“They were muddy in, muddy out,” says Merzenich. Improper hearing led to weaknesses in all the language tasks, so they were weak in vocabulary, comprehension, speech, reading, and writing. Because they spent so much energy decoding words, they tended to use shorter sentences and failed to exercise their memory for longer sentences. Their language processing was more childlike, or “delayed,” and they still needed practice distinguishing “da, da, da” and “ba, ba, ba.”
Click Here to Get Your Free ChapterExtracts: “They were muddy in, muddy out,” says Merzenich. Improper hearing led to weaknesses in all the language tasks, so they were weak in vocabulary, comprehension, speech, reading, and writing. Because they spent so much energy decoding words, they tended to use shorter sentences and failed to exercise their memory for longer sentences. Their language processing was more childlike, or “delayed,” and they still needed practice distinguishing “da, da, da” and “ba, ba, ba.” Merzenich now became aware of the work of Paula Tallal at Rutgers, who had begun to analyze why children have trouble learning to read. Somewhere between 5 and 10 percent of preschool children have a language disability that makes it difficult for them to read, write, or even follow instructions. Sometimes these children are called dyslexic. Babies begin talking by practicing consonant-vowel combinations, cooing “da, da, da” and “ba, ba, ba.” In many languages their first words consist of such combinations. In English their first words are often “mama” and “dada,” “pee pee,” and so on.
Tallal’s research showed that children with language disabilities have auditory processing problems with common consonant-vowel combinations that are spoken quickly and are called “the fast parts of speech.” The children have trouble hearing them accurately and, as a result, reproducing them accurately. Merzenich believed that these children’s auditory cortex neurons were firing too slowly, so they couldn’t distinguish between two very similar sounds or be certain, if two sounds occurred close together, which was first and which was second. Often they didn’t hear the beginnings of syllables or the sound changes within syllables. Normally neurons, after they have processed a sound, are ready to fire again after about a 30-millisecond rest. Eighty percent of language-impaired children took at least three times that long, so that they lost large amounts of language information. When their neuron-firing patterns were examined, the signals weren’t clear.
Fast ForWord is the name of the training program they developed for language-impaired and learning disabled children. The program exercises every basic brain function involved in language from decoding sounds up to comprehension—a kind of cerebral cross-training. The program offers seven brain exercises. One teaches the children to improve their ability to distinguish short sounds from long. A cow flies across the computer screen, making a series of mooing sounds. The child has to catch the cow with the computer cursor and hold it by depressing the mouse button. Then suddenly the length of the moo sound changes subtly. At this point the child must release the cow and let it fly away. A child who releases it just after the sound changes scores points. In another game children learn to identify easily confused consonant-vowel combinations, such as “ba” and “da,” first at slower speeds than they occur in normal language, and then at increasingly faster speeds. Another game teaches the children to hear faster and faster frequency glides (sounds like “whooooop” that sweep up). Another teaches them to remember and match sounds. The “fast parts of speech” are used throughout the exercises but have been slowed down with the help of computers, so the language-disabled children can hear them and develop clear maps for them; then gradually, over the course of the exercises, they are sped up. Whenever a goal is achieved, something funny happens: the character in the animation eats the answer, gets indigestion, gets a funny look on its face, or makes some slapstick move that is unexpected enough to keep the child attentive. This “reward” is a crucial feature of the program, because each time the child is rewarded, his brain secretes such neurotransmitters as dopamine and acetylcholine, which help consolidate the map changes he has just made. (Dopamine reinforces the reward, and acetylcholine helps the brain “tune in” and sharpen memories.)
“Before he did Fast ForWord,” his mother recalls, “you’d put him at the computer, and he got very stressed out. With this program, though, he spent a hundred minutes (now 30 minutes – editor) a day for a solid eight weeks at the computer. He loved doing it and loved the scoring system because he could see himself going up, up, up,” says his mother. As he improved, he became able to perceive inflections in speech, got better at reading the emotions of others, and became a less anxious child. “So much changed for him. When he brought his midterms home, he said, ‘It is better than last year, Mommy.’ He began bringing home A and B marks on his papers most of the time—a noticeable difference…Now it’s ‘I can do this. This is my grade. I can make it better.’ I feel like I had my prayer answered, it’s done so much for him. It’s amazing.” A year later he continues to improve Because so many autistic children have language impairments, clinicians began to suggest the Fast ForWord program for them. They never anticipated what might happen.
Parents of autistic children who did Fast ForWord told Merzenich that their children became more connected socially. He began asking, were the children simply being trained to be more attentive listeners? And he was fascinated by the fact that with Fast ForWord both the language symptoms and the autistic symptoms seemed to be fading together. Could this mean that the language and autistic problems were different expressions of a common problem? Two studies of autistic children confirmed what Merzenich had been hearing. One, a language study, showed that Fast ForWord quickly moved autistic children from severe language impairment to the normal range. But another pilot study of one hundred autistic children showed that Fast ForWord had a significant impact on their autistic symptoms as well. Their attention spans improved. Their sense of humor improved. They became more connected to people. They developed better eye contact, began greeting people and addressing them by name, spoke with them, and said good-bye at the end of their encounters. It seemed the children were beginning to experience the world as filled with other human minds.
What is remarkable about the cortex in the critical period is that it is so plastic that its structure can be changed just by exposing it to new stimuli. That sensitivity allows babies and very young children in the critical period of language development to pick up new sounds and words effortlessly, simply by hearing their parents speak; mere exposure causes their brain maps to wire in the changes. After the critical period older children and adults can, of course, learn languages, but they really have to work to pay attention. What if it were possible to reopen critical-period plasticity, so that adults could pick up languages the way children do, just by being exposed to them? Merzenich had already shown that plasticity extends into adulthood, and that with work—by paying close attention—we can rewire our brains. But now he was asking, could the critical period of effortless learning be extended?
Merzenich continues to challenge the view that we are stuck with the brain we have at birth. The Merzenich brain is structured by its constant collaboration with the world, and it is not only the parts of the brain most exposed to the world, such as our senses, that are shaped by experience. Plastic change, caused by our experience, travels deep into the brain and ultimately even into our genes, molding them as well—a topic to which we shall return