When it comes to grammar, a part of the brain called Broca's area can instinctively tell right from wrong, according to a new study. This sentence-savvy structure is increasingly active as people become adept with a set of grammatical rules for a language they don't know. The finding lends support to the notion that a universal grammar common to all languages is embedded in our brains.
Babies readily pick up grammar from listening to language, even though parents don't explicitly teach them complex linguistic rules. Researchers have argued that this remarkable feat comes about because neural circuits are laid out to recognize rules that correspond to a universal grammar, a set of principles that some linguists argue underlies every human language. The responsible brain structures were not known, but Broca's was a candidate because it is essential for speech.
Mariacristina Musso, a neurologist at the University of Hamburg, Germany, and her colleagues studied the brain activity of 16 native German speakers while they looked at short sentences in either Japanese or Italian, languages they'd never studied. Before the experiment the subjects learned a set of either Italian or Japanese words by heart. They then had to learn six grammatical rules for Japanese or Italian, which were briefly explained in German. Unknown to the subjects, three of the rules were genuine, the others phony. The volunteers were then presented with sentences that were made up of the previously memorized words. The phrases either followed one of the six rules or were slightly off. While lying in a functional magnetic resonance image scanner, subjects had to decide whether or not one of the six rules applied to the sample sentence.
The scientists report in the July issue of Nature Neuroscience that Broca's area leapt into action when subjects judged sentences generated according to genuine rules but not phony rules, suggesting that Broca's area only learns rules that fit the universal grammar, says Musso.
“These are intriguing results,” says cognitive scientist Gary Marcus of New York University, but he says the study isn't enough in itself to establish whether Broca's area is the region that learns universal grammar. He says that additional experiments are needed to demonstrate that the increased activity is truly related to the mastering of real grammatical rules.