Reading is fundamental, but it’s also a complex skill. Now, a new study sheds more light on how the brain makes sense of the written word.

Researchers found that two key brain “networks” work in tandem to help people read sentences — so folks not only grasp the meanings of individual words but also process the bigger picture of what’s being said.

Because reading is such an essential daily activity, it’s easy to take it for granted, said study leader Oscar Woolnough, a research fellow with McGovern Medical School at UTHealth Houston.

“That is, until you lose that ability,” he said.

Woolnough pointed to the example of aphasia, which impairs people’s ability to use language — including their speech and ability to write or read. It stems from damage to the brain, often from a stroke or a head injury.

If researchers can better understand how the healthy brain allows people to read, Woolnough said, that could improve understanding of aphasia and other types of reading impairment.

For the latest study, the researchers recruited patients with epilepsy who’d had electrodes implanted in their brains to try to identify the source of their seizures.

That allowed Woolnough’s team to record the participants’ brain activity as they read — precisely charting the timing of events in a way not possible with noninvasive imaging of the brain.

Researchers had the 36 participants silently read various sentences and word lists — some composed of real words and some composed of nonsense “Jabberwocky” words (based on Lewis Carroll’s “Jabberwocky” poem).

It turned out that when people were reading real sentences, two distinct networks in the brain’s frontotemporal cortex jumped into action. In the first one, activity progressively increased as readers absorbed sentences — a ramping up not seen when people read a word list.

That, Woolnough explained, suggests the network is adding up the combined meaning of the individual words in a sentence, and building the bigger picture of what’s being said.

The second network the researchers identified worked differently: It was more active when people were reading word lists, versus sentences. But that’s not because it was lazy during sentence reading.

As Woolnough explained it, the second network seems to become more efficient when people are reading sentences — because the context of the sentence makes it easier to process the individual words.

“Your brain can start to predict what’s coming next,” he said.

The findings — published recently in the Proceedings of the National Academy of Sciences may not have any immediate implications for addressing reading disorders.

But experts said the study highlights the complexity of a task that is vital to everyday life.

Reading ability cannot be pinpointed to any one hub in the brain, said Monica McQuaid, director of the adult literacy program at Montefiore Medical Center’s Fisher Landau Center for the Treatment of Learning Disabilities in Bronx, N.Y.

Instead, it involves an orchestration of activity from various areas of the brain.

Dyslexia, for instance, sometimes gets misunderstood as a disorder where people see words “backwards,” McQuaid said. But the issue is not a visual one, she explained. It’s one of language processing.

So addressing dyslexia takes a “multi-sensory” approach, McQuaid explained. Instead of, say, just showing a child the word “cat,” a therapist can also use a picture of a cat, the recorded sound of a cat or integrate the movement of a cat — to “build meaning.”

When it comes to aphasia, people commonly think it’s a speech impairment, said Sarah Wallace, a professor of communication science and disorders at the University of Pittsburgh.

In reality, she said, aphasia impacts all language processing — speaking, writing and reading.

Like McQuaid, Wallace pointed to the array of brain areas involved in reading, and the need for “multi-faceted” approaches to managing impairments.

There are therapies to help people with aphasia improve their reading abilities, generally involving reading aloud. At the same time, Wallace said, it’s also important to make the task easier: Technology is one way to help, with text-to-speech devices that present written text and computerized speech at the same time, for example.

Technology, though, has also made everyone more reliant on reading, Wallace pointed out. Emails and text messages have replaced the old-fashioned phone call.

“Reading is such a huge part of our everyday lives,” Wallace said. “It’s part of how we make new relationships, and sustain relationships.”

So it’s “critically important,” she said, to better understand such a fundamental human ability.

More information

The American Speech-Language Hearing Association has more on aphasia.

SOURCES: Oscar Woolnough, PhD, postdoctoral research fellow, Department of Neurosurgery, McGovern Medical School at UTHealth Houston; Sarah Wallace, PhD, CCC-SLP, professor, communication science and disorders, School of Health & Rehabilitation Sciences, University of Pittsburgh; Monica McQuaid, PhD, director, Adult Literacy Program, Fisher Landau Center for the Treatment of Learning Disabilities, Children’s Evaluation and Rehabilitation Center at Montefiore, Bronx, N.Y.; Proceedings of the National Academy of Sciences, April 17, 2023, online