Neuroscientists used an instrument called functional MRI to study the brains of two groups of bilingual people. One group consisted of those who had learned a second language as children. The other consisted of people who learned their second language later in life. When placed inside the MRI scanner, which allowed the researchers to see which parts of the brain were getting more blood and were thus more active, people from both groups were asked to think about what they had done the day before, first in one language and then the other.
    The researchers looked specifically at Broca’s area, in the left frontal part, which is believed to manage speech production. The two groups of people demonstrated different uses of their Broca’s area. People who learned a second language as children used the same region in Broca’s area for both languages. But those who learned a second language later in life made use of a distinct region in Broca’s area for their second language—near the one activated for their native tongue.
    Researchers concluded that when language is being hard-wired during development, the brain may
intertwine sounds and structures from all languages into the same area. But once that wiring is complete, the management of a new language, with new sounds and structures, must be taken over by a different part of the brain.