This project investigates the organization of arousal and attention in high-risk neonates suspected of suffering brain insult. Since brain insult is more likely to compromise subcortical and brainstem areas the earlier in development it occurs, and since these regions are more likely to be involved in arousal and attention processes in neonates, we hypothesize the earlier the prematurity when hemorrhage occurs and the more severe the hemorrhage, the less likely will be the ability to change attention as arousal changes. Degree of prematurity should not affect this interaction without corresponding brain insult. Infants will be tested near NICU discharge to establish their visual preferences along a temporal frequency dimension (1, 2, 4, 8 Hz). Preference functions will be obtained by observing the duration of fixation to each member of a pair of simultaneously presented stimuli with all combinations of stimuli balanced. The linear preference function across stimuli, found when a healthy neonate is fed and swaddled, is reversed if the infant is tested before feeding and unswaddled or tested after exposure to prior stimulation. Infants will be divided into 8 groups of 12 (Total N = 96) depending on: (1) the degree of prematurity evidenced by BW and EGA, and (2) the severity of hemorrhage evidenced by ultrasonography and brainstem auditory evoked responses. The normal interaction between arousal conditions in the slopes of the preference functions should be reduced by brain insult, and the more so the earlier the injury occurs in development. The course of recovery as estimated by the reduction in abnormal neurological and vital signs over the course of NICU stay, and the characteristics of the infants neurobehavioral and motor functions will be measured at discharge to obtain additional evidence as to the degree of severity of brain insult and as an alternative, but secondary estimate of resolution of insult. Contrasts will be conducted using these measures to analyze how they are affected by arousal and attention.
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