There are lifelong challenges faced by adults with (Specific) Language Impairment (LI), a common learning disability that affects 7% of the US population (Tomblin et al., 1997). Despite documented difficulties in educational attainment, vocational outcome, and legal standing for adults with LI (Bryan et al., 2007; Conti- Ramsden et al.,2009; Johnson et al.,2010), research on adults with LI have been all but been ignored in the literature. As a result, we know very little about the barriers to educational and vocational attainment faced by young adults with LI, such as the potential impairment in learning and memory. Our recent work has found that, following perceptual training on new (nonnative) acoustic-phonetic information, sleep facilitates improved perceptual ability in adults with typical language, but not in adults with a history of LI. How memory consolidation in perceptual learning relates to broader memory encoding in LI is not yet clear. To this end, we aim to establish how performance on these tasks inform relative strengths and weaknesses in well-understood memory systems: specifically, procedural and declarative memory. Furthermore, we must understand the neural mechanism underlying this observed behavioral failure in offline consolidation. Therefore, the research outlined in this proposal seeks to determine the association between perceptual learning and declarative and procedural memory, and to identify the neural mechanism underlying the behavioral phenomenon of consolidation failure in LI.
Our aims will be addressed by combining behavioral data in established procedural and declarative learning tasks with our perceptual learning task. We will also extend our behavioral protocol on perceptual learning to investigate neural processing of trained speech sounds before and after sleep using functional magnetic resonance imaging (fMRI) techniques. The knowledge to be gained through this research will inform the time course of memory consolidation in individuals with LI, and inform the cognitive substrates of speech sound acquisition in adulthood more broadly. Furthermore, by defining a potentially critical obstacle to achievement, this knowledge may contribute to improving remediation outcomes for young adults with this common developmental disability. The knowledge to be gained through the proposed project will contribute to four areas of research: (Specific) Language Impairment, speech perception, second language learning, and memory consolidation. .
(Specific) language impairment (LI) is a common learning disability that affects approximately 7% of the population in the U.S., with persistent deficits in speech perception that impose significant functional challenges into adulthood. The proposed research will contribute to our knowledge of the interplay between memory consolidation in perceptual learning in typical adults and adults with a history of LI. An understanding of how memory encoding affect speech perception can inform the appropriate remediation of deficit, and constrain theory regarding the speech perception deficits observed in this common learning disability.
