Sensorimotor cascades: Integrating real-time movement dynamics during the sleep and awake periods of human infants

During the first year of life, a human infant’s 24-hour day consists of an intermittent cycling of sleep periods and awake periods. The average 6-month-old human infant sleeps for a cumulative 16 hours of each 24-hour day. Yet, knowledge about the emergence of infants’ sensorimotor skills – uncontrolled sitting, crawling, reaching, walking – is more often informed by the smaller proportion of an infant’s day when they are awake. Furthermore, along the way to the mastery of new sensorimotor skills, which are typically documented in traditional laboratory tasks or parent reports, there are complex sensorimotor dynamics unfolding at fast, moment-to-moment timescales and occurring throughout all 24 hours of an infant’s day. The overarching aim of this proposal is to link infant sensorimotor dynamics during sleep periods to embodied sensorimotor experiences during real world awake periods to ultimately map a more comprehensive set of pathways of sensorimotor development.

No studies to date have systematically integrated real-time movement dynamics during the sleep and awake periods of human infants and evaluated concurrent associations or predictive relationships. Studies of sensorimotor development have traditionally neglected integrating the sleep periods that account for a large proportion on an infant’s 24-hour day. Human infants spontaneously move around quite a lot during sleep periods and these movements are not random. Myoclonic twitches are discrete movements of facial features, arms, legs, hands, and feet that occur during sleep. The spatiotemporal dynamics of myoclonic twitches provide sensory feedback and support functional connectivity throughout the nervous system. It is therefore hypothesized that the sensorimotor dynamics of myoclonic twitches are functionally relevant for sensorimotor development and provide a foundation for more complex, specialized sensorimotor patterns and skills, what we call a sensorimotor cascade.

In a prospective, longitudinal design, we propose to examine the roles that movement dynamics during sleep periods and sensorimotor behaviors during awake periods play in trajectories of sensorimotor development at 4, 6, and 8 months of age. First, we identify concurrent associations between spatiotemporal dynamics of movements during sleep and patterns of body movements and body positions during awake periods using novel wearable sensor technology and machine learning algorithms for body position classification. We then determine predictive associations between spatiotemporal dynamics of movements during sleep periods at 4 and 6 months with dynamics patterns of body positions during awake periods at 6 and 8 months, accordingly. Finally, we will examine how movement dynamics during sleep and awake periods provide a developmental landscape for the emergence of new sensorimotor skills like reaching and crawling.

This proposal leverages the PI’s scientific expertise in quantifying the dynamics of behavior throughout multiple timescales of development, emerging wearable sensor technologies with rigorous computational applications, and a key team of collaborators to explore the relationships between dynamic movement patterns during sleep periods and profiles of naturalistic sensorimotor behaviors during awake periods. Understanding how the spatiotemporal organization of body movements during sleep periods is associated with naturalistic sensorimotor behaviors during awake periods can pave the way for a richer, more complete understanding of sensorimotor development.