This project continues to study premature and brain injured neonates, hypothesizing (a) that these risk conditions differentially reduce the ability to modulate arousal and attention processes, and (b) that the pattern of disruption in arousal/attention modulation predicts both degree of early brain injury and later percentual cognitive and motivational development. We have developed and refined a measure of neonatal behavior using the visual preference technique that shows systematic differences in preference functions with controlled manipulations of arousal due to changes in internal as well as external sources of stimulation. We have demonstrated that: (a) high-risk and preterm infants, as to normal term infants, show a general shift in looking preference with arousal manipulations; but that (b) the more severe the brain injury, the less the shift in looking preferences toward higher frequencies when less aroused. The present proposal will enable us to establish how CNS pathology, acting through poor arousal/attention modulation in the neonate, can form the substrate on which later behavior develops and can be expressed in diverse circumstances related to higher- level cognitive attainment. Infants (n=288) stratified into 8 groups related to brain injury will be studied from birth to 19 months at 3 month intervals. We have designed studies that will provide converging information from measures of arousal modulated visual recognition memory, cortisol reactivity to different stressors, and vagally mediated control over heart rate. We predict that arousal manipulations will modulate responding across measures, but that degree of response modulation will be differentially affected by degree and type of CNS compromise. Prior to hospital discharge, and at 1 and 4 months, visual recognition memory will interact with arousal level in a manner analogous to the visual preference task such that the magnitude of difference between preferences for novelty in different arousal conditions will be proportional to CNS insult, with arousal less influential the older and healthier the infant. As the infant matures, more challenging tasks will be needed to differentiate brain injury; for example, those involving intersensory (auditory-visual) integration may become better discriminators. We hypothesize that measures of focused attention, distractibility, irritability, goal-directed behavior, and exploratory behavior at later ages will correlate to lack of modulation of early attention.
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