by Justine Alford
Photo credit: patpitchaya/ Shutterstock
Given the fact that writing is a relatively recent invention, scientists are keen to understand how we read and recognize words as our brains cannot have evolved a dedicated mechanism for reading. Clues about these abilities started to be unraveled a few years back when scientists discovered a part of the brain that was activated upon reading, but interestingly, its response seemed to be strictly visual. This led scientists to believe that we identify words from images before associating them with sounds and meanings.
Although this idea was contested, scientists have now gathered evidence that lends support to this hypothesis. According to a new study, our brain sees words we know like a picture, recognizing whole words, rather than strings of letters that require processing. By tuning neurons to respond to complete words that have been seen before, our brain allows us to read quickly.
“We are not recognizing words by quickly spelling them out or identifying parts of words, as some researchers have suggested,”
senior author Maximilian Reisenhuber explains in a statement. “Instead, neurons in a small brain area remember how the whole word looks—using what could be called a visual dictionary.”
The functional brain region Reisenhuber is referring to is called the visual word form area (VWFA). This is located in the left side of the visual cortex, roughly behind the left ear and opposite a similar region on the right side known as the fusiform face area, which is responsible for facial recognition.
“One area is selective for a whole face, allowing us to quickly recognize people,” Reisenhuber adds, “and the other is selective for a whole word, which helps us read quickly.”
To come to this conclusion, a team of scientists from Georgetown University Medical Center gathered a small group of adult participants and trained them to recognize new nonsense words, or pseudowords. In order to investigate brain activity and visualize how neurons were responding to the words, the researchers performed functional magnetic resonance imaging (fMRI) on the volunteers both before and after the learning task.
As described in the Journal of Neuroscience, they found that neurons within the VWFA respond differently to real words, like chair, than to pseudowords, such as hrica. However, they also found that activity within this region changed after learning to recognize the pseudowords. Prior to training, the pseudowords elicited broadly tuned responses, but after they learned the words, the responses became more specific and highly tuned, as if the participants were looking at real words.
“This study is the first of its kind to show how neurons change their tuning with learning words, demonstrating the brain’s plasticity,” lead author Laurie Glezer said in a news release.
Alongside furthering our knowledge of how the brain processes words, this research has implications for designing strategies to help those with reading difficulties. For example, teaching people to learn whole words as visual objects, rather than by phonetically spelling them out, could be worth investigating.