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Saturday, April 20, 2024

A window into observing brain activity during reading


Neuroscientists combine eye-tracking methods, magnetic resonance imaging to analyze how the brain reads texts

The brain: an organ consisting of about 75 percent water and powered by sugar. The right and left hemispheres constantly communicate, allowing the human body to perform the simplest of tasks. New advancements in brain analysis bring to light neural pathways involved in human learning and understanding.

Neuroscientists have created a new observational method to study brain activity while reading texts according to a study published by UC Davis psychology professor John Henderson and colleagues in the Journal of Neuroscience.

“The purpose of the study was to find how meaning is represented in the brain, across words phrases and contexts,” said Rutvik Desai, associate professor of psychology at the University of South Carolina and co-author of the published study.

Potential long-term applications of this research could help with understanding dyslexia as well as other reading and learning disabilities.

Previous brain activity could only be recorded from subjects looking a a single phrase or sentence. Data gained from those studies were valid, but may not be an accurate portrayal of how the brain functions during natural reading.

“This new method [of utilizing many words at a time] allows us to study the brain while in context. It allows us to confirm or modify previous results,” Desai said.

People do not read just one word or a phrase at a time, but instead read complete texts such as a newspaper or magazine article. A combination of eye-tracking technology and functional magnetic resonance imaging (fMRI) was used to analyze how the brain reads longer texts.

“Eye tracking provides a rich record of what visual information the brain is selecting to process at any given time,” said Taylor Hayes, postdoctoral scholar at the UC Davis Center for Mind and Brain.

The eye tracking device, called the EyeLink 1000 Plus keeps track of which words subjects are attending to when reading.

“The EyeLink […] consists of a high-resolution camera which samples the eye image 1000 times per second (1000 Hz), and a near-infrared panel that is directed toward the eye to produce a visible reflection in the cornea called a corneal reflection,” Hayes said.

The fMRI technology measures and maps brain activity by detecting changes associated with the blood oxygenation and flow. Using only fMRI technology was problematic because it was too slow to keep up with subjects reading when more words were involved.

However, when fMRI is combined with eye-tracking technology, researchers are able to know which words subjects are looking at during any given time and see the brain activity associated with it.

“[This new] technique called fixation-related fMRI co-registers fixations with fMRI activity during scene perception and reading,” Hayes said.

Additional uses for eye-tracking technology includes research in cognitive domains such as visual search and development, as well as decision-making.

“It’s an exciting time because we have the technology and methods to study and analyze the brain,” Desai said.

Natural reading involves a variety of processes including in orthographic, visually recalling how to write words, phonological, where auditory detection of a word occurs and semantic, where processing a word happens after we hear and encode a word.

More processes are associated with natural reading such as attention and working memory. Gathering information on this subject has the potential for benefits in advancing human health.

Analyzing the brain activity behind reading and language in natural conditions remains an important but largely unexplored area.

“The knowledge that we gain from our research may help study what happens in the brain for people with Alzheimer’s or Dementia, and potentially create novel therapies,” Desai said.

In the long-term, this study has the possibility of benefitting children, helping them to absorb and learn information in the most effective way in order to succeed in school.

Neuroscience has made enormous progress in understanding one of the most complex living structures in the known universe: the human brain.

“We seek the nature of our minds. There are as many differences between minds as there are similarities. What is very interesting is the machinery of the brain and how it functions,” said Kenneth Britten, professor in the Neurobiology, Physiology and Behavior Department.

Despite advances, scientists still have yet to discover the full extent of what the brain can do.

“The bigger picture of neuroscience and our research is how the brain and mind works,” Desai said. “It is fundamentally important to all humans, across any gender or race or additional categories.”


Written by: Shivani Kamal – science@theaggie.org


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