Speech veers left in babies’ brains
By Bruce Bower
In adults, the brain’s left hemisphere usually assumes primary responsibility for understanding speech. A new brain-imaging study suggests that a fledgling version of this left-brain specialization appears in 2-to-3-month-old babies as they listen to speech, even though they can’t utter a word and it’s not clear whether they understand any of what they hear.
Language acquisition may reflect the gradual expansion of a network of left-hemisphere regions that enters the neural fray within the first few months of life, propose psychologist Ghislaine Dehaene-Lambertz of the National Center of Scientific Research in Paris and her coworkers. In newborns, however, it remains unknown whether this left-brain network responds only to speech or to any series of rapidly presented sounds, the scientists note in the Dec. 6, 2002 Science.