Summary: New research finds that damage to specific regions of the medial prefrontal cortex (mPFC) increases both a person’s general impulsivity and their vulnerability to the impulsive choices of others. Participants with focal mPFC lesions favored immediate rewards and were more likely to adopt impulsive choices after learning what others selected.
The study distinguishes separate roles within the mPFC: one region primarily modulates baseline impulsivity, while another governs susceptibility to social influence. These insights advance our understanding of how localized brain damage alters decision-making, with potential implications for vulnerability to misinformation and financial decision behavior.
Key Facts:
- Increased impulsivity: Lesions in the ventromedial prefrontal cortex (vmPFC) are associated with a stronger preference for immediate rewards.
- Greater social influence: Lesions in the dorsomedial prefrontal cortex (dmPFC) make people more susceptible to others’ impulsive choices.
- Broader implications: The dissociation within mPFC regions helps explain how brain structure shapes susceptibility to outside influence and affects economic and social decision-making.
Source: University of Birmingham
Overview: People with damage to specific mPFC regions are not only more impulsive but also more easily swayed by others’ impulsive behavior, according to research published in PLOS Biology. The international team—based at the University of Birmingham, University of Oxford, and Julius-Maximilians-University Würzburg—tested whether localized brain lesions change how individuals learn from and conform to other people’s preferences.
The researchers recruited 121 people: 33 with focal mPFC damage, 17 with lesions in other brain areas, and 71 healthy age-matched controls. Participants first completed a temporal discounting task to measure baseline impulsivity—choosing between smaller-sooner and larger-later monetary rewards. Later, the same choices were presented along with information about two other people’s preferences: one person who preferred immediate rewards (more impulsive) and one who preferred delayed rewards (more patient).
Overall, people with mPFC damage showed higher baseline impulsivity. Crucially, those with damage in the dorsomedial mPFC were markedly more influenced by others who made impulsive choices, whereas lesions in ventromedial mPFC and ventral striatum were linked to a stronger personal bias toward immediate rewards even before social information was shown.
To quantify these effects, the team applied Bayesian computational models to estimate individual discounting rates and susceptibility to social influence after participants learned about others’ preferences. Voxel-based lesion-symptom mapping localized the social susceptibility effect to the dmPFC (area 9) and linked increased temporal discounting to vmPFC regions (areas 13 and 25) and ventral striatum.
Professor Patricia Lockwood of the University of Birmingham, senior corresponding author of the study, emphasized the everyday relevance: “We constantly learn from what other people want, and that learning shapes our own preferences. Our experiment separated when people are influenced by others who behave impulsively from when they are influenced by people who are more patient. We found that damage to a specific mPFC area increases susceptibility to impulsive social signals, while damage to another area increases impulsivity in general.”
Lead author Zhilin Su added: “Having a relatively large sample of participants with localized mPFC damage allowed us to test whether this damage alters how people are influenced by others. Even though many participants could still learn others’ preferences, those with mPFC lesions were more likely to adopt those preferences, especially when others behaved impulsively.”
Patience and the mPFC
The study’s combination of behavioral testing, computational modeling, and lesion mapping supports a functional dissociation within the mPFC. Dorsomedial regions appear causally involved in regulating social susceptibility to impulsive behavior, while ventromedial regions and the ventral striatum are more directly tied to preferences for immediate reward—temporal discounting. This dissociation clarifies debates about whether different mPFC subregions have specialized roles or support a gradient of social and nonsocial cognition.
About this TBI and impulsivity research news
Author: Tim Mayo
Source: University of Birmingham
Contact: Tim Mayo – University of Birmingham
Image: Image credited to Neuroscience News
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
Dorsomedial and ventromedial prefrontal cortex lesions differentially impact social influence and temporal discounting
The medial prefrontal cortex (mPFC) has long been associated with economic and social decision-making. Debates persist over whether distinct ventral and dorsal mPFC regions serve specific functions or form a gradient supporting social and nonsocial cognition. To address this, the authors tested a large sample of participants with focal mPFC damage (N = 33), people with lesions elsewhere (N = 17), and healthy controls (N = 71), using a temporal discounting paradigm followed by exposure to the preferences of two other individuals—one impulsive and one patient.
Bayesian computational modeling estimated baseline discounting and susceptibility to social influence. Lesions to the mPFC increased susceptibility to impulsive social influence relative to healthy controls and increased overall social susceptibility compared to people with lesions elsewhere. Voxel-based lesion-symptom mapping linked heightened social susceptibility specifically to the dorsomedial PFC and associated increased preference for immediate rewards with ventromedial PFC and ventral striatum damage. These findings provide causal evidence for distinct roles of dmPFC and vmPFC in social influence and temporal discounting.