Age-related differences in the activation of the mentalizing- and reward-related brain regions during the learning of others' true trustworthiness

Behavioral studies suggest that older adults may be less adept than younger adults at remembering information contradicting their first impressions about others' trustworthiness. To identify the neural bases associated with such age-related differences, we measured the brain activity of older and younger participants using functional magnetic resonance imaging while they processed feedback on whether their initial trustworthiness impressions of stimulus persons, whose true trustworthiness had been predetermined, were right or wrong. Of special interest was the activation in mentalizing- (e.g., medial prefrontal cortex) and reward-related brain regions (e.g., striatum), which are known to be involved in impression formation and feedback learning, respectively. The reduction in the striatal responses to impression-contradicting versus impression-confirming feedback was greater in older than in younger participants. The activation of some mentalizing-related regions (medial prefrontal cortex and precuneus) was lower in older than younger participants; however, it was not modulated by impression-feedback congruency. The results suggest that age-related differences in the striatum engagement may underlie older adults' inefficiency in learning impression-incongruent information about others' trustworthiness.