Emergence of arm reaching behavior and lateralization of motor control in infancy

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Project Summary It is crucial to understand how infants learn to progress from spontaneous movements into goal-directed, refined motor skills. Infant learning is the focus of early intervention programs, and the need for effective early intervention is great. Until we understand the mechanisms of development and what promotes or inhibits successful infant learning, we cannot design optimal early intervention. Our specific objective is to longitudinally study infant experience (infant and environmental factors) and underlying neural substrates (electroencephalography (EEG)) as infants learn arm reaching, an early, foundational motor skill. Current theories suggest that infants learn through a repeated perception-action process and that experiencing error is the key mechanism for successful infant learning. Thus, Aim 1 will measure error rate longitudinally across the emergence and refinement of reaching. In Aim 1 we will determine the relationship between error rate and the development of reaching skill. We hypothesize that infants will demonstrate a high error rate (errors/attempts) near reaching onset that decreases as they refine the skill, supporting the idea that making errors is a key experience in order for learning to occur. Aim 2 will focus on individual infant and environmental factors that predict age of onset of reaching. In Aim 2 we will identify infant and environmental factors related to the age of reaching onset. Infant factors are motor experience (amount and type (unilateral or bilateral) of daily arm movement experience) and cognitive development status. Environmental factors are level of maternal education, quality of caregiver-infant interactions, nutrition, and sleep. We hypothesize that these factors are related to the age at which infants are observed to begin to reach, and we will determine the strength of the associations and characteristics of infants reaching at different ages. The results will identify targets for intervention that are most likely to be successful. Aim 3 will use EEG to determine how brain function changes as reaching is refined from an unstable skill to a successful, lateralized (typically right arm preference) movement. Using EEG will allow us to collect data in the home, both resting state and during arm movements. In Aim 3 we will identify patterns of concurrent brain activity that differentiate between spontaneous arm movements, early reaching attempts, and skilled reaches in infants with typical development. Based on our pilot data, we hypothesize that frontal-parietal connectivity increases, interhemispheric connectivity decreases, and sources of EEG activity shift from bilateral to unilateral as reaches become more goal directed, successful, and lateralized. Aims 1–3 focus on infants with typical development; exploratory Aim 4 contrasts our findings with a population likely to show impairment in learning to reach: infants at high risk for cerebral palsy. In exploratory Aim 4 we will describe patterns of concurrent brain activity during spontaneous arm movements, early reaching attempts, and skilled reaches in infants at high risk for cerebral palsy. Our results will determine the most relevant factors related to an infant’s ability to refine his brain function and neuromotor control as he learns to reach.