Kelly A. Snyder - US grants

DESCRIPTION (provided by applicant): Preferential looking paradigms have been used for almost 50 years to study detection and discrimination of stimuli, categorization, memory, concept formation, and individual differences in infant cognition. Yet, relatively little is known about the nature of the representations which mediate novelty preferences. The general aim of this research is to investigate the neural correlates of novelty preferences during the first year of life in order to elucidate the nature of the representation reflected in an infant's differential attention to a novel stimulus. To accomplish this goal, two experiments are proposed. Experiment 1 will employ a cross-sectional design in order to allow the evaluation of differences in infant electroencephalogram (EEG) and event-related potentials (ERPs) which predict novelty preferences across the first year of life. One goal of this research is to evaluate infant novelty preferences against an adult model of dissociable memory systems. In order to investigate this, the effect of retention interval on infant memory will be assessed by two different tasks: preferential looking and priming. ERPs will be recorded while infants participate in these tasks to assess the extent to which different neural circuits may dissociate performance on the tasks, whether there is a difference in the pattern of brain activity which predicts immediate vs delayed recognition memory, and whether there is a difference in the pattern of brain activity during familiarization across the first year of life. Experiment 2 will investigate the effect of experience on novelty preferences in infancy. This will be accomplished b manipulating infants' experience with a particular class of stimuli, and testing infants before and after this experience. The goal of this study are to assess whether experience with a particular class of stimuli effects performance on preferential looking task whether this experience effects brain re-organization of memory systems with respect to the stimuli, and whether such reorganization, if it is found, persists over time even when the stimuli are removed from the environment.

Description (provided by applicant): Preferential-looking paradigms rely on an infant's inherent "preference" for viewing novel stimuli (i.e., novelty preferences) to provide evidence for memory or discrimination. Our long-term goal is to elucidate the neural mechanisms underlying performance on preferential-looking tasks in order to advance our knowledge about the functional neurobiology and development of visual attention and memory. Such knowledge has important implications for understanding cognitive development in general, and will ultimately help to inform our understanding of how disruptions in the development of these systems may give rise to developmental disorders. The specific hypothesis behind the proposed research is that preferential-looking primarily reflects the incidental encoding of the visual scene into a perceptual store vs. the recollection or recognition of information. The specific aims of this proposal are to: 1. Investigate whether novelty and familiarity preferences are associated with the same or different cognitive processes. The processes underlying novelty and familiarity preferences will be investigated by examining he relation between preferential-looking in the visual-paired comparison (VPC) and subsequent processing of the familiar stimulus via ERPs. Differences in the topography of ERP components can be inferred to reflect differences in the underlying neural circuits, and hence cognitive processes. 2. Dissociate processes related to recognition vs. priming. This will be accomplished by examining the relation between novelty preferences in the VPC and subsequent ERP differences during the processing of familiar and novel stimuli. 3. Dissociate processes related to familiarity vs. recency. This will be accomplished by investigating the effects of repetition of novel and familiar stimuli on ERPs in 6-month olds, focusing in particular on components that have been related to performance on preferential-looking tasks in previous work.

DESCRIPTION (provided by applicant): The overall goal of the proposed research is to investigate the relative contributions of familiarity and recollection to the development of visual recognition memory in infants as assessed by the visual-paired comparison (VPC). Despite the extent to which the VPC has been used to study memory in infants, a key distinction has been overlooked in interpreting results of this research: that between conscious recollection and assessments of familiarity. Recollection involves the retrieval of qualitative information about the context in which an item was previously encountered, and is thought to depend critically on the hippocampus. Familiarity, on the other hand, involves the assessment of global similarities between study and test items that appears to be mediated by perirhinal cortex and high-level visual association areas. The extent to which recollection and familiarity contribute to visual recognition memory in infants is a key focus of the present research, and is critical to our understanding of both memory development and brain development in infants. The hypotheses being tested are that (a) familiarity contributes to infant visual recognition memory earlier in development than recollection, and (b) recollection does not emerge until sometime during the second year of life. To test these hypotheses, we will examine the effects of manipulations known to dissociate recollection and familiarity in adults on infants'performance in the VPC. The specific aims of this application are to: (1) Examine the contribution of recollection to infant visual recognition memory. Separate groups of 9-, 12-, 18-, and 24-month-old infants will be tested in two versions of the VPC: one in which the orientation of the familiar object stays the same from familiarization to test (same- orientation condition), and another in which a mirror-inversion of the familiar object is presented at test (mirror-reflection condition). If recollection contributes to infants'performance in the VPC, then study-test changes in reflection should disrupt infants'recognition memory in the VPC. (2) Examine the contribution of familiarity to infant visual recognition memory. Separate groups of 9-, 12-, 18-, and 24-month-old infants will be tested in two versions of the VPC: one in which each test trial is preceded by a masked presentation of the familiar object (same-prime condition), and another in which test trials are preceded by a masked presentation of an unfamiliar object (different-prime condition). If familiarity contributes to infants'recognition memory in the VPC, then brief pre-test presentations of the familiar object should facilitate infants'performance in the VPC. The work proposed here is the first step in a long-term plan to systematically examine the electrophysiological correlates of recollection and familiarity in infants. PUBLIC HEALTH RELEVANCE: The outcome of the proposed research will provide important new information about memory development in typically developing infants. This knowledge could dramatically change the way we think about infant cognition, and will ultimately help us understand how disruptions in the development of brain systems involved in learning and memory may give rise to developmental disorders.