Deriving within-person estimates of delta-beta coupling: A novel measure for identifying individual differences in emotion and neural function in childhood.

Delta-beta coupling is increasingly used to understand early emotional development. However, little is known about the development of the coupling, limiting its utility for identifying normative or aberrant functioning. We used a prospective longitudinal sample (N = 122) to compare measures of within-person and between-person coupling between ages 3 and 5, track the developmental trajectory of coupling, identify individual differences in patterns of development, and explore emotion-related predictors and outcomes of discrete developmental patterns. Within-person measures, limited in overall utility, were most useful when (1) statistical approaches produced more homogenous groups within the overall sample (extreme groups or latent classes) or (2) the full developmental course was considered. We found two trajectories of change in frontal coupling and three trajectories of change in parietal coupling. Coupling trajectories were predicted by observed fear and approach/avoidance at age 3. In addition, high levels of frontal coupling at age 3 that declined and then levelled out through age 5 were associated with lower levels of internalizing by age 5. This work provides a foundation for understanding normative change in delta-beta coupling across the preschool years and useful insight for the use of this metric in future work.