THE COGNITIVE NEUROSCIENCE OF COMPREHENSION

Tufts University Medford, Medford MA

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Abstract

DESCRIPTION: The aim of the proposed research is to continue our study of comprehension processes in the human brain. The primary approach will entail the recording of event-related potentials (ERPs) from 64 scalp electrodes while subjects engage in a series of experiments designed to tap specific information processes associated with language comprehension. In addition we will begin to use event-related functional magnetic resonance imaging (er-fMRI) methodology in a limited number of studies where the potential for combining techniques offers the greatest promise. Our research has three related foci. The first is to use ERPs, and now er-fMRI. to test and elaborate on current cognitive theories of online language comprehension. We propose that this cognitive neuroscience approach will help better tie cognitive theories of comprehension to theories of brain function. The second focus is on improving our understanding of the relationship between ERP measures of comprehension and the cognitive/linguistic processes they are hypothesized to reflect. The final focus is on combining ERPs with er-fMRI in a select subset of 3 parallel experiments which will use the same paradigms in the same subjects. The data will be quantitatively combined to produce temporo-spatial maps which will provide greater insights into the time-course of the functional neuroanatomy underlying language comprehension. The proposed experiments will examine linguistic processes across three levels of comprehension. 1. Word Level Studies. In four experiments we propose to investigate hypotheses of the functional significance of the N400 by recording ERPs and er-fMRI data to words presented in isolation. 2. Sentence Level Studies. In five experiments we will test hypotheses about processes involved in recognizing words in natural spoken sentences and the functional significance of three ERP components thought to reflect semantic/pragmatic and syntactic processes associated with comprehension. 3. Discourse Level Studies. In a series of ten experiments we will look at four devices used in comprehending pieces of text larger than single sentences. We will test theories of how comprehenders attach pronouns to their referents, make inferences between sentences, understand metaphors and use coherence within and between sentences in text. While the proposed experiments will be performed in normal young adult subjects, one goal of this research is to provide a framework for studying cognitive and language processes in language impaired adults and children.