Neural Mechanisms of Selective Auditory Attention in Lower Socioeconomic Status Preschoolers: Individual Differences, Genetic Influences, and Gene x Intervention Interactions
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Selective attention refers to the ability to enhance the processing of relevant stimuli, while suppressing the processing of irrelevant distractors. The neural mechanisms of selective attention are vulnerable in children from lower socioeconomic status families, yet these neural mechanisms can also be enhanced with evidence-based, targeted training. The series of studies presented in this dissertation investigated the individual differences in development and neuroplasticity of selective auditory attention in association with nonverbal cognitive abilities, in relation to genetic influences, and in the context of gene x intervention interactions. To this end, a multi-method approach was adopted, combining several methodologies such as event-related potentials (ERPs), behavioral measures, molecular genetics, and a randomized, controlled intervention design. In the first study, individual differences in neural mechanisms of selective auditory attention were studied, in association with nonverbal cognitive abilities. More robust ERP selective attention effects were associated with superior nonverbal IQ performance. These results indicated a noteworthy relationship between neural mechanisms of selective attention and nonverbal IQ performance in lower socioeconomic status (SES) preschoolers. In the second study, the relationship between 5-HTTLPR polymorphism and neural mechanisms of selective auditory attention was assessed. ERPs of selective attention effect were larger in children who carried at least one short allele of 5-HTTLPR, in comparison to long-homozygotes. These results associated being homozygous for the long allele with weaker neural mechanisms of selective attention in lower SES children. In the third study, these genetic influences were investigated in the context of an effective family-based training program previously shown to improve neural mechanisms of selective attention in lower SES preschoolers. The long-homozygote children, who initially displayed more attenuated ERPs of selective auditory attention than their short-carrier peers, showed robust ERPs of selective attention at posttest, but only if they were randomly assigned to the training program. These findings demonstrated that an effective family-based training could moderate the genetic influences of 5-HTTLPR on the neural mechanisms of selective attention. Taken together, the studies presented in this dissertation contribute to elucidating individual differences in development and neuroplasticity of selective auditory attention in lower SES preschoolers. This dissertation includes unpublished co-authored material.