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Wednesday, September 22, 2021

Your brain on words

DEVIN McHUGH / AGGIE
DEVIN McHUGH / AGGIE

UC Davis researchers tap into brain activity when reading.

Whether studying textbooks for an exam or opening up a crisp new novel to enjoy, reading is a part of many people’s everyday lives. We learn how to read at such a young age that it almost appears surprising that so much goes into it. The science behind reading thus became a topic of interest for John Henderson, UC Davis professor of psychology and research member for the Center for Mind and Brain, who recently completed a study that examined neural mechanisms while reading.

“I’ve been interested in the cognitive processes associated with reading for a long time and recently became interested in the cognitive neuroscience of reading,” Henderson said. “So what brain processes support the component processes of reading. Things like how do we recognize words, how do we retrieve the concepts of the words we’re recognizing and how do we put it all together when we’re reading.”

The study is a notable breakthrough in the field — up until now, neuroscientists have only been able to study participants reading single words and not larger content using functional magnetic resonance imaging (fMRI). But by using a new method known as fixation-related fMRI, or FIRE fMRI, they are able to study larger processes — like reading.

“Lots of subprocesses are happening during that time,” Henderson said. “So what we wanted to do was come up with a way where we could tie the neural signal like in an fMRI experiment, to what they’re specifically attending to in the text at that moment. We tracked their eye movements while reading and we do fMRI at the same time.”

The research itself is rooted in two theories for how people understand and read words. The first theory comes out of philosophy and deep thinking, theorizing that words get their meaning by how they’re connected in a network. The second theory states that words get their meaning by what they actually refer to in the world.

To test for the understanding of words while reading, Henderson tested words based on “manipulability,” words that are concrete and manipulable versus words, like “love,” that are not as concrete. This allowed scientists to see how the brain acts in response to words that vary in how they can be manipulated.

“It turns out that when we’re reading, the more concrete the word, the more activity there is in perceptual areas and areas that have to do with motor planning and motion in the world,” Henderson said. “That really fits with the grounded cognition.”

Henderson also looked into if grammar and syntax are handled by specific neural mechanisms in the brain, or if they are handled by general purpose systems that also perform other functions. Using the same method, Henderson tested how difficult it was for subjects to read a complicated word compared to ones not as syntactically difficult.

“We find two regions, both in the left hemisphere, whereas syntactic difficulty goes up those regions show more neural activity,” Henderson said. “That suggests that those regions are specifically working on syntax and grammar.”

Research on these neural mechanisms has furthered the current understanding of how we perform processes like reading, and even confirms previous notions in the realm of cognitive neuroscience. According to Dr. Arne Ekstrom, associate professor for the UC Davis Center for Neuroscience and Department of Psychology, it also cements concepts like cognition and functional localization.

“The research supports the idea that different brain areas are involved in different aspects of cognition,” Ekstrom said. “It advances our understanding of cognition, however, by suggesting that even complex tasks, like natural reading, can still be distilled into relatively simple cognitive processes, like object identification when we see nouns.”

For students like third-year psychology major Kim Schuster, the new insights into cognitive neuroscience have sparked both interest and curiosity as to where the research will go next.

“I like the improvement in cognitive science and the insights it can give us for understanding disorders like dyslexia,” Schuster said.

As far as future directions go, Henderson still sees area for more discovery and intends to go further now that there is an understanding of how people read. For instance, are nouns and verbs treated differently when reading and if so, are other parts of speech are processed similarly? Reading development is also of interest, in order to see what changes occur over time through different stages of development.

“We also want to look at differences in the brain between people who read normally and people who have deficits,” Henderson said. “So I think the more we understand about how the brain works when we’re reading normally, the more we look to see how the brains of say dyslexic readers look when they’re trying to read.”

Written by: Alan Castillo — features@theaggie.org

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