Growing up in the suburbs of New York City, Takao Hensch learned German from his father, Japanese from his mother and English from the community around him. “I was always wondering,” he says, “what is it that makes it so easy to learn languages when you’re young, and so hard once you begin to get older?” Today, as a neuroscientist at Boston Children’s Hospital in Massachusetts, Hensch is at the forefront of efforts to answer that question in full molecular detail. Language acquisition is just one of many processes that go through a ‘sensitive’ or ‘critical’ period — an interval during development when the neural circuits responsible for that process can be sculpted, and radically changed, by experience (see ‘Open and shut’). During critical periods, children can make rapid progress at discerning facial features that look like their own, recognizing spoken language and locating objects in space. But within a few months or years, each window of opportunity slams shut, and learning anything new in that realm becomes difficult, if not impossible. (via Neurodevelopment: Unlocking the brain : Nature News & Comment)
