WORKING MEMORY AND PHONOLOGICAL REPRESENTATION

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Language is fundamentally important for many aspects of our day- to-day functioning. A central aspect of language concerns the translation of environmental stimuli into internal phonological representations, with new word learning partially requiring the encoding of novel phonological representations into long-term memory. The proposed experiments will use event-related functional magnetic resonance imaging to examine interactions between working memory, phonological representation, and memory encoding. These studies will test hypotheses regarding the role of the phonological loop-a working memory system-in the representation and encoding of novel phonological forms. Moreover, These studies will determine which of the sub- components of the phonological loop-the articulatory mechanism, the phonological representation and memory formation. The first specific aim is to test whether brain regions subserving the phonological loop-left inferior prefrontal (LIPC) and left perisylvian (LPSC) cortices-differentially support the generation of novel phonological representations. Experiment 1 will address this aim by examining brain activation associated with the processing of stimuli that parametrically vary in phonological familiarity (from high, to moderate, to low). The second specific aim is to test the hypotheses that the phonological loop differentially contributes to the formation of long-term memory for novel phonological representations, and that these contributions specifically reflect the operations of the articulatory sub-component of the phonological loop. Experiment 2 will address this aim by examining whether the magnitude of activation in LIPC and LPSC during the processing of phonological forms predicts whether the forms will be later remembered or forgotten, and whether these subsequent memory effects are greater as the novelty of the phonological forms increases. Experiment 3 will further address this aim by combining a word- length manipulation, designed to specifically target the articulatory sub-component, with a subsequent memory paradigm to explore whether phonological-loop contributions to memory encoding differentially reflect the operation of the articulatory mechanism. Previous research has indicated that working memory operations for language function, with the phonological loop perhaps contributing to novel word learning. The proposed studies will provide new information about the anatomic and cognitive architectures supporting phonological language operations and the relation of these operations to long-term learning. As such, they will provide a foundation for subsequent studies with language impaired individuals, and should contribute knowledge towards further refinement of rehabilitation efforts.