Event-related brain potentials (ERPs) will be recorded from 4 age groups, young children (ages 5-7), children (9- 11), adolescents (14-16) and young adults using experiments designed to assess the development of direct (i.e., explicit) and indirect (i.e., implicit) memory. One goal of the proposal is to study direct memory performance using tasks for which performance has been demonstrated to depend upon the medial temporal (recognition memory) and frontal (memory for source) lobes. The neuropsychological and neuroanatomic data that do exist suggest long maturational courses for structures presumed to subserve these explicit memory functions, whereas the putative sensory and neocortical association areas that subserve implicit memory function do not appear to undergo such long developmental trajectories. These data lead to the prediction that implicit memory function should be in place in the youngest subjects under investigation while explicit memory function is still developing. Thus, in the first phase of this proposal, repetition priming (indirect memory) of pictorial stimuli will be followed by yes/no recognition (direct) memory, in which memory for source will be assessed. Pictures are used here because they are easily adapted for source judgements. ERP and behavioral evidence suggests that the left and right hemispheres are differentially engaged by environmental sounds and their verbal referents during cross-form semantic priming tasks. However, little is known about the developmental dynamics or of the maturational aspects of how the cerebral hemispheres interact in retrieving these same stimuli during delayed recognition memory tasks. In the second phase, therefore, word-sound and sound-word priming of environmental sounds and their verbal referents will be followed by recognition memory for these same stimuli. Words and sounds are used here because they are two different auditory representations of the same concept. In the first phase, ERP and reaction time (RT) repetition effects will be compared between direct and indirect memory tasks from a developmental vantage point. In the second, ERP and RT cross-form priming effects will be compared between the priming series and the delayed recognition test also from a developmental viewpoint. It is expected that the repetition and cross-form priming effects will reflect the magnitude of priming during the on-line and delayed memory tasks, and may change systematically across the age range studied. ERPs will be recorded from 30 scalp sites to enable current source density analyses, in order to better resolve scalp distributions to determine whether they, and, by implication, their intracranial generators, show age-related change. The data will be relevant to the developmental course of direct and indirect memory, semantic processing, and their physiological underpinnings.
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