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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 writ- ing that lodge in unrelated neural tissues. Her unusual inner strug- gle 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.Õs condition demonstrates - is scattered across both hemispheres. Before V.J.Õs 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, interfer- ing 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 bio- logically 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 have 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."

Go ahead, read it again.

Now say it out loud.

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 rec- ognize 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 Òcat.Ó 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 charac- ters themselves. Some poor readers may stumble because they can- not 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 schoolreading program. Scientists are still trying to understand what the brain does that may be unique to reading, as opposed to the more general cogni- tive 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 lan- guage 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 hemi- spheres 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 func- tion 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.

Some Reading Disorders

Developmental dyslexia: A person has a problem with speech sounds and decoding single words while reading. The meaning and order of words (syntax and semantics) are understood. Intelligence is not affected and may be in the superior or gifted range.

Language-learning disability: This problem affects all aspects of language, starting at the level of decoding and comprehen- sion. Verbal intelligence is greatly affected and may be in sub- average range.

Acquired alexia: Reading ability is lost or diminished because of trauma, tumor or stroke.

Hyperlexia: The ability to recognize words is significantly bet- ter than reading comprehension. Exceptional word-recognition ability is apparent by age 5, but reading comprehension is very poor. Reasoning and abstract problem-solving are difficult.

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, MM researchers discov- ered 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 pro- cessing 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. 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 Corporation to market a regi- men 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 effluent 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 confi- dently design a classroom curriculum based completely on neuro- science, 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 defini- tive answers to three basic questions:

- I Sow do people learn to read?
- What prevents people from reading well?
- What can anyone do about it?

The Reading Brain

The brain is designed to talk, not read. To read well, different areas of the brain must decode text by translating letters into the speech sounds. Only then can the brain identify the word the letters repre- sent and draw on the brain's general cognitive processes to find its meaning. Brains of people with dyslexia process visual movements and pat- terns differently from normal readers, brain scans show.

Highlighted areas indicate greater activity.

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