Distinct neural patterns of valence and arousal in the developing brain: A representational similarity analysis of...

How children and adolescents encode the affective meaning of visual stimuli remains poorly understood. A key reason is that valence and arousal are inherently correlated across affective stimuli and thus confounded in the categorical contrasts mostly used in emotion research. Here, in a secondary analysis of a previously collected MEG dataset, we dissociate the contributions of valence and arousal in emotional processing by applying partial representational similarity analysis (RSA) to magnetoencephalography (MEG) data from 57 typically developing children and adolescents (5 - 18 years old) viewing pictures from the Nencki Affective Picture System. Source-localized responses were first estimated on a volumetric grid, after which we tested, across regions and time windows, whether similarity in neural activity patterns tracked similarity in valence or arousal ratings while controlling for their shared variance. Valence emerged as the primary organizing dimension of neural representations in this sample, with effects detectable in frontotemporal and salience regions within the first 100 ms and sustained over time in the lateral prefrontal cortex. These responses formed a distributed representational network that progressively engaged higher-order evaluative regions. In contrast, arousal contributed transiently through a distinct network that only intermittently overlapped with valence-related activity. Together, these findings indicate that valence predominantly structures affective representations in this pediatric sample, whereas arousal exerts a weaker and more limited influence. This work provides an initial characterization of affective representational structure in this sample of children and adolescents, that if replicated, may inform future reference framework for identifying deviations associated with conditions such as autism spectrum disorder.