Co-regulating with your child: exploring parent-infant Interpersonal Neural Synchrony after an interactive rupture

During the first thousand days, the infant’s ability to iteratively co-regulate their neurophysiological states with the primary caregiver – better known as interpersonal neural synchrony (INS) – is believed to be a neuromarker for social interaction. Electroencephalograph (EEG) hyperscanning is a novel experimental paradigm that allows the simultaneous recording of neural activity between two interactive partners. Recent studies showed that behavioral synchrony in parent-infant dyads is established through repeated cycles of matched and mismatched states, which can be observed during the Face-to-Face Still-Face (FFSF) procedure. While the literature highlighted significant associations between INS and a series of interactive behaviors, no study to date has assessed changes in INS during experimentally induced interactive ruptures. The present dissertation aims at assessing how directed and non-directed INS between parents and infants changes before and after an interactive rupture. Additionally, the study assessed whether arbitrary decision-making during dual EEG data pre-processing impacted measures of INS. Parents and their nine-month-old infants had their brain activity measured via the EEG hyperscanning paradigm while they engaged in an adapted FFSF procedure. Interactive behaviors were microanalytically coded in Noldus. INS was computed using cross-frequency phase locking value (PLV; see Chapter 3), partial directed coherence (PDC; see Chapter 4), imaginary coherence (ICoh) and weighted phase lag index (wPLI; see Chapter 5). Our studies revealed the following: 1. The FFSF produced significant changes in PDC directionality and increases in wPLI from Play to Reunion; 2. Arbitrary decision-making during EEG data pre-processing has limited impact on INS metrics such as PLV; 3. Parent-infant INS is significantly correlated with dyadic behaviors, and 4. Significant associations between INS and dyadic behaviors were focused in fronto-posterior and centro-frontal clusters. The findings provide preliminary evidence regarding the association between INS and dyadic reparations, and reinforce the notion that biobehavioral synchrony and INS can mutually facilitate one another.