New research offers fresh insight into how the first language we learn affects our experience of all the subsequent ones we come across. Scientists in Canada have found that our original language creates certain patterns in the brain that are perhaps never lost.

The influence of this 'locking in' of the brain is still evident even when all knowledge of the first language has disappeared from memory. It appears to inform the way we hear the sounds and words of subsequent languages we come into contact with during our lives, as though our brains have become hardwired in one particular formation or tuned to one particular language.

The team from McGill University and the Montreal Neurological Institute looked at three groups of adolescents: those who only speak French, those who speak both French and Chinese fluently, and adopted teens who originally knew Chinese as babies but now only speak French. MRI scans were used to monitor brain activity while French pseudo-words were played. Interestingly, the same areas of the brain 'lit up' in the bilingual speakers and the monolingual speakers who originally knew Chinese.

In those who had known Chinese at a very early age but are no longer bilingual, their brains handled words as if they still were. The researchers think this could help us understand more about how we learn languages and how that process changes as we get older.

"The adopted children we tested have an interesting background because they were exposed to one language from birth, but completely discontinued that language at a young age when they were adopted into families who speak a different language," said one of the researchers, Lara Pierce. "This is very interesting from a language development perspective because it allows us to look at the influence of just that very early period of language development on later language processing, separately from the effects of ongoing exposure to one or more languages."

It may help explain why learning a language as a baby is so effortless and why it becomes much harder later in life, at least for some of us: our brains have already been 'set' in a certain configuration. As Pierce notes, very young children have been shown to be incredibly adept in picking out words that help in their language learning and dismissing other sounds - a skill we tend to lose in later life.

The study has been published in Nature Communications.