Research

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  • Kick Start: Learning to Move the World

    We are using an infant mobile to shape the amount and the coordination of infant kicking in the earliest months of life. The infants learn that their leg actions can activate the movement and music in the mobile. The "contingency" that is learned is fundamental in development as infants learn that their actions have consequences on the world around them.

    The purpose of this study is to determine the ability of 3-month old full-term and preterm infants to: (1) learn the contingency between leg action and mobile activation, and (2) demonstrate a greater amount kicking and an increase of selective leg movement when leg actions are reinforced with mobile activation.  Each infant participates in 2 sessions of mobile reinforcement on consecutive days.  Day 1 consists of a 2-min non-reinforcement condition (spontaneous kicking) followed by a 6-min reinforcement condition (the infant mobile rotated and played music).  Day 2 consists of a 2-minute non-reinforcement condition, 6-minute reinforcement condition, and 2-minute non-reinforcement condition. 

     Collaborators

    • Barbara Sargent, PhD, PT, PCS, Assistant Professor of Clinical Physical Therapy, USC
    • Hendrik Reimann, Ruhr University, Germany
    • Masayoshi Kubo, ScD, PT, Department of Physical Therapy, Niigata University of Health and Welfare, Niigata, Japan

     

    Modeling the Infant Exploratory Process

    A critical issue in the study of infant development is to identify the processes by which task-specific action emerges from spontaneous movement. It has been proposed that infants learn to tune their spontaneous movements to generate task-specific action through reward learning, which is characterized by exploration preceding learning, and accompanied by task specific reduction in variability. However, the contribution of exploration to the early learning of task-specific action has little empirical evidence during infancy. We are computationally modeling our infant kicking data to predict the movements associated with learning the task. The difference between the model and the task-specific movement trajectory data from each infant is considered to be the exploration related variance. Our findings will provide the first quantification of the contribution of exploration to the early learning of task-specific leg action of infants. 

     Collaborators

    • Nicolas Schweighofer, PhD, Associate Professor, Division of Biokinesiology & Physical Therapy; Department of Neuroscience; Department of Computer Science, USC
    • Barbara Sargent, PhD, PT, PCS, Assistant Professor of Clinical Physical Therapy, USC

     

    The Emergence of Movement Dynamics in Selective Infant Leg Action

    The purpose of this study is to investigate the biomechanical factors that contribute to the early emergence of selective leg action.  We define selective leg action as the coordination between intralimb leg joints that allows increased degrees of freedom among joints.  We compare dynamics between a 2D and 3D computation of torques and the dynamics that emerge longitudinally as infants mature in the first months of life.

     Collaborators

    • Barbara Sargent, PhD, PT, PCS, Assistant Professor of Clinical Physical Therapy, USC
    • Hendrik Reimann, Ruhr University, Germany
    • Masayoshi Kubo, ScD, PT, Department of Physical Therapy, Niigata University of Health and Welfare, Niigata, Japan

     

    Early Intervention for Infants with Brachial Plexus Injury

    We are initiating innovative intervention studies aimed at improving long-term upper limb function in infants who have sustained brachial plexus injury.Incomplete neural recovery often contributes to the development of maladaptive movement patterns and shoulder deformity. Targeted rehabilitation programs may help to prevent long-term disability in this vulnerable group. This line of research follows up on work by Dr. Susan Duff examining recovery patterns and prehensile skill development in this population.  

     Collaborators

    • Susan Duff,PT, OTR/L, EdD, CHT, NIH T32 Post-doctoral Fellow in Training inRehabilitation Efficacy & Effectiveness Trials, USC
    • Jason Kutch, PhD, Assistant Professor, Division of Biokinesiology & Physical Therapy, USC
    • Barbara Sargent, PhD, PT, PCS Assistant Professor, Division of Biokinesiology & Physical Therapy, USC