Towards a Neurophysiology of Language

Abstract

Scientific study of the relationship between language and the human brain started in the second half of the nineteenth century, as one of the many aspects of experimental medicine, and, in particular, of experimental physiology [1]. There is no need to retell a story that has already been told several times (for an excellent, very readable review, see [2]). The specific limitation in the case of language was, of course, that experimental studies in animals are not possible. However, an answer to this obstacle came from clinical neurology, when several astute physicians, whose names form the Hall of Fame of neuropsychology, such as Broca and Wernicke, inaugurated systematic application of the anatomico-clinical method to the study of language disorders. The logic of this approach took advantage of those accidents of nature, i.e., spontaneously occurring brain lesions. Information gathered from observations of the clinical picture, combined with knowledge about the location of the lesion in the brain, allowed the “localization” of cognitive functions to discrete brain regions. In the case of language, this led to the development of the classical Wernicke-Lichtheim model of word processing, which still finds an honorable place in practically every textbook dealing with aphasia [3]. The model’s fortunes and, in general, those of what Head called the “diagram-makers,” have fluctuated over the years—with eclipses during the golden age of gestalt psychology and, sometime, later, by the advent of behaviorism [4]. What is important to underline here is that acceptance of the idea that complex aspects of language, such as syntax, or the lexicon, could be localized to specific brain areas has gone largely unchallenged well into the era of cognitive neuroscience.