Attention Deficit

A University of Arizona scientist, Thomas Christensen applied for a $1 million career development award from the National Institute of Deafness and Other Communication Disorders. The grant was awarded in April and funds Christensen to conduct a pioneering 5-year study on the roles that attention and memory play when the human brain hears and processes spoken language.

"This is the chance to study the ultimate form of animal communication – language," said Thomas A. Christensen of UA’s department of speech, language and hearing sciences (SLHS). "Humans have evolved a very sophisticated symbolic form of communication. Language affects how we think, what we believe, how we interact with each other. I’d even go so far as to say that our future as a species depends on understanding how we communicate. But very little is known about what’s going on in the brain when we’re having a simple conversation."

Christensen will use UA’s magnetic resonance imaging (MRI) facilities to map the areas and networks within the brain linked to language, attention and memory. While this has been done before, Christensen’s techniques are slightly different – inside the scanner volunteers will perform simple language discrimination tasks.

“You read in the text books is that if you’re right handed, then language is localized to the left hemisphere of your brain," Christensen said. "I found out right away – that’s just not true. Analyzing a human voice also involves the right hemisphere and even parts of the cerebellum." Nothing new here either, unfortunately.

It’s interesting that Christensen “found out right away [that language is localized to the left brain hemisphere]– that’s just not true,” because as long as 30 years ago, examinations of patients who had their corpus callosums split by accident or by surgery demonstrated language wasn’t localized in the left hemisphere of the brain.

"These MRI images destroy the myth that you’re only using about 10 percent of your brain for any particular task," Christensen said. "The crux of this grant is to learn more about the language, attention and memory centers in the brain, and also about the complex interactions between them."

The MRI scanner reveals the brain’s activity. As UA’s press release states, the MRI scanner shows networks that scientists didn’t suspect were involved when the brain listens.

"We’re getting a snapshot of what that activity is across the population. What’s so striking is how clearly we see that certain areas of the brain are strongly engaged in attentional control while other areas are not. As we scan more volunteers, we’re definitely beginning to see a pattern here."

"ADHD (Attention Deficit Hyperactivity Disorder) is probably one of the most over-diagnosed disorders of our time," Christensen said. "The reason for that, I think, is that we really don’t know very much about the biological basis of this syndrome. There’s a lot of research on it, but there’s still a lot of disagreement about what the root cause is, and about whether drugs like Ritalin that are being prescribed to children as young as 2 years old are doing any good, and if we have any business exposing our children to drugs at such a very early age," he added.

ata that show the connections among areas of the brain that are strongly engaged in language tasks, he plans to collaborate with computer modeling experts. "We could develop a mathematical model that would allow us to generate hypotheses about what we expect if we deliver a certain type of stimulus. We’d see what effect it would produce in our model."

Simulating brain activity in the mathematical model "would take the whole question of language processing beyond ‘blobology’ – where you’re just looking at blobs of activation in the brain. That’s what I hope to do," Christensen said.

So in answer to my title question, Can we map attention, memory and language links in the human brain? No. However, we do need good research in this area. MRI does demonstrate activation in areas of the brain. Christensen will have to determine the relationships between the active networks – that’s more art than science currently since current MRI and fMRI don’t depict anything more than activation. The basic tangent Christensen is examining will likely move ‘blobology’ forward a little, but we are still a long way from understanding the brain – the most complicated piece of matter that we know of. Quite a paradox, isn’t it? – the most complicated piece of matter that we know of, the brain, which is essentially a super computer, cannot understand itself. Yet.