Chapter 36: history of aphasia: from brain to language.

An historical overview is presented that focuses on the changes both in approach and topics with respect to language disturbances due to brain lesions. Early cases of language disorders were described without any theorizing about language or its relation to the brain. Also, three forms of speech disorder were distinguished: traulotes, psellotes and ischophonia, which are only marginally related to aphasia. In the 18th century some authors, in particular Gesner and Crichton, attempted to explain language disorders in terms of mental processes. The great debate on both the anatomical (Broca, Wernicke) and functional (Wernicke, Lichtheim) aspects of aphasia dominated late 19th century discussion of localization of function, leading to the development of what we now call the cognitive neurosciences. In this period, language processing was described in terms of a simple functional model of word recognition and production; linguistic principles played no role. At the beginning of the 20th century the discussion on language disorders waned due to a decrease of interest in the issue of localization; aphasia became primarily a clinical issue of how best to classify patients. In the second half of the 20th century, the field of aphasia developed rapidly due to studies performed at the Boston Aphasia Unit and, more importantly, to a change of orientation to linguistic notions of language structure, as introduced by Chomsky.