The ability of bilingual people to read or hear a particular language, and respond using that language alone, suggests some kind of language-specific system in the brain. But the same areas of the brain are active no matter what language someone is using. Now, though, Wellcome Trust Senior Research Fellow Professor Cathy Price and colleagues at the Institute of Neurology have identified an area of the brain that is active when a person switches from one language to another.

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In the group's study, 25 German–English speakers and ten Japanese–English speakers were shown pairs of words and told to ignore the first one (the primer). The words were either related (e.g. bathtub–SHOWER) or not (e.g. bathtub–SPOON). When the words were related, brain activity in language areas was typically lowered, as the brain had been 'primed' to be thinking about that subject.

Sometimes the related pairs were in the same language (e.g. trout–SALMON) and sometimes in different languages (e.g. forelle–SALMON). The researchers could thus identify whether areas of the brain were responding just to the meaning of the words or were also sensitive to a change in language in which they were presented.

Using functional imaging techniques, the team detected one area that responded to both the switch in language and the meaning of the words – the head of the left caudate. Researchers think that this area could be important in telling the brain which language to respond in.

Interestingly, bilingual people with damage to this area of the brain are known to have problems switching between languages. The team will now to try to piece together this language-sensitive circuit in the brain by examining individuals with damage in this and other brain areas.

Image: Professor Cathy Price

External links

• Crinion J et al. Language control in the bilingual brain. Science 2006;312(5779):1537–40.