Language Processing and Hippocampal Declarative Memory
R01 NIH DC011755; 4/2012 – 3/2019
This research program explores the novel hypothesis that many of the processes by which we produce and understand language also place high demands on and receive contributions from the hippocampal declarative memory system. This system is uniquely positioned to access and integrate discourse, contextual and experiential information that the language processing system relies on to resolve ambiguity and create meaning. Recent provocative work extends the traditional view of declarative memory as contributing exclusively to long-term memory, to include a critical role in the generation and use of on-line representations, created during ongoing and online information processing to support behavioral performance in the moment. The proposed studies build upon a set of exciting preliminary findings revealing language deficits at low levels of language processing (i.e., within a single noun phrase), and in the absence of any explicit demands on memory (e.g., no delays; when all the stimuli remain in view) in patients with severe and selective declarative memory impairment. Our studies are built around investigating three key areas of language processing where proposals of the memory determinants are central, but untested: Aim 1: To investigate the demands of interactive dialogue on declarative memory; Aim 2: To investigate the demands of referential processing on declarative memory; Aim 3: To investigate the demands of accommodation of talker variability on declarative memory. Our experimental approach capitalizes on a compelling opportunity to combine the study of patients with hippocampal amnesia with eye tracking and behavioral measures to examine the necessity of a form of memory in meeting the demands of language. We will therefore be uniquely able to determine the contributions of hippocampus and declarative memory to language processing and use across multiple levels of language production and comprehension providing crucial tests of hypothesized roles for memory in language use. Because language disruptions are common in many neurological and psychiatric conditions where impairments in declarative memory are also prominent, including stroke, traumatic brain injury, Alzheimer’s disease, and schizophrenia, our efforts to characterize the observed deficits and link them to underlying mechanisms are necessary for understanding the broader neural network and cognitive processes that support language use and for developing more sensitive assessments and effective interventions. This proposal, and the findings generated, offers unparalleled insights and advancements for theories of language processing, clinical service delivery to individuals with concomitant disorders of language and memory, and understanding the organization and operation of language in the brain.
Duff, M.C., & Brown-Schmidt, S. (2012). The hippocampus and the flexible use and processing of language. Frontiers in Human Neuroscience, 6. doi: 10.3389/fnhum.2012.00069.
Kurczek, J., Brown-Schmidt, S., & Duff, M.C. (2013). Hippocampal contributions to language: Evidence of referential processing deficits in amnesia. Journal of Experimental Psychology: General, 142 (4), 1346-1354.
Trude, A., Duff, M.C., & Brown-Schmidt, S. (2014). Talker-specific learning in amnesia: Insight into mechanisms of adaptive speech perception. Cortex, 54, 117-123.
Brown-Schmidt, S., & Duff, M.C. (2016). Memory and common ground processes in language use. Topics in Cognitive Science, 8(4), 722-736.
Duff, M.C., & Brown-Schmidt, S. (2017). Hippocampal contributions to language use and processing. In Hannula, D. & Duff, M.C. (Eds.). The hippocampus from cells to systems: Structure, connectivity, and functional contributions to memory and flexible cognition. pp. 503-536. Springer International Publishing.
Yoon, S.O., Duff, M.C., Brown-Schmidt, S. (2017). Learning and using knowledge about what other people do and don’t know despite amnesia. Cortex, 94, 164-175.
Covington, N., Brown-Schmidt, S., & Duff, M.C. (2018). The necessity of the hippocampus for statistical learning. Journal of Cognitive Neuroscience, 30(5), 680-697.
Ryskin, R., Qi, Z., Covington, N., Duff, M.C.,& Brown-Schmidt, S. (2018). Knowledge and learning of verb bias in amnesia. Brain and Language, 180-182, 62-83.