Development and plasticity of the neural network for speech motor control

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Human speech production is a deceptively simple motor skill that the majority of people take for granted. In actuality, speech requires the complex sequencing of movements among the respiratory, laryngeal, pharyngeal and oromotor subsystems with millisecond level precision. Despite the unique role that speech plays in human interaction, and the debilitating impact of its disruption, little is known about the neural mechanisms underlying speech-motor learning and its development.******Over the course of my doctoral and post-doctoral training I investigated the neural mechanisms of auditory feedback in online speech-motor control. I documented the importance of the neural inhibitory effect of speech-motor efference copy on auditory feedback during accurate speech production in healthy adults and, for the first time, in children (Beal et al., 2010, 2011, 2013). I also discovered that adult speech-motor learning is associated with changes in neural activity in both networks typically associated with general motor learning (basal ganglia and pre-supplementary motor area) and auditory-motor feedback control for speech (ventral premotor, posterior superior temporal gyrus; Beal et al., in preparation; Segawa et al., online ahead of print). ******The results of my previous studies led me to question how speech-motor learning develops in childhood and its critically important role for establishing the stable neuro-motor programs necessary for accurate speech-motor control over one's lifespan.******My proposed research program will use behavioral and multi-modal quantitative magnetic resonance imaging to investigate the functional and structural development of the neural network for speech motor sequence learning in children aged 4-12. The specific aims are to:******1. Determine the developmental trajectory of neuro-motor program stability for speech.******2. Determine the developmental trajectory for auditory-motor learning of speech sounds.******3. Differentiate the contributions of the cortico-striatal (general motor) and cortico-cortical (auditory motor) neural networks to speech-motor learning in childhood.******This research will reveal how the brain develops and integrates auditory-motor information for establishing neuro-motor programs for speech production. It will enrich our understanding of how the functional and structural neural pathways for speech processing are acquired over the course of learning and development.**