Characterising longitudinal dynamics of infant neurodevelopment using functional change point detection
SignificanceHabituation is an early-developing cognitive process linked to learning, typically reflected in functional near-infrared spectroscopy (fNIRS) studies as a reduction in evoked hemodynamic response amplitude. Conventional fNIRS analyses rely on linear time-invariance assumptions, potentially limiting insight into how responses evolve across repeated stimulus presentations. AimTo determine whether functional change point (FCPt) detection can characterize trial-specific changes in the infant hemodynamic response and reveal developmental differences in habituation timing. ApproachFunctional data analysis (FDA) treats entire response curves as statistical objects. Within this framework, FCPt detection identifies statistically significant structural shifts in the mean response across trials. FCPt detection with wild binary segmentation was applied to infant fNIRS data (n = 204) collected from infants living in rural Gambia at 5-, 8-, and 12-months of age during a habituation and novelty detection paradigm. ResultsSignificant changes were identified within auditory cortical regions. A high proportion of detected change points corresponded to decreases in response magnitude at 8- and 12-months. Ordinal regression revealed an age-related shift toward earlier occurrence of decreasing change points, indicating that older infants completed habituation sooner within the trial sequence. ConclusionFCPt detection provides temporal information on the infant hemodynamic response unavailable to conventional analysis. This additional information has revealed a previously overlooked developmental change in the habituation response during the first year of infancy.