The Neuroscience of Generosity
Synchronization of specific brain regions predicts generous behavior in monkeys.
Posted Feb 25, 2020
What do Ebenezer ("Bah humbug") Scrooge, Gordon ("Greed is good") Gekko, and Veruca ("I want it now!") Salt have in common?
In addition to being cinematic icons of selfishness, new research from Yale University suggests that if these three characters came to life and were observed in a 21st-century neuroscience lab, their brains would probably display similar neural signatures and a lack of synchrony between the amygdala and the medial prefrontal cortex.
This paper (Dal Monte et al., 2020) was published on February 24 in Nature Neuroscience. Olga Dal Monte of Yale University's department of psychology is the paper's first author. "These findings suggest that specialized coordination in the medial prefrontal–amygdala network underlies social-decision preferences," the authors write.
"We found a unique signature of neural synchrony that reflects whether a prosocial or an antisocial decision was made," senior author Steve Chang, who is an assistant professor of psychology and neuroscience at Yale, said in a news release. "We all know there are individual differences in levels of generosity. Maybe Scrooge did not have high levels of synchrony after all."
Humans and monkeys are social creatures who display varying degrees of context-specific generosity and selfishness. Based on monkey experiments, the researchers found that just before a prosocial or antisocial behavior, primates exhibit either positive or negative "other-regarding preferences" (ORP) that are accompanied by a distinct neural signature.
Although this study was conducted with primates, the researchers speculate that humans may display similar neural signatures relating to selfishness and generosity.
During this experiment, the researchers focused on neuronal interactions between the amygdala and the medial prefrontal cortex as monkeys were faced with a "to share or not to share" decision regarding their fruit juice. Each monkey in the study experienced a few different scenarios that prompted a decision of whether or not to share some fruit juice with another monkey.
Regardless of the scenario, when monkeys decided to be generous and share their juice, the basolateral amygdala and the rostral anterior cingulate gyrus region of the medial prefrontal cortex became highly synchronized.
Conversely, when a monkey was being antisocial or behaved selfishly by not sharing any fruit juice, the neural synchronicity between the amygdala and medial prefrontal cortex was markedly suppressed.
"Synchronization between the two nodes was enhanced for a positive other-regarding preference but suppressed for a negative ORP," the authors write. "These interactions occurred in beta and gamma frequency bands depending on the area contributing the spikes, exhibited a specific directionality of information flow associated with a positive ORP and could be used to decode social decisions."
Notably, by looking at real-time neuronal data, Dal Monte et al. were able to predict if a monkey was about to be generous based on higher levels of neural synchronicity and medial prefrontal–amygdala coordination.
We all know what it feels like to be generous; it feels good and tends to make us happy. (See "Small Acts of Generous Behavior Make Your Brain Happier")
The next time you feel the urge to act like Gordon Gekko, Veruca Salt, or Scrooge—try visualizing how the neural synchronicity in your brain may be out of sync and imagine what it would feel like to shift towards other-regarding preferences that are more generous.
Of course, any positive outcomes associated with visualizing the synchronicity of your brain harmonizing in more prosocial or generous ways could be attributed to the placebo effect. That said, sometime in the near future, we may have neurofeedback technology that could help us learn how to consciously coordinate specific brain regions by dialing in synchronized neural activity.
Olga Dal Monte, Cheng C. J. Chu, Nicholas A. Fagan, and Steve W. C. Chang. "Specialized Medial Prefrontal–Amygdala Coordination in Other-Regarding Decision Preference." Nature Neuroscience (First published: February 24, 2020) DOI: 10.1038/s41593-020-0593-y