THE BILINGUAL BRAIN - PROFICIENCY AND AGE OF ACQUISITION OF THE 2ND LANGUAGE

Functional imaging methods show differences in the pattern of cerebral activation associated with the subject's native language (L1) compare d with a second language (L2). In a recent PET investigation on biling ualism we showed that auditory processing of stories in L1 (Italian) e ngages the temporal lobes and temporoparietal cortex more extensively than L2 (English), However, in that study the Italian subjects learned L2 late and attained a fair, but not an excellent command of this lan guage (low proficiency, late acquisition bilinguals), Thus, the differ ent patterns of activation could be ascribed either to age of acquisit ion or to proficiency level, In the current study we use a similar par adigm to evaluate the effect of early and late acquisition of L2 in hi ghly proficient bilinguals. We studied a group of Italian-English bili nguals who acquired L2 after the age of 10 years thigh proficiency, la te acquisition bilinguals) and a group of Spanish-Catalan bilinguals w ho acquired L2 before the age of 4 years thigh proficiency, early acqu isition bilinguals), The differing cortical responses we had observed when low proficiency volunteers listened to stories in L1 and L2 were not found in either of the high proficiency groups in this Study, Seve ral brain areas, similar to those observed for L1 in low proficiency b ilinguals, were activated by L2, These findings suggest that, at least for pairs of L1 and L2 languages that are fairly close, attained prof iciency is more important than age of acquisition as a determinant of the cortical representation of L2.