The bilingual brain: Cerebral representation of languages

The present article deals with theoretical and experimental aspects of lang uage representation in the multilingual brain. Two general approaches were adopted in the study of the bilingual brain. The study of bilingual aphasic s allows us to describe dissociations and double dissociations between the different subcomponents of the various languages. Furthermore, symptoms pec uliar to bilingual aphasia were reported (pathological mixing and switching and translations disorders) which allowed the correlation of some abilitie s specific to bilinguals with particular neurofunctional systems. Another a pproach to the study of the bilingual brain is of the experimental type, su ch as electrophysiological investigations (electrocorticostimulation during brain surgery and event-related potentials) and functional neuroanatomy st udies (positron emission tomography and functional magnetic resonance imagi ng). Functional neuroanatomy studies investigated the brain representation of languages when processing lexical and syntactic stimuli and short storie s. Neurophysiologic and neuroimaging studies evidenced a similar cerebral r epresentation of L1 and L2 lexicons both in early and late bilinguals. The representation of grammatical aspects of languages seems to be different be tween the two languages if L2 is acquired after the age of 7, with automati c processes and correctness being lower than those of the native language. These results are in line with a greater representation of the two lexicons in the declarative memory systems, whereas morphosyntactic aspects may be organized in different systems according to the acquisition vs learning mod ality. (C) 2001 Academic Press.