Language and the Brain

For the 90% of people who are right-handed, language is stored and controlled by the left cerebral cortex, although for some left-handers this pattern is reversed. These differences can easily be seen in the results of neuroimaging studies that show that listening to and producing language creates greater activity in the left hemisphere than in the right. Broca’s area, an area in front of the left hemisphere near the motor cortex, is responsible for language production. This area was first localized in the 1860s by the French physician Paul Broca, who studied patients with lesions to various parts of the brain. Wernicke’s area, an area of the brain next to the auditory cortex, is responsible for language comprehension.

Video 9.3 Language and the Brain reviews major brain structures and functions involved in language.

Activation of Language Brain Areas

Scientists wanted to know if Wernicke’s and Broca’s areas were active when children learn language (Kuhl, 2010). To find out, they used a brain imaging tool called magnetoencephalography (MEG) which is harmless, noninvasive, and silent and provides scientists with a millisecond-by-millisecond reading of what parts of the brain are active during a specific time period.

In one MEG study, newborns, 6-month-olds, and 12-month-olds listened to speech sounds while they sat in the MEG machine. The MEG measured infants’ brain activity in Wernicke’s and Broca’s areas while they listened to those speech sounds.

The activity from all of the infants’ brains in the study was averaged together. Researchers found that, while listening to language sounds, the region of the brain that is important for speech perception—Wernicke’s area—was active in newborns, 6-month-olds, and 12-month olds.

In newborns, the region of the brain important for speech production—Broca’s area—didn’t showing activity. This makes sense. In newborns, the language perception and language production regions aren’t yet coordinated.

Only six months later, the language perception and production regions of the infant brain are active at the same time. This is just around the time that infants are learning to babble.

But the infants aren’t actually babbling while they are in the MEG. They are just listening silently to language sounds. It is as if the infant brain is practicing while listening, trying to figure out how to produce all the sounds it hears every day. This pattern of brain activity suggests that the speaking and listening parts of the infant brain are beginning to work together. Over the past six months, connections between these two brain regions have grown. The connections have strengthened as the infants listened to language.

At 12 months, many infants are beginning to say their first words. By this age, simultaneous activity in both the production and perception areas of the brain is even stronger.

This coordinated brain activity is the result of both biology and experience. Early experiences with language are especially critical for infants. The infant brain is beginning to connect and coordinate these regions long before they utter their first word.