In Art of Language, the Brain Matters
Discovery: New techniques let researchers observe brain activity as children read.
Understanding how the mind works could reshape classroom instruction.
By ROBERT LEE HOTZ, Times Science Writer
Los Angeles Times
For generations, teachers have struggled to correct the reading disorders that handicap one in every five Americans with little more than theory and the informed intuition of trial and error to guide them.
Now, by probing the neural processing of written words, researchers for the first time are discovering the true character of reading problems.
Surprisingly, they are finding that to every human brain--tailored by evolution to communicate through speech--reading is an unnatural act.
As the eye chases a sentence across the page, the brain must perpetually orchestrate neural systems crafted by nature for entirely different tasks, new research shows. So quickly must the brain work that the difference between a good reader and a poor reader may be measured in thousandths of a second.
Complicating the process are mental differences in how men and women read; in the brains of those who read poorly and those who read well; even between the same person reading aloud and reading silently. And, unexpectedly, the neurological roots of reading problems may develop well before toddlers are ever introduced to the alphabet.
Already, scientists are learning to correct reading disorders by directly attacking the neural processing problems that cause them, actually changing the physical structure of the brain. Indeed, several leading brain researchers are marketing computerized training programs that remold a child's crucial neural circuits, taking advantage of the brain's remarkable ability to rewire itself.
These new discoveries offer a glimpse into the future of reading reform, in which classroom instruction would be based on an intimate scientific understanding of how the brain works.
"In the past, educational methods . . . have never been based on neuroscience or any research based on an understanding of how the brain actually learns," said UCLA neuropsychologist Susan Y. Bookheimer, who studies language disorders and the brain. "This is something fundamentally different."
At a time when debates over the best way to teach reading are waged with ideological fervor in elementary school classrooms, the systematic study of the brain offers the best hope of solving the problems caused by learning written language, experts say.
Reading problems affect as many as 8 million children between the ages of 4 and 13, with an additional 800,000 poor readers diagnosed every year, NIH experts said.
If not corrected by age 9, a reading problem will become a lifetime struggle, according to Yale University studies. New research by Harvard University scientists shows that people diagnosed as poor readers in elementary school still have not caught up on their reading skills even 30 years later.
"In the long run, the only way to make really serious progress is to develop a thorough scientific understanding of what is going on in the brain," said Stanford University neuroscientist David Heeger, who studies how the brain visualizes letters and words.
Such progress does not come easily--or cheaply. The National Institute of Childhood Health and Human Development has been steadily spending about $21 million a year on research projects that so far have studied 38,000 readers. Teaching experiments are underway at 266 schools.
But even so, the gap between the laboratory and the classroom remains all but unbridgeable, experts said, due to long-standing disagreements over the ultimate causes of reading failures. In addition, some research is so new that educators simply have not had time to digest its ramifications.
Those who study language and the brain say that poor readers are being diagnosed incorrectly or too late, taught improperly or not intensively enough. Their problems often are misunderstood, even by those trying hardest to help them.
"What we know already from research is not being applied in instruction," said language expert Jack M. Fletcher at the University of Texas-Houston.
New Technique Offers a Window on the Brain
For the first time, researchers are able to study the living brains of children and adults directly.
This revolution in reading research is being driven in large measure by a new generation of noninvasive imaging techniques that allow monitoring of rapid, subtle shifts in mental activity as people read.
"Scientists are euphoric that we have a technology that allows us to look at brains of people while they are reading," said neurologist Bennett A. Shaywitz, co-director of the Yale University Center for the Study of Learning and Attention. Like UCLA, Yale is using brain scanners to study children who have trouble reading.
"The imaging technology takes a hidden disability and makes it visible," Shaywitz said.
The result is a cascade of surprising new neurobiological insights. Scientists are finding that reading:
Depends on two separate but equally important neural systems involving sound and pictures. The brain reads primarily by translating written characters into the phonological building blocks of spoken language. But the brain also links a memorized picture of a complete written word to its meaning, recalling it in a way that bypasses the need to sound out the word.
Is a matter of timing. Experts at Rutgers University have shown that to read well, the brain has only a few thousandths of a second to translate each symbol into its proper sound. Most children can process such sounds in less than 40 milliseconds, but language-impaired children may need up to 500 milliseconds--fast enough to speak fluently, but too slow to read well.
Depends on keeping the mind's eye in focus. Scientists at Harvard, Georgetown University and Stanford University are finding that minor differences in how the brain handles the visual processing of images, color, fast motion and contrast can impede reading. Again, the speed of the visual processing may be crucial.
Is different for men and women. Men do not use their brains the same way to read as women do, Yale researchers demonstrated, yet both sexes are equally afflicted with reading troubles. Nonetheless, boys may be diagnosed more often with reading disorders than girls.
Appears to make the brains of people who read poorly function differently than those who read well, in some ways making them work harder. Yet researchers at Dartmouth, UC Davis and other centers believe that everyone has some trouble adjusting to the written word because it makes such taxing demands on so many different parts of the brain.
Moreover, reading disorders originate in children much earlier than previously believed--often years before they are diagnosed in school and well after they most readily may be corrected, language experts at UCLA, Harvard, Rutgers and the University of Texas said.
Reading simply does not come naturally to anyone.
And what many reading experts traditionally diagnosed as a learning disability arising from a physical defect may instead result from normal variations in how individual brains work.
"Reading problems are an expression of an entirely normal brain; it is just that different brains have different abilities," said Judith L. Lauter, director of the Center for Communication Neuroscience at the University of Oklahoma.
Indeed, the simple act of reading a book may be one of the most challenging tasks the brain must perform, the new findings of neuroscience suggest.
"Reading does not just happen," said UC Davis neurology expert Kathleen Baynes. "It is just a terrible struggle."
Our Biological Destiny: Speaking, Not Reading
The anatomy of reading is shaped by that struggle.
Consider a 45-year-old San Jose housewife known to the scientific world as V.J. To cure severe epilepsy, she recently underwent an unusual operation that surgically separated the hemispheres of her brain.
When it comes to reading, she is today of two minds.
The left side of her brain can read things it cannot write. The right side of her brain can write things it cannot read.
For researchers investigating how people read, she is stark evidence of the special place that written words occupy in the brain, divided by the learning process into the separate acts of reading and writing that lodge in unrelated neural tissues. Her unusual inner struggle to read and write is a living demonstration of the extremes to which written language drives every human brain.
While 90% of right-handers process speech and language in the left side of their brain, about 30% of left-handers--like the patient V.J.--process language in the right side of their brain.
But written language--as V.J.'s condition demonstrates--is scattered across both hemispheres.
Before V.J.'s surgery, her left and right hemispheres worked together seamlessly to coordinate reading, writing and speaking. Now that the halves of her brain can no longer communicate, her left hemisphere attempts to control her language abilities, interfering with her ability to read and write.
Unlike speech, written language is an invention so recent that the brain has yet to develop any dedicated neural machinery to handle it. Consequently, it straddles the brain in a way that language alone does not.
Said Fletcher at the University of Texas-Houston, "Speech is a biologically evolved skill. We have had speech for 4 million years. We have had written language for 4,000 years. We are biologically destined to speak, but not to read or write."
Neuroscientist Michael S. Gazzaniga at Dartmouth said the efforts of the brain to adapt to the cultural demands of written language has a profound effect on its neural structure. "Reading is an invention that is going to have a different neurology to it than the things that are built into our brain, like spoken language," he said.
The case of V.J., he said, shows how much learning to read and write alters the brain from the more natural structures that all human brains long ago evolved for spoken language.
No one is sure why the process of using written symbols to express a thought should be so separated from the process of extracting meaning from those same symbols or what it may mean in terms of reading ability.
"Reading is a bizarre skill--and a very complex process," said Harvard neuropsychologist Alfonso Caramazza, who studies the neurobiological basis of language.
A Good Reader's Lopsided Brain
Look at the word "cat."
Could you detect any difference in your mind when you saw it, read it and then spoke it?
Almost certainly not.
But each time, the brain employed quite different neural circuits to perform each task, new brain imaging studies show.
Even as simple a word as "cat" can make the reading brain stumble.
Reading comprehension depends on the ability to decode and recognize single words rapidly and accurately. Any mental hesitation can destroy the high-speed flow on which reading depends.
So far, researchers have identified three neural problems that may make it harder for people to read well:
The inability to identify and sound out properly the internal sounds, called phonemes, that make up words. English depends on the sounds of 44 phonemes and uses only 26 letters to encode them. There are three phonemes in "cat." Many poor readers have a hard time processing these phonological cues.
The inability to make those auditory distinctions rapidly enough. Some brains may process information too slowly and may not be able to distinguish between the sounds from which words are composed.
The inability to quickly resolve the visual patterns of the characters themselves. Some poor readers may stumble because they cannot process visual information fast enough to scan letters on a page.
"Mapping a single letter or cluster of letters to a sound may be the most difficult skill in reading," said Caramazza at Harvard.
Those educators who have championed phonics instruction are especially heartened by the new research because it highlights the importance of teaching the building blocks of words as part of any school reading program.
Scientists are still trying to understand what the brain does that may be unique to reading, as opposed to the more general cognitive chores of memory, attention, pattern recognition, auditory processing and categorization.
The visual process involved in recognizing letters, for example, may make use of older neural circuits that originally evolved for recognizing faces.
"The challenge for the brain is to take these basic building blocks and then assemble them in some way to compute a meaning," said UC Berkeley linguist George P. Lakoff, who is working on a neural theory of language.
Some brain-imaging studies conducted by researchers at Rutgers have suggested that the left side of the brain is faster at processing information than the right side, which may be an important skill when it comes to separating the sounds embedded in speech into distinct units.
That may be why language generally favors the left side over the right side.
Certainly, researchers have found that children with normal language skills appear to have lopsided brains--the left side is bigger and more active than the right. Children with language disorders appear to have more physically balanced brains, with both hemispheres being of equal size and activity.
Some researchers now believe that such physical differences may arise before birth as the developing fetus is exposed to varying levels of the hormone testosterone.
Even when brains appear to be physically similar, they may function in quite different ways.
Imaging studies that compared how men and women recognize words, sound them out and extract their meaning found striking variations in how people read, based on their gender.
Men tended to read with the left side of their brain; women tended to activate both sides of their brain.
The Yale researchers who conducted the study believe that those who depend most on the left hemisphere take in text in a more global way. Those who use both hemispheres may take in text bit by bit.
In the same way, the brains of many poor readers--especially dyslexics--appear to function differently than those of normal readers, researchers at Wake Forest University Baptist Medical Center recently discovered.
In any case, the brain is so attuned to speech that even for those who grew up without any ability to hear, the neural circuits that handle their sign language still are those usually crucial for any spoken tongue.
Nonetheless, when reading English, those same deaf people appeared to use a different part of their brain than hearing people did.
None of the language structures on the left side of the brain were activated. Instead, regions of the right parietal and temporal lobes lit up, reflecting perhaps a greater sensitivity to visual and spatial skills when responding to the shape of a letter.
Researchers aren't certain what the difference means, only that it may hold one more clue to the mystery of reading.
Another part of the reading enigma can be found in how blind people read Braille, using their fingers to find the meaning in printed characters.
In a study of how people blind from birth read, NIH researchers discovered that the visual parts of a blind person's cortex were activated as the reader's fingers ran across the Braille characters--despite the absence of any visual input.
And when the researchers temporarily disrupted those visual processing areas in the cortex by using special magnets, the blind test subjects made mistakes as they scanned Braille with their fingers, said John Mazziotta, director of the UCLA brain-mapping division.
They reacted as if something had passed in front of their eyes, blocking their view of the letters. In effect, their fingers blinked.
Using Games to Retrain Neurons
Researchers now realize that children learn to read with some of the same neural skills they use to learn to speak, underscoring the critical importance of phonics instruction as part of any classroom instruction.
Scientists also are starting to learn how changing the ability to read may alter the brain itself. A few experts, impatient with the pace of traditional speech therapy and reading instruction, are designing neural therapy to train better readers.
"The more you try with traditional methods, the worse it gets," said Rutgers language expert Paula Tallal, who recently founded a company called Scientific Learning Corp. to market a regimen of computerized instruction for children with reading, writing and overall language problems.
Working with UC San Francisco brain expert Michael Merzenich, Tallal's group created computer games meant to retrain the neurons and synapses of the reading brain. Hidden in the games are special tasks that strengthen auditory processing speed, working memory, phonological awareness and the other skills of fluent reading. Only by repeating the tasks thousands of times for weeks are changes wrought in the structure of the brain.
To date, nearly 10,000 children have taken the four-to-eight-week course, with many of them showing improvements of up to two years' gain in their reading level, published research indicates.
But it still may be a decade or more before scientists can confidently design a classroom curriculum based completely on neuroscience, cautioned Reid Lyon, the neuropsychologist who oversees the federal reading research effort.
Despite the avalanche of new scientific knowledge about reading and the brain, Lyon said, researchers are still searching for definitive answers to three basic questions:
How do people learn to read?
"Making the connection from the brain to the classroom is a stretch, still," Lyon cautioned. "We are far, far away from looking at what we have learned about the brain to helping teachers understand what to do in the classroom."
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