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 circuitry between the locus coeruleus (LC) and dorsolateral prefrontal cortex (dlPFC). The effect was not explained by differences in perception or response caution, but by a stimulus-independent evaluative component of evidence accumulation called drift intercept. The findings suggest that the well-known positivity bias in aging has a specific neural circuit signature, with implications for understanding emotional regulation across the lifespan.
Researchers used fMRI and computational modeling to examine how people from late childhood through middle adulthood resolve emotionally ambiguous facial expressions — morphed images on a continuum from angry to happy — into categorical judgments. Positive interpretive bias increased systematically with age, and drift-diffusion modeling pinpointed this shift to the drift intercept parameter, reflecting a stimulus-independent evaluative tendency rather than sharper perception, a shifted starting point, or greater 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 processing uncertainty and offers a circuit-level account of why older individuals tend to see the world through a more positive emotional lens.
What's missing
The study is a preprint posted on bioRxiv and has not yet undergone formal peer review. The sample spans late childhood through middle adulthood, so it is unclear whether findings generalize to older adults, where positivity bias and LC neurodegeneration are most clinically relevant. The study does not establish causality between LC-dlPFC circuitry and positive bias.
What different sources said
- bioRxivCenter
Positive Interpretation of Emotional Ambiguity Across Development: LC-dlPFC Circuitry
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