There’s a reason why you trip over your tongue when learning a foreign language: The adult brain pigeonholes speech in the left hemisphere, displaying minimal plasticity, according to a new study in the Journal of Neuroscience.
Spanish researchers used fMRIs to track neural activity as participants read, listened to, and spoke new languages over time. They found that as participants gained proficiency, their brains recruited from both hemispheres to read and comprehend; notably, their neural activity patterns for comprehension varied widely from person to person. But speech production remained firmly cornered in the left hemisphere, with minimal change.
Translation: It’s much easier to learn to read and understand than it is to speak fluently. This also suggests that speaking is hardwired to the left hemisphere, while comprehension is flexible, engaging more plasticity.