The neural mechanisms supporting habituation to audiovisual association in infants: An fNIRS and looking time study

Abstract

Habituation, the decrease in behavioral response with repeated presentation of a stimulus, has been instrumental in assessing learning in infants for decades. Yet, despite its prominence in developmental research, its underlying neural mechanism(s) remain to be understood. Importantly, the current study allows infants to control presentation to reach a behaviorally-defined habituation criterion. Using functional near-infrared spectroscopy (fNIRS), we recorded infants’ neural responses during an audio-visual association task, analyzing changes in neural activity (HbO concentration) in neuro-anatomically defined regions of interest (the temporal, occipital, and frontal cortices) as well as functional connectivity between these regions. Though we hypothesized a decrease in neural activity over the process of learning and decreases in the functional connectivity between regions of interest and particularly between the temporal and occipital regions, results yielded no significant behavioral or neural trends. Overall, this work represents a novel and challenging integration of methods: The concurrent investigation of behavioral and neural measures of learning in young infants will catalyze an understanding of learning mechanisms available early in life and the developmental change of these mechanisms.