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Key Words sentence processing, discourse processing, psycholinguistics,
phonological processing, fMRI, PET
Abstract The 1990s were dubbed the "Decade of the Brain." During this time there was a marked increase in the amount of neuroimaging work observing how the brain accomplishes many tasks, including the processing of language. In this chapter we review the past 15 years of neuroimaging research on language production and comprehension. The findings of these studies indicate that the processing involved in language use occurs in diffuse brain regions. These regions include Broca's and Wernicke's areas, primary auditory and visual cortex, and frontal regions in the left hemisphere, as well as in the right hemisphere homologues to these regions. We conclude the chapter by discussing the future of neuroimaging research into language production and comprehension.
CONTENTS
INTRODUCTION
For cognitive neuroscientists the Holy Grail of research is to ascertain how the brain accomplishes its work. Throughout the history of psycholinguistics this goal could only be had through indirect means: Hints about the brain regions involved in language production and comprehension were provided by the vast and growing neuropsychological literature, documenting the task performance of patients who had suffered lesions to particular brain regions (e.g., Zurif & Swinney 1994, Obler & Gjerlow 1999).
In the decades following World War II, however, technology was developed that allowed researchers to exploit the changes in blood flow that accompany neural activity to study the brain at work. Use of this neuroimaging technology was in its infancy in 1994, when the first Handbook of Psycholinguistics appeared in print. Whereas a few pioneering neuroimaging studies had been performed incorporating language tasks (e.g., Petersen et al. 1988, 1989, 1990), research of this sort was scant. Indeed, there is hardly a reference to neuroimaging work in the pages of the Handbook, though there were chapters on neuropsychology. In the decade since then the situation has changed. There now exists a small but growing literature exploring the means by which the working brain of healthy individuals processes language, covering most of the major areas of psycholinguistics.
In this chapter we review the past 15 years of neuroimaging work on language processing. We take the term "neuroimaging" to refer to research using functional magnetic resonance imaging (fMRI) and positron emissions tomography...