While researching written language and autism for my doctoral degree, I learned a small fraction of what scientists now understand regarding language cognition. The question I had, and one many others have, is why some autistics are good at written or symbolic language communication, but have either limited verbal abilities or are non-verbal? How can someone write and not speak? Why would someone prefer sign language or pictographs to speaking, especially if he or she can speak?
The simplified answer: language is not one thing. Language that is seen is not the same as language that is spoken and heard. Symbolic language and auditory language differ. Braille involves yet another form of language cognition. Somehow, our brains manage to connect and decipher several different "languages" we experience.
Most people can "read" postures, expressions, icons, symbols, colors, sounds, gestures, vocal tones, spoken words, and written words. If you've ever listened to "Peter and the Wolf" you realize that sounds are a language, conveying human emotions and attitudes. Language is so many things that it is astonishing we manage to communicate so efficiently.
Language cognition involves several regions of the brain. Two major regions involved are the Exner and the Broca. These two regions demonstrate an ability to work separately, but in most people they work together to aid in spoken and written language communication.
The Broca is about an inch from the surface of the left frontal lobe, where it is well protected. The problem is that head trauma often does affect this small, delicate region and speech is adversely affected.
From Brainmind.com is a good explanation:
The importance of Broca's area and the left frontal lobe has also been demonstrated through functional imaging. For example, the left frontal lobe becomes activated during inner speech and subvocal articulation (Paulesu, et al., 1993; Demonet, et al., 1994). The left frontal lobe also becomes highly active when reading concrete and abstract words (Buchel et al., 1998; Peterson et al., 1988), and when engaged in semantic decision making tasks (Demb et al., 1995; Gabrielli et al., 1996). Moreover, activation increases as word length increases and in response to long and umfamiliar words (Price, 1997).Recent scans of infants have shown that those later diagnosed with autism do have different connection patterns from the Broca region to other parts of the brain. Most importantly, the Exner region is poorly "wired" to the Broca. One of the most amazing things about the Broca is that it seems to contribute to recognizing a sense of "self" and "other" when communicating. As a report in National Geographic stated:
But as scientists are learning about all higher cognitive functions, they're discovering that a sense of self is not a discrete part of the mind that resides in a particular location, like the carburetor in a car, or that matures all at once, like a flower blooming. It may involve various regions and circuits in the brain, depending on what specific sense one is talking about, and the circuits may develop at different times.The Exner region sits sort of above and behind the Broca region. They are normally connected and interact. That's why many children read aloud at first, then slowly decrease the "aloud" until there are no vocalizations. Most humans process speech easier than written words, so the speech region "helps" the symbolic region translate symbols into meaning. In *some* (and only *some*) autisms, the process is "short-circuited" (literally) and the speech area is unable to assist. However, the symbolic and pattern-based area of the brain excels. The autistic might excel at pattern recognition and rules-based systems, which is the core of written language. Writing is more pattern-based than speaking.
How do these two relate? Again, from Brainmind.com, is a good explanation:
Exner's Writing Area is located within a small area along the lateral convexity of the left frontal lobe, and is adjacent to Broca's expressive speech area, and the primary and secondary areas controlling the movement of the hand and fine finger movements. Exner's area appears to be the final common pathway where linguistic impulses receive a final motoric stamp for the purposes of writing. That is, Exner's area translates auditory-images transferred from the posterior language areas, into those motor impulses that will form written words and sentences. Exner's area is very dependent on Broca's area with which is maintains extensive interconnections. That is, Broca's area also acts to organize impulses received from the posterior language zones and relays them to Exner's area for the purposes of written expression.Imagine what happens when the Exner and Broca regions do not "interface" properly. Even a minor disruption or delay in the connections between these areas of the brain can cause impaired language development and cognition difficulties. In many people with seizures, this is precisely what happens: the auditory and the symbolic don't connect. Abstractions are lost. Metaphors and figurative language are reduced to memorization, not the instantaneous decoding that most people perform subconsciously. Anything that isn't a concrete, exact thought has to be thought about as a puzzle to solve consciously. The delays required impair social communication.
As scientists conduct more and more research on language and the brain, we are likely to find some keys to some forms of autism. Language cognition is a significant factor in social connections and human interactions. When language fails us, or at least challenges us, we are likely to be challenged in countless other aspects of life.
Consider this, also from National Geographic:
Fifteen-year-old Tito Mukhopadhyay squats beside his mother on his bed, rocking, his hands flapping wildly. The gestures are typical of a severely autistic individual, as are his avoidance of eye contact and his unintelligible grunts and moans. But Tito is far from inarticulate. A visitor asks him why he is moving about so much.
"I know it looks different," he answers, using a pencil and paper to scrawl his reply. "But I got into this habit to find and feel my own scattered self."
Initially diagnosed as mentally retarded, he was dragged from one doctor to another in his native India by a mother desperate to find the cause of her son's abnormal behavior and language impairment. Through relentless, sometimes unorthodox, training she broke through the barrier of silence, teaching Tito to add and subtract, to enjoy literature, and eventually to communicate by writing, at first by tying a pencil to his hand. Because of her efforts Tito, rare among low-functioning autistics, can describe with powerful clarity what the condition feels like from the inside.
Tito's vivid autobiographical reflections reveal a sensibility and intelligence greater than his years. In Beyond the Silence, written between the ages of eight and eleven and published in England in 2000 (published as The Mind Tree in the U.S. in 2003) he chronicles his early attempts to cope with the cacophony of disconnected information arriving through his senses and his profound struggle to control his own body and behavior. He wrote of two distinct selves, a thinking self "which was filled with learnings and feelings," and an acting self that was "weird and full of actions," over which he had no more control than if it belonged to another person altogether. "The two selves stayed in their own selves, isolated from each other."
"Tito's remarkable achievements haven't overcome his autism," says Michael Merzenich, a neuroscientist at the University of California, San Francisco, who has studied Tito. "There is still chaos occurring in his brain." Where does that chaos come from? There is no doubt that genes play a role in at least some forms of the disorder. Also, infants who later develop autism often undergo a period of abnormal rapid brain growth in the first year of life, which may be related to an overproduction of cells that carry nerve impulses in the brain's white matter.
When the brain is "divided" into sections that are unable to communicate between each other, the results is a "divided self" that also struggles. When the wiring between the Exner and Broca is disrupted, one of the many possible outcomes might be the experiences some autistics describe. In Tito's case, there is an "overload" effect that causes "static" when we look at brain imaging. Imagine two or three radio stations too close together on the dial. You always hear a trace of those other stations overlapping the station you want to hear.
The only way we will know for certain how much this neurological difference contributes to autism(s) is to study many, many more individuals with autism diagnoses.