Cognitive neuroanatomy of language: The contribution of functional neuroimaging

Abstract

This paper summarizes results obtained to date using the new brain functional imaging techniques (mainly positron emission tomography) in several domains pertaining to the issue of brain/language relationships. Up to a few years ago, most of our knowledge in this area was derived from classical observations of patients with various language disorders following brain damage, so that inferences from this model as a normal brain function could have been misleading and ultimately prove erroneous. Following the seminal work of the Saint-Louis group in the late 1980s, a great deal of literature is currently accumulating, including studies of various aspects of language functions (expression, comprehension, memory, etc.). This new approach has already led to challenge of some previously widely held dogmas such as the role of Wernicke's area in verbal comprehension and the role of Broca's area in language production. At the same time, some studies have yielded unexpected results suggesting, for instance, a special role of inferior lateral parts of the left frontal lobe in semantic and/or voluntary aspects of language processing. Among other studies, those concerning the mechanisms of verbal short-term memory have provided interesting results. Finally, the emergence of a new mode of reasoning about brain/language relationships may greatly modify our experimental as well as clinical approaches to aphasic patients.