Our ability to want to help others is controlled by a very specific area in the brain, according to a study published in the journal Nature Human Behaviour.
Understanding how we make decisions to help those around us is important to learn about social interactions. It also helps us understand decisions to tackle important subjects such as climate change and international conflict.
Now, a team from the University of Birmingham and the University of Oxford, UK, showed how a region called the ventromedial prefrontal cortex (vmPFC) has a critical role in helping prosocial behaviors. “Prosocial behaviours are essential for addressing global challenges. Yet helping others is often effortful, and humans are averse to effort. Understanding how effortful helping decisions are processed in the brain is extremely important,” said Professor Patricia Lockwood.
This area, located right at the front of the brain, is known to be important for decision-making and other executive functions. Previous studies have shown that the vmPFC is active when people make choices involving a trade-off between the rewards available and the effort required to obtain rewards. However, these techniques can’t show if this part of the brain is essential for these functions.
For this study, three groups of participants were recruited: 25 patients with vmPFC damage, 15 with damage elsewhere in the brain, and 40 healthy people.
Each participant met another person anonymously and then completed a decision-making task to measure how willing they were to engage in physical effort (squeezing a grip force device) to earn points for themselves and the other person. Participants were allowed to meet the person they would be working for, but researchers hid any information about the other person that could affect decision-making. Each task varied in how many points participants could get for themselves or the other person and how much force they would have to exert to obtain the reward. This way, researchers could measure the impact of reward and effort separately, which was then used to quantify each person’s motivation.
The results showed that the vmPFC was necessary to motivate others. Patients with vmPFC damage were less willing to help others, exerted less force, and earned fewer points to help others compared to the control groups.
Using a technique called lesion symptom mapping enabled the researchers to identify more specifically what subregions of the vmPFC are involved in social behavior and unwillingness to help others. Curiously, damage to a nearby but different subregion made people relatively more willing to help.
“As well as better understanding prosocial motivation, this study could also help us to develop new treatments for clinical disorders such as psychopathy, where understanding the underlying neural mechanisms can give us new insights into how to treat these conditions,” said author Dr Jo Cutler. “This region of the brain is particularly interesting because we know that it undergoes late development in teenagers and also changes as we get older,” added Professor Lockwood. “It will be really interesting to see whether this area of the brain can also be influenced by education – can we learn to be better at helping others?”
Lockwood, P.L., Cutler, J., Drew, D. et al. Human ventromedial prefrontal cortex is necessary for prosocial motivation. Nat Hum Behav (2024). https://doi.org/10.1038/s41562-024-01899-4