Three Conundrums of Language Lateralization

Abstract

The lateralization of language to the left hemisphere of the brain in most righthanded individuals is well established; however, this arrangement has no widely accepted theoretical explanation. The distribution of language across the cerebral hemispheres raises issues and contradictions that are difficult for any theory to accommodate. In this article, we review three puzzles about the lateralization of language: (1) the clinical literature reveals profound deficits in language only after left-hemisphere damage, but the brain imaging literature shows bilateral activation in most language tasks; (2) language is left-hemisphere dominant in most individuals yet deviation from this pattern does not result in language dysfunction; and (3) lateralization and handedness are related, but the factors that underlie this relation are unknown. We also briefly discuss evolutionary and genetic theories that have been advanced to explain lateralization. Three Conundrums of Language Lateralization The ability to communicate about our mental lives, to reflect on and learn from the past, and to pass on what we have learned to others is rooted in the human species’ use of language. The flexibility and creativity of the language system contributes to what has been referred to as ‘the unbounded quality of the human mind’ (Corballis 1991, p. v). Although other species communicate, none have developed a system with the flexible and complex structure of language. One of the most well-accepted and least understood relations in brain and behavior is the lateralization of language to the left hemisphere in most right-handed homo sapiens. The control of both language and righthand motor coordination in the left hemisphere and the degree to which these asymmetries are more pronounced in the human species than in any other (for review, see Hellige 1993) has led to claims that (1) unspecified characteristics of the left hemisphere make it more suitable for the development of language and motor skill than the right hemisphere and (2) understanding these characteristics will be useful in formulating cognitive principles of brain organization. To this end, thousands of papers and hundreds of books have been written examining the distribution of and the basis for brain and behavior asymmetries. Although a number of

DOI: 10.1111/j.1749-818X.2007.00006.x

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@article{Baynes2007ThreeCO, title={Three Conundrums of Language Lateralization}, author={Kathleen Baynes and Debra L. Long}, journal={Language and Linguistics Compass}, year={2007}, volume={1}, pages={48-70} }