Donna Thal - US grants

My major career objective is to establish and maintain an active inter- disciplinary research program concerned with issues in cognitive, linguistic, and neurological development. My research has three primary aims: 1) to describe in detail developmental trajectories of normal and abnormal language development from pre-linguistic intentional com- munication through the establishment of complex syntax, 2) to identify early predictors of risk for language disorders and learning dis- abilities, and 3) to describe the relationships between the development of language and nonlinguistic cognition and the development of the neural mechanisms that support them. l am already engaged in research dedicated to the first two aims, and l have done some preliminary work in the third area. The coursework, clinical, and laboratory rotations neurology, neurosciences, and neural network modeling proposed in this RCDA are to provide needed fluency in those fields so that I can formulate well constructed hypotheses and research designs founded solidly in the neurosciences as well as developmental psycholinguistics. The training that I receive through the RCDA will help the planned departmental transition to stronger training in neurologic foundations of communicative disorders, and establish the kind of interdisciplinary training for our students that will be essential to adequate training of speech-language pathologists in the next century. I have office and laboratory space configured specifically for my research needs, and I will be able to retain adequate space should I receive the RCDA. The goals of funded research project (Project 1 of P01# DC01289) are to achieve an understanding of the linguistic and non-linguistic factors that are associated with persistent deficits or successful recovery from initial language delay in children in the bottom tenth percentile for expressive vocabulary at 18 to 24 months of age, to coordinate the behavioral profiles with electrophysiological studies of the same children (Project 5), to determine whether and to what extent changes in linguistic and non-linguistic ability in late talkers can be linked to specific changes in brain organization for language, and to compare results from late-talkers with the cross-domain profiles and developmental trajectories displayed by children with focal brain injury (Project 2), Down syndrome and Williams syndrome (Project 3), and prenatal exposure to cocaine (Project 4).

The broad goal of this project, Origins of Communication Disorders in Late Talkers, is to achieve an understanding of the linguistic and non- linguistic factors that are associated with persistent deficits or successful recovery from initial language delay in a population of children who are in the bottom tenth percentile for expressive vocabulary between 18 and 24 months of age. Followup studies in our laboratory and at other research sites demonstrate that approximately 40% of these children qualify for a diagnosis of specific language impairment by 3 - 4 years of age. To uncover the factors associated with early and persistent language delay, we have designed our measures around two periods of development: (1) the earliest stages of language acquisition (18 - 36 months), when accurate determination of language impairment is still difficult to make, and (2) preschool to first grade (3 - 6 years), when diagnosis with standardized tests is possible. Based on pilot studies with a small sample of late talkers, we have developed a series of specific hypotheses concerning (1) intralinguistic factors (e.g. receptive language profiles) that distinguish between "late bloomers" and the truly language impaired during the "preclinical" stage(i.e. 18 - 24 months), and (2) extralinguistic factors (e.g. aspects of symbolic gesture) that also differentiate between these two groups, increasing the validity and reliability of early diagnosis. In addition, we will investigate the shape and nature of recovery from delay in those children who do recover, including (3) cognitive infrastructures, i.e. non- linguistic skills that must be in place before successful recovery can begin, (4) alternative modes of communication (gestural, vocal, facial) that are used by "late bloomers" during their period of delay, compared with the non-linguistic alternatives displayed by children with persistent deficits. For those children who do show apparent recovery according to standardized tests, the 3 - 6 year battery contains a series of more subtle linguistic measures that can be used to determine (5) whether or not the "late bloomers" continue to display subtle deficits in oral language ability that may affect their performance in the school system. Finally, (6) the behavioral profiles obtained in this project will be coordinated with electrophysiological studies of the same children (see Project 5), to determine whether and to what extent changes in linguistic and non-linguistic ability in late talkers can be linked to specific changes in brain organization for language. Results for both groups of late talkers will be compared with the cross-domain profiles and developmental trajectories displayed by other groups under study within the Program Project. In addition to their clinical/diagnostic value, results of all these studies are relevant to fundamental questions about the nature of the language processor: Do the initial delays in language displayed by late talkers reflect temporary and/or persistent deficits in a "language module" that can be dissociated from other mental/neural systems? Or will we find that initial delays and/or recovery from delay are systematically associated with delay and/or recovery in certain non-linguistic domains (e.g. attention, cognition, affect) that are critical for normal language development?

DESCRIPTION (provided by applicant): We request funding for a new training program, Neurocognitive Approaches to Communication Disorders, that emphasizes the application of new technologies and new theoretical frameworks in neuroscience and cognitive science (e.g., behavioral studies of real-time language processing, fMRI studies of children with SLI, electrophysiological studies of language learning) to research that is directly related to clinical practice in communicative disorders. The program proposed here allows us to take advantage of the unique structure of the young SDSU/UCSD Joint Doctoral Program in Language and Communicative Disorders (JDP) to provide such training in an environment that integrates communicative disorders, cognitive sciences, neurosciences, psychology, and linguistics and make better use of the rich clinical resources available through the SDSU School of Speech, Language, and Hearing Sciences than has been possible to date. The training program will be headed by a committee of six senior scientists at SDSU whose research is focused on problems directly related to issues of characterization, assessment and interventions related to individuals with disorders of communication. We request funding for six predoctoral trainees who, through the requirements for the JDP, will specialize in adult language, child language, or multilingualism. Within those areas they will also develop expertise in at least one state-of-the-art research methodology (behavioral dynamics, neural imaging, neural modeling) while obtaining some exposure to all three methodologies through lab rotations, coursework, and program-wide activities such as seminars and journal clubs.