A team of scientists from Milan and Leipzig succeeded in imaging the brains of two-day-old infants. They report that although the brain structures for language are already in place in these newborns, there are significant differences between these structures and those found in adults.
Their paper just published in the American journal Proceedings of the National Academy of Sciences caught my attention.
We know that the infant's brain, weighing only about 300 grams, is tiny compared with an adult's. But it grows at an astounding rate, tripling its size in the first two years of life, eventually reaching some 1,400 grams when mature. Thanks to the European research, we now know that the brain not only grows in size, but also reorganises itself in important ways to learn about the world.
Research on the brain over the past century and a half has shown that for most of us, the left hemisphere plays a more dominant role in language than the right hemisphere. Pioneering scientists in France and Germany in the 19th century identified regions for language production and comprehension, and for reading. All these regions are in the left hemisphere.
With today's powerful methods of brain imaging, we now know that language goes much deeper than the regions on the brain's surface observed by the early pioneers. Language is much more a whole-brain activity, involving many neural circuits operating deep below the cortex. The European research makes full use of the latest imaging technology in this infant study.
How neural language circuits eventually form depends critically on the nature of the language they support. For instance, the brain of someone who grows up speaking Chinese is surely different from the one of an English-only speaker since the auditory circuits must distinguish word tones and the visual circuits must read Chinese writing. Shaping the brain for a particular language comes later than the general ability for language. Initially the infant must come prepared to learn any language - Cantonese if born in Hong Kong, and English if born in London.
In comparing infant brains with those of adults, the European scientists found that basic structures are all already in place at the age of two days.