Prenatal experience of maternal walking rhythm on head postural control

Temporal regularities (tempos) are omnipresent from the earliest age in the physical and social environment of an infant's life. It is now well documented that fetuses and infants are capable of perceiving and adapting to the rhythms of their physical and social environment (Provasi et al., 2014) and that this skill supports their cognitive and social development (Bobin-Bègue, 2019, 2020). From then on, the question that arises is how this early experience is established. One of the most important and earliest experiences of tempos during development is the maternal walking rhythm, firstly during gestation and then during carrying in the postnatal period. The vestibular system is functional fairly early in gestation (e.g. Lecanuet & Schaal, 2002). In addition, one of the first stages in subsequent development is one that requires reliance on vestibular information in order to stabilise head posture, in particular to enable the development of visuomotor coordination. We therefore put forward the hypothesis that at 2 months, the infant's head support is more effective when the mother, who is carrying the infant, walks at her usual pace rather than at a faster or slower pace, because the infant has more experience of her mother's usual walking pace (we assume that this is also the pace that the infant was most often confronted with during gestation). One way of verifying this hypothesis is to test whether infants anticipate their muscular control more when they are carried by their mothers walking at a usual pace compared with a faster or slower pace. In this study, 17 mothers carried their infants (mean age 57 days) vertically against them while they walked in a straight line. Using a wireless electromyographic recording device (a method already used in other infant studies, e.g. Addyman et al., 2016), contractions of the sternocleidomastoid muscle (a muscle strongly involved in head stability) were recorded synchronously in the infant and their mother. The recordings were made under 3 conditions, in a counterbalanced order between the participants: a fast, normal or slow walking rhythm (at her discretion). These recordings were supplemented by video recordings to check for the absence of artifacts and to associate the different phases of the experiment. The aim of the analyses is to compare whether the muscle signals from the infant and the mother are closer when the mother walks at her usual pace. The analyses are about to begin. The data will be pre-processed using the "eda_clean" function in the neurokit2 package (Makowski et al., 2021). The results of this study, if they confirm the hypothesis, would support the more general hypothesis that tempo, in addition to supporting the development of motor and socio-cognitive skills, would support continuity between mother and child through temporal characteristics (echoed by rocking and singing in parenting practices). The results of this study will therefore be used to support a larger-scale research project on the question of a vestibular temporal basis, in the form of tempo, for the establishment of an early relationship between mother and infant.