The human brain has a remarkable capacity for interpreting speech, with large areas of the brain given over to tracking the sound and interpreting it as language. The neurons that manage this capacity are put in place during our embryonic development, and these are able to respond to sounds shortly after birth. But now, a new study looked at brain activity in premature infants, and it showed the networks that respond to syllables are already active well before most infants are normally born.
What makes this all the more remarkable is the networks are still under construction at that time. The work relied on infants born at about 30 weeks of gestation (normally, birth comes at about 38 weeks). These babies are typically so young they spend most of their time in an intensive care unit, so it’s not possible to take them to an MRI tube to track their brain’s function. Instead, the researchers took advantage of the human body’s relative transparency to certain infrared wavelengths.