, their warmth and generosity were striking. Another deeply enjoyable aspect of this project was the collaboration with my co-authors. From the beginning to the end, working together was a pleasure, and I am grateful for the shared journey.
Tobias Kalenscher
Heinrich-Heine University Düsseldorf
Read the Original
This page is a summary of: Steeper social discounting after human basolateral amygdala damage, Proceedings of the National Academy of Sciences, April 2025, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2500692122.
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