Phonological working memory is the mechanism by which language-relevant sounds are maintained in short- term memory. Phonological working memory is a core construct in cognitive, developmental, and clinical neuropsychology, as well as speech-language pathology, and plays an important role in language acquisition, vocabulary development, learning to read, and language comprehension. Phonological working memory deficits are characteristic of numerous developmental disorders of communication, including developmental language disorder (specific language impairment), developmental reading disorder (dyslexia), autism, and Down syndrome. Even in adulthood, phonological working memory deficits remain deleterious to the language abilities and psychosocial functioning of individuals with developmental language disorders. However, there has been no prior attempt to investigate the brain bases of phonological working memory using tasks analogous to clinically sensitive measures such as nonword repetition. Moreover, virtually nothing is known about how phonological working memory impairments in individuals with developmental language disorders arise from differences in neurophysiology or neuroanatomy. Correspondingly, the first goal of this project is to deter- mine the normative neural systems recruited by clinical phonological working memory assessments in the brains of adults with typical language abilities (Aim 1). Critically, we will ascertain whether the brain bases of phonological working memory are related to neural systems underlying domain-specific linguistic processing or domain-general cognitive abilities. This will help reconcile two competing theories about how phonological working memory works in the brain, as well as inform the clinical interpretation of nonword repetition tests. The second goal of this project is to examine phonological working memory in the brains of adults with persistent developmental language disorder, including how they differ from controls and how individual variability in neural responses is related to behavioral differences in language ability (Aim 2). Finally, we will collect pilot data from a smaller sample of children with developmental language disorder in support of future research aimed at understanding brain differences in children with developmental language disorders.
Phonological working memory - an important property of the brain that allows individuals to store and maintain the sounds of speech during language processing - is impaired in a variety of developmental disorders of language, reading, and communication. However, little is known about what parts of the brain are responsible for phonological working memory, whether these brain areas also support other linguistic or cognitive functions, and how these brain areas may be dysfunctional in children and adults with developmental communication disorders. Understanding the brain bases of typical and impaired phonological working memory will help clinicians implement more effective strategies for assessment and remediation of neurogenic developmental communication disorders.