PEOPLE who learn second languages as adults build up new brain areas to
handle the knowledge, according to new American research. But if you learn two
or more languages as a youngster, you incorporate them into the same primary
language area, the study suggests.
Joy Hirsch and her colleagues at the Memorial Sloan-Kettering Cancer Center
in New York studied 12 bilingual people. Six of them鈥攄ubbed 鈥渆arly鈥�
bilinguals鈥攈ad learnt two languages in infancy. The other six were 鈥渓ate鈥�
bilinguals, who mastered a second language between the ages of 11 and 19.
Between them, the volunteers spoke a total of 11 languages, including Korean,
Hebrew, Croatian and Japanese.
While her subjects silently 鈥渟poke鈥� their two languages in turn, Hirsch used
functional magnetic resonance imaging to measure the brain activity in Broca鈥檚
area in the frontal region of the cortex. In this week鈥檚 Nature (vol 388, p
171), her team reports that in early bilinguals, both languages lit up the same
part of Broca鈥檚 area. In late bilinguals, however, two discrete regions about 8
millimetres apart were activated.
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The findings suggest that a primary language centre integrates all the
languages a child is exposed to during an early formative period. But people who
learn new languages at a later date have added to their language system, says
Hirsch: 鈥淲e can see the body building in the brain as a result of this.鈥�
The findings seem at odds with a study in 1995 using positron emission
tomography scans. This suggested that languages are always centred in the same
part of Broca鈥檚 area. However, 鈥渓ate鈥� bilinguals in the 1995 study learnt a
second language at an average age of only seven, matching Hirsch鈥檚 description
of an early bilingual.