Studies show beneficial effects of bilingual learning
How computer programs help children overcome language problems and the effect of estrogen
Scientists continue to unravel the mystery of the brain’s role in the development of language skills — and with some provocative results. One new study in this area, for example, reveals that children raised bilingually may actually be “smarter” than their monolingual peers. Other studies show how two computer learning programs potentially help children overcome reading and speech problems — results that offer hope to families who have children with learning disabilities. Dyslexia alone affects one in five school-aged children.
In addition, researchers have recently discovered an unlikely site for some speech and language processing — the cerebellum, once thought to be involved only in the control of movement. Yet another new study has found that the hormone estrogen has a positive influence on language skills. Both these findings may one day lead to more effective therapies for children and adults with speech and language disorders.
At Dartmouth College, researchers report that bilingual children may be “smarter” than their monolingual peers. These findings add weight to the bilingual side of the long-running argument about whether children who grow up bilingual are at an advantage compared to those who learn only one language.
“Our findings show that bilingual children can perform certain cognitive tasks more accurately than monolinguals,” says Laura-Ann Petitto, PhD. “Being bilingual can give you a cognitive edge.”
Petitto and her colleagues — post-doctoral fellow Stephanie Baker, graduate student Ioulia Kovelman, and Ellen Bialystok, PhD, of York University, Canada — compared a group of monolingual children, who spoke either French or English, to a group of bilingual children, who were learning one spoken language along with one signed language. The children in both groups were matched not only for age (4 to 6 years), but also for linguistic and memory development. The researchers tested the children’s cognitive ability with the “Simon Task,” a commonly used research tool that helps scientists determine how humans think and allocate attention. This task, which doesn’t involve language, involves having the children report whether rapidly changing computer-generated red and blue squares appear on the center, right, or left side of the screen.
The bilingual children far outperformed their monolingual peers. “We used to think that young bilingual children were disadvantaged because their language development was thought to be delayed and because learning two languages left them confused,” says Petitto. “But in this study we found this is definitely not true, and our bilingual children learning speech and sign provided us with a first-time answer as to why this might be so.” Because the bilingual children in the Dartmouth study expressed only one of their languages through their mouth, their sharper cognitive abilities could not be due to the increased motor practice and planning that comes from trying to speak two languages with only one mouth, explains Petitto. Instead, she says, the bilingual children’s enhanced cognitive skills are due to the increased computational demands of processing two different language systems.
“For example, the brain that has been trained for bilingual language must look up and attend to the meaning for, say, ‘cup’ in one language, while suppressing the meaning for ‘cup’ in the child’s other native language,” says Petitto. “This requires heightened computational analysis in the brain.”
Petitto’s laboratory is currently expanding upon these results by studying bilingual adults. Using modern brain imaging techniques, the researchers want to see where and how the brain processes two languages, and to learn whether adult bilinguals also show this cognitive advantage.
Second-grade students who have difficulty reading can significantly improve their reading skills within three months by practicing left-right movement discrimination for 5 to 10 minutes once or twice a week, according to a new study funded by the National Institutes of Health (NIH). This is the first time any study has found a training method that improves the reading skills of all types of inefficient readers.
The training method used in the study is an interactive computer game called MovingToRead (MTR), which was developed by Teri Lawton, PhD, chief executive officer of Perception Dynamics Institute (PDI) of Topanga Canyon, California. Lawton is the founder of PDI, a company that is developing this software for use in the schools that eventually will be profitable.
MTR therapy was designed to enhance the “where” motion pathway in the brain — the circuit of neurons that helps readers determine the location of letters of a word and words on a page. Some scientists believe that immature motion pathways are related to reading problems in children.
The study recruited 115 second-grade students from three elementary schools in the Santa Monica-Malibu and Los Angeles Unified School Districts. “MTR has been proven to be most effective in second-graders, who are at an age [7 years] when their brains are most receptive for learning,” says Lawton. Using the Dyslexia Determination Test (DDT), the students were identified as either “efficient” or “inefficient” readers. Both of these groups were divided into three subgroups. One subgroup of efficient and inefficient readers received MTR therapy for 5 to 10 minutes, once or twice a week, for three months. A second subgroup played another computer game—one designed to train the “what” visual pathway in the brain, which helps readers determine what type of word is being presented to them. The third subgroup received their school’s standard reading program. All groups also read for 15 minutes a day.
“We found that most children who practiced left-right movement discrimination transitioned from an inefficient to an efficient reader,” says Lawton. “They more than doubled their reading speed, while the reading speeds of the other two groups of inefficient readers barely increased.” Among the efficient readers, however, no significant difference emerged. Each subgroup of efficient readers increased its reading speed, although the children who practiced direction discrimination almost doubled their speed, whereas those in the other two groups improved by about 50 percent.
“These results indicate that reading skills are controlled by the where motion pathway in the brain,” says Lawton.
Children with language difficulties that are due to a certain kind of subtle hearing problem can significantly improve their language skills with an auditory training program, according to a new study from Louisiana State University (LSU) in New Orleans. These findings may help scientists develop a new and better way of diagnosing the hearing function of young children. The earlier that children have their hearing problems diagnosed, the greater the chance they can receive remedial treatment before their language impairment develops into a severe and lifelong handicap.
In previous studies, scientists discovered that despite passing standard hearing tests, many children have subtle abnormalities in their auditory system that cause severe language difficulties. Children with these hearing problems are unable to recognize speech sounds that follow each other in a very rapid sequence, although they are able to hear all other types of sounds. Thus, although they have “normal” hearing, they can’t understand everything that is said to them; nor can they speak normally because they pronounce words in the same way that they hear them. Some of these children have reading problems as well, and many are incorrectly diagnosed with attention deficit disorders.
Believing that it might be possible to train these children to recognize rapid speech sounds, Scientific Learning Corporation of Oakland, California, developed Fast ForWord™, a computer-based program that artificially slows down the sequences of sounds in speech as it teaches children to read. Gradually, over a period of eight weeks, the speed of the sounds is progressively increased until it resembles normal speech.
Studies by the founders of the program have shown that it can improve children’s language skills. To confirm these findings and to determine if and how the training affects the auditory system, the LSU researchers evaluated 109 children for their verbal communication skills before and after participating in the intervention. In 17 of the children, a special test called the middle latency response was conducted to evaluate several central components of the auditory system. In 49 others, the researchers specifically looked at the efferent system—the neural pathways that connect the auditory cortex to the inner ear. For children with normal hearing and language development, a right ear advantage is seen in the efferent system. Earlier studies had shown, however, that the efferent system tends not to be as functionally asymmetrical in children with language impairments.
“We found that Fast ForWord™ training does improve language skills in children with language impairments,” says Thierry Morlet, PhD. The researchers also uncovered a clue as to why these improvements were happening: The training caused changes in the way the children’s auditory systems functioned. The middle latency response changed after the training, showing improvement in the function of several central components of the auditory system. In addition, the function of the efferent system became more asymmetrical favoring a right ear advantage as in normally developing children.
“These results corroborate the fact that training of the brain is possible and that changes in the auditory system can be observed and measured as a result of training,” says Morlet. He and his colleagues plan next to determine why the auditory system fails to develop normally in some children and to find ways to improve the diagnosis and management of language impairments.
This study was partly funded by ICS Medical, a company selling hearing products, as part of their research program to develop new hearing diagnostic products.
New research from Georgetown University (GU) in Washington, D.C., and the National Institute of Aging has found that estrogen can influence the speed and accuracy of language processing in healthy, young women, perhaps by affecting the brain mechanisms that are used to form language. The results suggest that sex hormones may have a therapeutic role to play in helping people recover their speech after a stroke or brain injury.
These findings also offer insight into the basic mechanisms that underlie language processing, and provide the first evidence that sex hormones influence the processing of language in premenopausal women. Previous studies have shown that hormone therapy enhances language processing in postmenopausal women and age-matched men.
For their current study, the researchers tested 46 women; 21 were using oral contraceptives (users) and 25 were not (non-users). All were right-handed, native-English speakers. The women were tested on a number of cognitive tasks, including a language production task in which they were asked to fill in the missing past tense form of 64 different verbs. (For example: Sleep. Everyday I sleep in bed. Yesterday I ________ in bed.) Each woman was tested twice—once during the high estrogen (luteal) phase of her menstrual cycle and again during its low estrogen (follicular) phase. The researchers compared the accuracy and speed with which the users and non-users performed the language production task. They also looked at what influence the luteal and follicular phases of the women’s menstrual cycles had on their performance.
“We found that users of the pill performed better and faster than non-users,” says Ivy Estabrooke, a doctoral student at GU and lead author of the study. “We also found that all the women were faster at producing past tense forms during the follicular rather than the luteal phase of their menstrual cycle.”
Next, Estabrooke and her colleagues plan to use brain wave measurements to determine what is happening in the brain to cause estrogen’s enhancement of language processing.
New research from the Institute of Child Health, University College of London, and the University of Bristol in the UK, offers strong support to the growing evidence that the cerebellum, an area of the brain once thought to be involved only in the control of movement, also plays a role in processing speech and language. This research may one day lead to better therapeutic approaches for helping children and adults with dyslexia and other speech and language disorders.
The team of researchers studied two groups of children. In one group were 10 children with selective problems in short term phonological memory (STPM)—a facet of short-term memory that is believed to be particularly important for learning language skills, especially the learning of new words. These children had no other learning or language difficulties, although they did perform poorly on reading comprehension tasks. The other group consisted of 13 children who had been diagnosed with specific language impairment (SLI), which means they had severe difficulties with the comprehension and/or expression of language, but their non-verbal intelligence remained intact.
Both groups underwent magnetic resonance imaging (MRI) along with two control groups of healthy children matched for age, gender, and non-verbal intelligence. The researchers used a relatively new technique known as voxel-based morphometry (VBM), which enabled them to perform statistical tests on the MRI scans to detect subtle differences between brains that visual inspection alone would not have picked up.
“We found that the children with selective STPM deficits and those with SLI had less gray matter in both sides of the cerebellum compared to the children in the control groups,” says Faraneh Vargha-Khadem, PhD. “In the SLI group, this was particularly pronounced around an area of the cerebellum known as the vermis.”
These findings raise interesting questions about the role of the cerebellum in language and cognition, says Vargha-Khadem. She and her colleagues plan to next examine the relationship between phonological memory, language, and other domains of cognitive function in children diagnosed with SLI. “We want to see if we can specify the relationship between specific regions of the cerebellum and different aspects of phonological and language processing,” she says. “This knowledge would have significant implications for informing accurate diagnosis of language difficulties and could, in due course, lead to the development of appropriate rehabilitation techniques.”
Vargha-Khadem also reports on the seven-year follow-up study of the remarkable case of Alex, who, despite having the entire left hemisphere of his brain removed at age 8, has developed from about the age of 9 1/2 extraordinary speech and language skills in his right hemisphere. In about 98 percent of right-handed people, most speech and language skills are represented in the left hemisphere.
“Today, at 18, Alex’s speech and language abilities, which are entirely represented within his lone right hemisphere, are remarkably well-developed,” says Vargha-Khadem. “His speech is fluent and well-structured, and he can understand complex sentences.” Alex’s case shows, says Vargha-Khadem, that the critical period for the development of speech and language extends to age 10, and possibly beyond. It also reveals the remarkable capacity of the immature brain to reorganize speech and language functions.
Alex was born with Sturge-Weber disease (encephalotrigeminal angiomatosis), a congenital brain abnormality that often causes epileptic seizures and a developmental delay of motor and cognitive skills. As a result of this disease, Alex did not develop speech as a young child and was severely hyperactive and mentally restricted. He also had debilitating seizures. To help Alex become seizure-free, doctors removed the entire left hemisphere of his brain when he was 8:6 years old.
After his surgery, Alex’s awareness of his environment increased, and at the age of 9 years, 4 months, he started uttering his first words. His ability to speak and communicate gradually improved, and by the age of 11 he was a competent speaker.
“The level of speech and language ability that Alex produces is both qualitatively and quantitatively within the normal range and consistent with his intellectual capacity,” says Vargha-Khadem. Interestingly, she adds, functional Magnetic Resonance Imaging (fMRI) studies show that the network of language regions in Alex’s right hemisphere is similar to that used by most people in the left hemisphere.
Vargha-Khadem plans to continue to follow Alex’s progress as he proceeds into adulthood. “One of the things we hope to establish is whether functional imaging methods can help us predict reorganization of speech and language function in other children who are candidates for brain surgery,” she says.
Dawn McCoy | Society for Neuroscience