Age-Related Changes in Positive Interpretation of Ambiguous Emotions Linked to Brain Circuitry
A neuroimaging study found that people increasingly interpret emotionally ambiguous facial expressions as happy rather than angry as they age from late childhood through middle adulthood, and this shift is tied to a specific brain circuit. The effect was traced to a decision-making component called drift intercept — an evaluative bias in evidence accumulation — rather than differences in perception or response style. The findings suggest the locus coeruleus (LC) and dorsolateral prefrontal cortex (dlPFC) circuit plays a key role in how emotional ambiguity is resolved across development.
Researchers used fMRI and computational modeling to examine how people from late childhood through middle-aged adulthood interpret facial expressions that morph between angry and happy. Positive interpretive bias increased systematically with age, and drift-diffusion modeling localized this shift to the drift intercept parameter — a stimulus-independent evaluative component — rather than perceptual sensitivity, starting point, or response caution. At the neural level, coupling between the locus coeruleus (LC) and the dorsolateral prefrontal cortex (dlPFC) was most strongly associated with positive bias in middle-aged adults. Trial-level analyses revealed that dlPFC carried a clearer moment-to-moment evaluative signal, while the LC contributed through slower temporal dynamics quantified by the Hurst exponent. Notably, higher LC structural integrity was associated with lower temporal persistence in LC activity and, in turn, more negative LC-dlPFC coupling, suggesting that the physical health of this brainstem nucleus shapes how it communicates with prefrontal regions. The study extends a growing body of work implicating LC-prefrontal connectivity in ambiguity processing and frames age-related positivity as a circuit-level phenomenon rather than a simple perceptual or motivational shift.
What's missing
The study is a preprint posted to bioRxiv and has not yet undergone peer review, so findings should be interpreted with caution. The cross-sectional design (comparing different age groups rather than following individuals over time) limits causal inference about developmental change. The sample's age range (late childhood to middle adulthood) leaves open whether the same LC-dlPFC mechanisms extend into older adulthood, where positivity effects and LC neurodegeneration are both well-documented. The study does not address whether the observed positive bias has adaptive or maladaptive consequences in real-world social contexts.
What different sources said
- bioRxivCenter
Positive Interpretation of Emotional Ambiguity Across Development: LC-dlPFC Circuitry
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