Listening to a book likely stimulates the same cognitive and emotional parts of the brain as reading it, new research shows.
Neuroscientists created interactive maps that can predict where different categories of words activate the brain. Their latest map is focused on what happens in the brain when you read stories.
The findings, appearing today in the Journal of Neuroscience, provide further evidence that different people share similar semantic—or word-meaning—topography, opening yet another door to our inner thoughts and narratives. They also have practical implications for learning and for speech disorders, from dyslexia to aphasia.
“At a time when more people are absorbing information via audiobooks, podcasts, and even audio texts, our study shows that, whether they’re listening to or reading the same materials, they are processing semantic information similarly,” says study lead author Fatma Deniz, a postdoctoral researcher in neuroscience in the Gallant Lab at University of California, Berkeley and former fellow with the Berkeley Institute for Data Science.
Podcasts and transcripts
For this latest brain mapping study, people listened to stories from “The Moth Radio Hour,” a popular podcast series, and then read those same stories. Using functional MRI, researchers scanned their brains in both the listening and reading conditions, compared their listening-versus-reading brain activity data, and found the maps they created from both datasets were virtually identical.
The results are visible in an interactive, 3D, color-coded map, where words—grouped in such categories as visual, tactile, numeric, locational, violent, mental, emotional, and social—are presented like vibrant butterflies on flattened cortices. The cortex is the coiled surface layer of gray matter of the cerebrum that coordinates sensory and motor information.
The interactive 3D brain viewer will go online this week.
Dyslexia and other disorders
As for clinical applications, the maps could compare language processing in healthy people and in those with stroke, epilepsy, and brain injuries that impair speech. Understanding such differences can aid recovery efforts, Deniz says.
The semantic maps can also inform interventions for dyslexia, a widespread, neurodevelopmental language-processing disorder that impairs reading.
“If, in the future, we find that the dyslexic brain has rich semantic language representation when listening to an audiobook or other recording, that could bring more audio materials into the classroom,” Deniz says.
And the same goes for auditory processing disorders, in which people cannot distinguish the sounds or “phonemes” that make up words. “It would be very helpful to be able to compare the listening and reading semantic maps for people with auditory processing disorder,” she says.
Podcasts on the brain map
Nine volunteers each spent a couple of hours inside functional MRI scanners, listening and then reading stories from “The Moth Radio Hour” as researchers measured their cerebral blood flow.
Their brain activity data, in both conditions, were then matched against time-coded transcriptions of the stories, the results of which were fed into a computer program that scores words according to their relationship to one another.
Using statistical modeling, researchers arranged thousands of words on maps according to their semantic relationships. Under the animals category, for example, one can find the words “bear,” “cat,” and “fish.”
The maps, which covered at least one-third of the cerebral cortex, enabled the researchers to predict with accuracy which words would activate which parts of the brain.
The results of the reading experiment came as a surprise to Deniz, who had anticipated some changes in the way readers versus listeners would process semantic information.
“We knew that a few brain regions were activated similarly when you hear a word and read the same word, but I was not expecting such strong similarities in the meaning representation across a large network of brain regions in both these sensory modalities,” Deniz says.
Her study is a follow-up to a 2016 Gallant Lab study that recorded the brain activity of seven study subjects as they listened to stories from “The Moth Radio Hour.” That online brain viewer is available here.
Future mapping of semantic information will include experiments with people who speak languages other than English, as well as with people who have language-based learning disorders, Deniz says.
Source: UC Berkeley