Earlier this week, I wrote about how not being able to remember a word, and having it "on the tip of your tongue," appears to be a universal phenomenon. It happens to people in all languages, including people who use sign language. Now, another similar study may have helped scientists understand a little bit more about the brain's language centers.
Two centers in the brain have long been associated with verbal communication: Broca's area, which is thought to be related to speech production, and Wernicke's area, which is associated with comprehending speech. Scientists suspected these areas might be specifically for speaking, because they are located near areas of the brain that are connected to moving the vocal chords, and to the auditory cortex, which is used to hear sounds.
Scientists reasoned that deaf people who use American Sign Language to communicate would use other areas of their brain to create and process language, such as parts located near the visual cortex, used for seeing. But when researchers took PET brain scans of 29 deaf native ASL signers and 64 hearing native English speakers, they found no difference in the brain. In both groups, Broca's and Wernicke's areas were equally active. Spoken or signed, these areas of the brain seem to be responsible for creating and processing language, an unexpected result.
A second, related study wanted to determine whether sign language taps into the same parts of the brain as charades. They wanted to figure out whether the brain regards sign language as more like spoken language, or more like pantomime gestures that mimic an action. The researchers found that the signers activated different parts of their brains when pantomiming versus when signing. Even when the sign is basically indistinguishable from the pantomime – when similar hand gestures are used – the brain treats it like language.
These discoveries suggest that something about language is universal and doesn't depend on whether people use their voices or their hands to talk. The Broca's and Wernicke's areas are tied to language, no matter whether it's spoken or signed. Furthermore, these studies also suggest that the brain was wired for language more than it was wired for speech.