Symposium Takes a Fresh Look at Language
By Sharon Ricks
On the Front Page...
Do brains learn like lungs breathe and hearts pump blood? How do you know that you can "fasten" and "unfasten" but not "hug" and "unhug?" How does your brain accomplish syntactic processing?
New Perspectives in Language Research, a symposium series, took a new look at the neural and computational bases of language recently. Speakers were Dr. Elizabeth Bates of the University of California, San Diego; Dr. David Caplan of Massachusetts General Hospital; and Dr. Mark S. Seidenberg of the University of Southern California.
Seidenberg challenged the standard view that language involves grammar and that grammar is unlike other aspects of human knowledge. He presented an approach to language that involved forms of knowledge representation, learning and processing that are not specific to language; rather they are general capacities that underlie many aspects of cognition.
"The standard view is that language learning is possible because children are born with knowledge of the universal properties of grammar," he said. "This idea is inconsistent with facts about brain organization and development. It leaves unexplained how the child actually converges on the grammar of his or her language and doesn't provide a productive framework for thinking about how language is used."
Caplan, a professor of neurology at Harvard Medical School, discussed brain functional imaging studies of syntactic processing. He presented PET scans of studies that asked younger and older right-handed, proficient males and females to do plausibility judgment tasks. For example, volunteers were asked whether certain statements make sense, such as, "It was the tenant that irritated the leak," or "The child spilled the juice that stained the rug." He contrasted blood flow when the sentences were syntactically more complex with blood flow when they were less complex. The scans show that, during these tasks, blood flow increased in the Broca and medial inferior lateral frontal regions of the brain in proficient persons. He then presented PET scans of studies asking younger and older, right-handed, nonproficient males and females to do the same task. Surprisingly, these scans showed an increased blood flow in a different region of the brain, the superior and inferior parietal lobe and the medial frontal lobe. Other brain regions, especially medial frontal structures, were also often activated in all groups of subjects. The results suggest a specialization within the brain for one aspect of syntactic processing, and variability in that regional specialization depending on the degree of proficiency in the task.
Speaking on the brain and language in children and adults, Bates, a professor of psychology and of cognitive science, argued that grammar or language resides not only in the Broca region of the brain, but is broadly distributed throughout the brain. She presented studies involving cross-linguistic grammaticality judgment scores in individuals with a language disorder called Broca's aphasia.
She found these individuals are better at catching word order errors than agreement errors and that those abilities differ with different languages having different rules. For example, English-speaking aphasics are better than Italian-speaking aphasics at noticing word order violations; Italian-speaking aphasics are better than English-speaking aphasics in noticing agreement errors. The point? Even when the Broca region is damaged, some language ability is preserved. When studying the brain and language in children and adults, Bates urged listeners to move beyond a phrenological framework that asserts each of the mental faculties is located in a definite part of the cerebral cortex.
Her presentation also emphasized the plasticity of the brain and noted as evidence for plasticity how well children learn language despite early lesions that damage or destroy what are thought to be the "language areas" of the brain.
"We are born with a richly articulated brain," she said. "Brains learn like lungs breathe and hearts pump blood. Language is a distributed dynamic skill system overlaid on a sensory motor brain that evolved for many things."
The next seminar, "Developmental Disorders and Language," on Mar. 29, 2001, will focus on autism, William's syndrome and specific language impairment in children. The seminar series is hosted by NIDCD, NINDS, NIMH, NICHD and NIA. For more information, contact Dr. Judith Cooper, 496-5061.
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