Summary: New research shows that damage to specific areas of the medial prefrontal cortex (mPFC) increases both emotionality and sensitivity to emotional behavior in others. Participants with mPFC lesions were more likely to choose immediate rewards and were more likely to be influenced by people who made impulsive decisions.
Distinct regions of the medial prefrontal cortex (mPFC) were found to independently determine general motivation and sensitivity to social influence. These findings offer new insights into how brain damage affects decision-making and may have implications for understanding misinformation and financial decisions.
Key data:
- Increased speed: Damage to the ventromedial prefrontal cortex leads to more impulsive decisions.
- Greater social influence: Damage to the dorsomedial prefrontal cortex increases sensitivity to the emotional behavior of others.
- Broader implications: The findings help explain how brain structure affects external influences and risk-taking in decision-making.
Source: University of Birmingham
People who have damage to a specific part of the brain are more likely to be emotional. In addition, new research suggests that such damage also makes them more susceptible to influence from others.
In a new study published in PLOS Biology , a research team found that damage to several parts of the medial prefrontal cortex (mPFC) was associated with the influence of others on impulsive decision-making, while another area was linked to choosing a small reward rather than waiting for a larger reward.
A team from the University of Birmingham, the University of Oxford and the Julius Maximilian University of Würzburg studied participants with brain damage to see if they were more influenced by the preferences of others.
The team worked with 121 participants, 33 of whom had focal damage to the mPFC, 17 had lesions in other parts of the brain, and 71 participants had no brain damage but were the same age.
Researchers presented participants with a series of options to gauge their overall motivation. They were then presented with the same options and shown what other people would choose. Some made very impulsive decisions, while others chose to make more deliberate choices.
Participants with damage to the medial prefrontal cortex (mPFC) generally showed greater motivation. The team was also surprised to find that these participants were much more sensitive to the influence of influential people than the healthy individuals.
Professor Patricia Lockwood, from the University of Birmingham and lead author of the study, said:
The findings are important because we learn about the desires of others every day, and this influences our own preferences. We used an experiment to observe whether social influence occurs when people act more emotionally or when they withdraw.
The study revealed a crucial function of a specific brain region: when this area is damaged, it causes individuals to become more vulnerable to influence from people displaying intensely emotional behavior.
Crucially, this heightened susceptibility to influence was found to be selective, as the affected individuals did not show the same vulnerability when interacting with others who exhibited more moderate or reserved behavior.
“We also found that brain damage in another part of the brain makes you more impressionable in general, even before you’re influenced by another person.”
“Taken together, our research suggests that the influence of others has a specific neural basis that can affect everything from how we perceive misinformation to how other people can influence our own financial preferences.”
Patience
The team also used a combination of mathematical models and existing brain scans to determine the size and location of lesions in the medial prefrontal cortex. The results suggest that different regions of the medial prefrontal cortex (mPFC) control specific affective effects.
Research has shown that lesions in the dorsomedial area, located at the top of the prefrontal cortex (PFC), have the greatest impact on the social effects of movement.
Meanwhile, lesions in the ventromedial inferior part of the PFC were found to have a greater effect on overall speed, before social influence.
Zhilin Su, from the University of Birmingham and lead author of the study, said:
The researchers were uniquely positioned to analyze a large group of participants who had exceptionally specific damage confined to the medial prefrontal cortex. This highly targeted patient sample was critical to the study’s goal.
This specific focus allowed the team to precisely investigate the core question of whether this particular brain damage directly affects the degree to which those individuals are susceptible to external influence from other people.
“We found that people can still recognize others’ preferences after suffering a loss, but they are greatly affected by them.”
About this TBI and impulsivity research news
Author: Tim Mayo
Source: University of Birmingham
Contact: Tim Mayo – University of Birmingham
Image: The image is credited to StackZone Neuro
Original Research: Open access.
“Dorsomedial and ventromedial prefrontal cortex lesions differentially impact social influence and temporal discounting” by Patricia Lockwood et al. PLOS Biology
Abstract
Lesions targeting the dorsomedial prefrontal cortex (dmPFC) and the ventromedial prefrontal cortex (vmPFC) have distinct effects on behavior.
This research demonstrates that damage to these two closely related, yet functionally separate, areas of the prefrontal cortex results in different consequences.
Specifically, the damage differentially affects an individual’s susceptibility to social influence (how much their judgments or decisions are changed by others) and their tendency toward time discounting (how much they devalue future rewards compared to immediate ones).
The medial prefrontal cortex (mPFC) has long been linked to economic and social decision-making in neuroimaging studies.
Several debates have raised the question of whether different regions of the ventral medial (vmPFC) and dorsal (dmPFC) prefrontal cortex have specific functions or whether there is a gradient of social and non-social cognition.
tested an unusually large sample of rare participants with focal damage in the mPFC ( N = 33), individuals with lesions in other locations ( N = 17), and healthy controls ( N = 71) ( N = 121).
Participants performed a time discounting task to estimate their baseline time discounting preferences before learning the preferences of two other individuals, one more time-consuming and the other more patient.
Using Bayesian computational models, we estimate the fundamental discount rate and sensitivity to social influence after knowing the economic preferences of others.
Damage to the medial prefrontal cortex (mPFC) resulted in increased sensitivity to powerful social influence compared to healthy controls. General sensitivity to social influence was also increased compared to individuals with lesions in other parts of the body.
Importantly, voxel-based lesion symptom mapping (VLSM) of computational parameters showed that this increased sensitivity to social influence was specifically attributed to damage in the dmPFC (area 9; permutation-based threshold-free cluster enhancement (TFCE) p < 0).
In contrast, lesions in the vmPFC (areas 13 and 25) and ventral striatum were associated with a preference for obtaining more immediate rewards ( P < 0.05 based on TFCE).
We show that the dorsomedial prefrontal cortex (dmPFC) is commonly involved in sensitivity to social influence, and that several ventral regions of the medial prefrontal cortex (mPFC) are involved in temporal discounting. These results provide useful evidence.
