Growing in generosity? The Effects of Giving Magnitude, Target, and Audience on the Neural Signature of Giving in Adolescence

Decoding the altruistic brain: An ALE meta-analysis of the functional localization of giving behaviors

Neuroimaging studies on prosocial decision-making frequently employ a costly giving paradigm, whereas there is a lack of consensus on the broader differences underlying various altruistic giving tasks. This study explores the neural substrates of altruistic giving through an ALE meta-analysis of 65 fMRI studies with 2803 participants. Altruistic giving tasks were categorized into Dictator Game (DG), Charitable Donation (CD), and Pain versus Gain (PvsG). The meta-analysis identified consistent activation in core brain regions, including the ventromedial prefrontal cortex (vmPFC), anterior cingulate cortex (ACC), and insula, which are involved in value computation, conflict monitoring, and emotional processing. Task-specific analyses revealed that the DG task activated the right dorsomedial prefrontal cortex (dmPFC) and presupplementary motor area (pre-SMA), indicating cognitive control of fairness. The CD task showed significant activation in the nucleus accumbens (NAcc) and the second visual cortex, reflecting socio-cognitive evaluation based on context and stimuli. The PvsG task uniquely activated the vmPFC and orbitofrontal cortex (OFC), suggesting rapid moral-emotional trade-offs under urgency. These findings indicate that altruistic giving is context-dependent, shaped by specific task demands. Future research should integrate computational modeling with neuroscientific data and explore individual differences and real-world applications.

Brain Stimulation of Dorsolateral Prefrontal Cortices Influences Impulsivity in Delay Discounting Choices

Intertemporal decision-making is pivotal for human interests and health. Recently, studies instructed participants to make intertemporal choices for both themselves and others, but the specific mechanisms are still debated. To address the issue, in the current study, the cost-unneeded conditions (i.e., "Self Immediately - Self Delay" and "Other Immediately - Other Delay" conditions) and the cost-needed conditions (i.e., "Self Immediately - Other Delay" and "Self Delay - Other Immediately" conditions) were set with the identity of OTHER being a stranger. We manipulated the magnitude of reward (Experiment 1) and disrupted the activation of the dorsolateral prefrontal cortex with repetitive transcranial magnetic stimulation (rTMS; Experiment 2). We found that both the behavioral and rTMS manipulations increased smaller but sooner choice probability via reducing self-control function. The reduced self-control function elicited by rTMS affected both self- and other-related intertemporal choices via increasing the choice preference for smaller but sooner reward options, which may help people deeply understand the relationship between self- and other-related intertemporal choices in processing mechanism, especially when the OTHER condition is set as a stranger.

Age-related changes in ventrolateral prefrontal cortex activation are associated with daily prosocial behaviors two years later

As adolescents acquire agency and become contributing members of society, it is necessary to understand how they help their community. Yet, it is unknown how prosocial behavior develops in the context of community-based prosocial behaviors that are relevant to adolescents, such as donating time to charities. In this longitudinal functional magnetic resonance imaging study, adolescents (N=172; mean age at wave 1=12.8) completed a prosocial task annually for three years (N=422 and 375 total behavioral and neural data points, respectively), and 14 days of daily diaries reporting on their prosocial behaviors two years later. During the task, adolescents decided how many minutes they would donate to a variety of local charities. We found that adolescents donated less time to charities from early to mid adolescence. Longitudinal whole-brain analyses revealed declines in ventrolateral prefrontal cortex (vlPFC) activation, as well as inverted U-shaped changes in precuneus activation when adolescents donated their time from early to mid adolescence. A less steep decrease in vlPFC activation predicted greater real-life prosocial behaviors in youth's daily lives two years later. Our study elucidates the neurodevelopmental mechanisms of prosocial behavior from early to mid adolescence that have enduring effects on daily prosocial behaviors in late adolescence.

Learning whom not to trust across early and middle adolescence: A longitudinal neuroimaging study to trusting behavior involving an uncooperative other

Longitudinal changes in trusting behavior across adolescence and their neural correlates were examined. Neural regions of interest (ROIs) included the medial prefrontal cortex (mPFC), dorsal anterior cingulate cortex (dACC), left anterior insula (AI), bilateral ventral striatum (VS), and right dorsal striatum (DS). Participants (wave 1 age: M = 12.90) played the investor in a Trust Game with an uncooperative trustee three times (1-year interval). Analyses included 77 primarily Dutch participants (33 females). Participants decreased their investments with wave. Furthermore, activity was heightened in mPFC, dACC, and DS during investment and repayment, and in right VS (investment) and AI (repayment). Finally, DS activity during repayment increased with wave. These findings highlight early-middle adolescence as an important period for developing sensitivity to uncooperative behavior.

Neural Mechanisms Underlying Trust to Friends, Community Members, and Unknown Peers in Adolescence

Trust plays an important role during adolescence for developing social relations. Although prior developmental studies give us insight into adolescents' development of differentiation between close (e.g., friends) and unknown (e.g., unknown peers) targets in trust choices, less is known about the development of trust to societal targets (e.g., members of a community organization) and its underlying neural mechanisms. Using a modified version of the Trust Game, our preregistered fMRI study examined the underlying neural mechanisms of trust to close (friend), societal (community member), and unknown others (unknown peer) during adolescence in 106 participants (aged 12-23 years). Adolescents showed most trust to friends, less trust to community members, and the least trust to unknown peers. Neural results show that target differentiation in adolescents' trust behavior is associated with activity in social brain regions implicated during mentalizing, reward processing, and cognitive control. Recruitment of the medial prefrontal cortex (mPFC) and OFC was higher for closer targets (i.e., friend and community member). For the mPFC, this effect was most pronounced during no trust choices. Trust to friends was additionally associated with increased activity in the precuneus and bilateral temporal parietal junction. In contrast, bilateral dorsolateral prefrontal cortex and anterior cingulate cortex were most active for trust to unknown peers. The mPFC showed increased activity with age and consistent relations with individual differences in feeling needed/useful.

Corticostriatal Connectivity during Prosocial Decision-making Relates to Giving Behavior during Adolescence

Prosocial behavior during adolescence becomes more differentiated based on the recipient of the action as well as the perceived value or benefit, relative to the cost to self, for the recipients. The current study investigated how functional connectivity of corticostriatal networks tracked the value of prosocial decisions as a function of target recipient (caregiver, friend, stranger) and age of the giver, and how they related to giving behavior. Two hundred sixty-one adolescents (9-15 and 19-20 years of age) completed a decision-making task in which they could give money to caregivers, friends, and strangers while undergoing fMRI. Results indicated that adolescents were more likely to give to others as the value of the prosocial decision (i.e., the difference between the benefit to other relative to the cost to self) increased; this effect was stronger for known (caregiver and friends) than unknown targets, and increased with age. Functional connectivity between the nucleus accumbens (NAcc) and OFC increased as the value of the prosocial decisions decreased for strangers, but not for known others, irrespective of choice. This differentiated NAcc-OFC functional connectivity during decision-making as a function of value and target also increased with age. Furthermore, regardless of age, individuals who evinced greater value-related NAcc-OFC functional connectivity when considering giving to strangers relative to known others showed smaller differentiated rates of giving between targets. These findings highlight the role of corticostriatal development in supporting the increasing complexity of prosocial development across adolescence.

Longitudinal neural and behavioral trajectories of charity contributions across adolescence

This study examined the development of prosocial charity donations and neural activity in the ventral striatum when gaining rewards for self and for charity. Participants 10-22 years (95% European heritage) participated in three annual behavioral-fMRI waves (T1: n = 160, T2: n = 167, T3: n = 175). Behaviorally, donations to charity as measured with an economic Dictator Game increased with age. Perspective taking also increased with age. In contrast, self-gain and charity-gain enjoyment decreased with age. Ventral striatum activity was higher for rewards for self than for charity, but this difference decreased during adolescence. Latent growth curve models revealed that higher donations were associated with a smaller difference between ventral striatum activation for self and charity. These findings show longitudinal brain-donations associations in adolescence.

Temporal discounting for self and friends in adolescence: A fMRI study

Adolescence is characterized by impulsivity but also by increased importance of friendships. This study took the novel perspective of testing temporal discounting in a fMRI task where choices could affect outcomes for 96 adolescents (aged 10-20-years) themselves and their best friend. Decisions either benefitted themselves (i.e., the Self Immediate - Self Delay' condition) or their friend (i.e., 'Friend Immediate - Friend Delay' condition); or juxtaposed rewards for themselves and their friends (i.e., the 'Self Immediate - Friend Delay' or 'Friend Immediate - Self Delay' conditions). We observed that younger adolescents were more impulsive; and all participants were more impulsive when this was associated with an immediate benefit for friends. Individual differences analyses revealed increased activity in the subgenual anterior cingulate cortex extending in the ventral striatum for immediate relative to delayed reward choices for self. Temporal choices were associated with activity in the prefrontal cortex, parietal cortex, insula, and ventral striatum, but only activity in the right inferior parietal lobe was associated with age. Finally, temporal delay choices for friends relative to self were associated with increased activity in the temporo-parietal junction and precuneus. Overall, this study shows a unique role of the social context in adolescents' temporal decision making.

Giving to others and neural processing during adolescence

Adolescence is marked by an increased sensitivity to the social environment as youth navigate evolving relationships with family, friends, and communities. Prosocial behavior becomes more differentiated such that older adolescents increasingly give more to known others (e.g., family, friends) than to strangers. This differentiation may be linked with changes in neural processing among brain regions implicated in social decision-making. A total of 269 adolescents from 9–15 and 19–20 years of age completed a decision-making task in which they could give money to caregivers, friends, and strangers while undergoing functional magnetic resonance imaging (fMRI). Giving to caregivers and friends (at a cost to oneself) increased with age, but giving to strangers remained lower and stable across age. Brain regions implicated in cognitive control (dorsolateral and ventrolateral prefrontal cortex) showed increased blood-oxygen-level-dependent (BOLD) activation with increasing age across giving decisions to all recipients; regions associated with reward processing (ventral striatum and ventral tegmental area) showed increased activation across all ages when giving to all recipients. Brain regions associated with social cognition were either not active (dorsomedial prefrontal cortex) or showed reduced activation (temporal parietal junction and posterior superior temporal sulcus) when giving to others across all ages. Findings have implications for understanding the role of brain development in the increased complexity of social decision-making during adolescence.