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Home > News & Events > CLA Today Archive > Spring 2004 : First Words

First Words

by Joel Hoekstra

Language and movement are governed by complex, often instinctual rules. Peter Watson's research suggests that the ability to communicate and the capacity to dance, run, or shake hands may be linked.

With apologies to Cole Porter, bees don't do it. Eels don't do it. Even educated fleas don't do it. Only human beings, of all species, can talk.

An ability to use language is perhaps the defining trait of humans in the animal kingdom. Monkeys can learn to use computers; wolves and birds can signal each other with vocalizations. But manipulating words to form audible phrases that convey our innermost thoughts, like “Let's fall in love"—that's only human.

Nonetheless, our understanding of speech and its evolution is limited. Researchers have long theorized about the historic roots and biological origins of talk, but the neurological components of speech remain somewhat mysterious. “Speech is one of the most complex of human behaviors, and the problem with studying speech is that we have no animal homologue,” says Peter J. Watson, an assistant professor in the Department of Speech-Language-Hearing Sciences.

Studying animal brains won't tell us what we need to know because animals don't talk. And neither do cadavers.

“When you study speech, you have all the complications of dealing with live human beings,” Watson says.

Six years ago, Watson got an opportunity rarely afforded speech researchers. Then a professor at Case Western Reserve University in Cleveland, he teamed up with a neurosurgeon and a neurologist who were implanting electrodes in the brains of Parkinson's patients in an effort to reduce later-stage symptoms of the disease. (The process is called “deep brain stimulation.") Subjects remained awake during the initial part of the surgical procedure so doctors could optimize the placement of the electrode, used to reduce tremors as well as minimize side effects.

“While the surgeons were determining where they wanted the permanent electrodes, they used temporary microelectrodes that could stimulate or record neuronal activity,” Watson says. “So while the patients were in this state, I was able to record the brain activity and the sounds of their voice with a computer. Because they were synchronized, we could relate certain aspects of speech to neuronal activity. That's a very rare thing.”

The results of the experiment were surprising. Each patient's words were preceded by activity in the subthalamic nucleus, a portion of the basal ganglia circuitry, indicating that it was involved in initiating speech. Prior research had linked the basal ganglia with the initiation of other complex movements, but had not tied it directly to speech.

In experiments with full sentences, Watson was able to note abrupt fluctuations in brain activity as speakers moved from subject to predicate. This suggests, he says, that the basal ganglia is involved not only with the complex sequencing of movements in the wrists, arms, and shoulders, but also with the movement required for producing speech and, specifically, with syntax.

Watson's findings could have a profound impact on how speech disorders are treated. In speech therapy, the emphasis is often on muscle movement—the shape of the lips, the movement of the jaw, and the placement of the tongue. But Watson says that exercising muscles without employing language and engaging the areas of the brain that transform language into speech may be the wrong approach.

“I believe you can't separate speech from language,” he explains. “It's not just the movement of the tongue, the jaw, or the lips. My definition of speech is that it's the acoustic representation of language.”

Asking patients with speech disorders to concentrate on muscle movements without addressing larger language problems may be like asking basketball players to execute each intricate movement related to shooting baskets without giving them a ball and asking them to do a lay-up.

In his lab at the University of Minnesota, Watson's research is informed by the data gleaned from his work with Parkinson's patients. The University offers good opportunities for collaboration, he says, both across departments and with community organizations such as the Struthers Parkinson's Center, a Golden Valley-based national treatment and research center. But Watson enjoys teaching as much as research. “In my classes, I like to break students into groups and have them answer questions cooperatively. They like it, and it often raises questions that keep me sharp as a teacher,” he says.

Not surprisingly, Watson is passionate about his field. Understanding speech, and treating the disorders that affect speech, are vital work because talk is such an important part of being human, he says: “You can tell someone that you love them, or build buildings, or put together electronic circuitry, or share a story or some of your culture. We can share with people who we are through the process of speech. Speech is that immediate reference point to our humanity.”