http://www.mcgill.ca/newsroom/channels/news/first-language-wires-brain-later-language-learning-257068
You may believe that you have forgotten the Chinese you spoke as a child, but your brain hasn’t. Moreover, that “forgotten” first language may well influence what goes on in your brain when you speak English or French today.
In a paper published today in Nature Communications, researchers from McGill University and the Montreal Neurological Institute describe their discovery that even brief, early exposure to a language influences how the brain processes sounds from a second language later in life. Even when the first language learned is no longer spoken.