Reflections on the Cognitive Neuroscience of Language

Abstract

This chapter provides some brief reflections on how the past 20 years of study of the cognitive neuroscience of language have changed the way in which we think about the nature of human language and the functional role of the two hemispheres in processing language. Two theoretical claims about the modularity of language are considered: (1) that language is modular in a narrow sense, that is, its various parts or components are functionally and neurally autonomous, and (2) that language is modular in a broad sense, that is, it is functionally and neurally separate from other cognitive functions. It is argued that the evidence to date challenges both claims of a theory of modularity. The functional properties of language, that is, speech, lexical processing, and syntactic processing, appear not to be focally represented in one area of the brain; rather, each recruits a broadly distributed neural network or processing stream. Moreover, certain areas of the brain that have been associated with language processing appear to be recruited across other cognitive domains, suggesting that while language may be functionally special, it draws on at least some neural mechanisms and computational properties shared across other cognitive domains. Finally, although it is generally assumed that the left hemisphere is dominant for language, functional neuroimaging studies often show activation in right hemisphere areas that are homologous to areas in the left hemisphere. These findings raise new questions about the potential role of the right hemisphere in language processing.