Revisiting one of the three Rs: MRI boost for teaching phonics

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  • Published: Feb 1, 2015
  • Channels: MRI Spectroscopy
thumbnail image: Revisiting one of the three Rs: MRI boost for teaching phonics

Reading levels

Images highlight the brain regions in which multisensory subadditivity was significantly related to reading skill. In all the voxels shown in blue, children who were better readers also had lower activity for the audio-visual condition than for the auditory- and visual-only conditions. In panel A, most of the length the left-hemisphere visual object processing stream (including the VWFA) shows this relationship. In panel B, the left-hemisphere middle occipital gyrus (MOG), a region involved in identifying shapes, also shows this relationship.

The fashionability of the familiar phonics system used to teach children how to read ebbs and flows with each new era of educational enhancements. Now, a functional magnetic resonance study has demonstrated that phonics should not be overlooked in favour of alternative approaches, such as so-called whole-language techniques. Moreover, it might also be used to improve the diagnosis and treatment of common reading and learning development problems such as dyslexia.

A neuroimaging study by a team at Northwestern University, led by psychologist Chris McNorgan, now at the State University of New York at Buffalo, seems to show that phonics, a method of learning to read using word sounds, should not be ignored in favour of more conventional whole-language techniques that focus on the student memorizing word patterns. The research could lead to new and improved diagnosis and treatment of common reading disorders including dyslexia.

"Phonological information is critical for helping identify words as they're being read," explains McNorgan. He and his team used functional MRI to observe how parts of the brain respond to audio and visual word cues and publish details in the journal Brain & Language. The results suggest that a person will be a "better" reader if their visual processing is more sensitive to audio information.

How to teach reading

"There are applications here not just for reading disorders, but also for how children are taught to read in the classroom," McNorgan adds. All parts of the healthy brain are working at all times. However, different parts of the brain have their own specialized functions for particular activities. Brain imaging reveals which regions are most active, either based on blood flow or other variables, when a person does a particular task. The researchers explain that when a person reads, the Visual Word Form Area (VWFA) is excited when it encounters familiar letter combinations. Of course, most activities require communication between different parts of the brain and the processing of visual, auditory and other sensory inputs. It is not entirely clear how all these components work together to allow us to read or how they develop when we first learn to read. The McNorgan study has investigated the so-called "top-down" influence of auditory knowledge in the VWFA.

To understand the top-down influence, it is useful to picture a "bottom-up" process wherein the flow of information begins with the visual system feeding neurons that detect basic features in words such as line orientation and it is these that ultimately lead to recognition of the word. Thus, a top-down process implies that there is other information entering the system, the flow of visual recognition, that might include knowledge of the sound of a word or the syllabic parts making up that sound, the phonics, in other words.

"This auditory knowledge can be used to help rule out some letter combinations. For example, many words end in 'isk' or 'ask'. For a few milliseconds there may be some ambiguity among the neurons trying to figure out whether that last letter is a 'k' or an 'x'," explains McNorgan. "Since you don't have any words ending in 'isx' in your verbal repertoire, this helps rule out the possibility that you read the word 'disx' and instead read the word as 'disk'."

Phonics from the top-down

In order to find evidence to support this hypothesis of a top-down input, the researchers presented subjects with a wide range of reading abilities aged between 8 and 13 years with word pairs. The children had to say whether or not the pairs of words rhymed while an fMRI scanner monitored their brain activity. The experiment used three sets of conditions when presenting the word pairs: the children first read the word pairs (visual only); then they heard the word pairs (auditory only); and finally, they had a combination of sight and sound, hearing the first word but reading the second (audio-visual). The fMRI scans revealed which parts of the brain were most active during each condition.

"Looking at the voxels in a particular brain area, if the signal strengths associated with two different conditions differ, then you have some evidence that brain area processes information about the two conditions differently," explains McNorgan. To make sense of the data for all three conditions, the researchers took the sum of the auditory-only and visual-only signals and compare them to the strength of the audio-visual condition. This helped them to distinguish between multisensory sensory neurons, which become excited by audio-visual information, and collections of heterogeneous unisensory neurons, a mix of visual-only and auditory-only that respond excitedly only to one or the other input.

"If the audio-visual response is greater than the sum of the auditory-only and the visual-only, this suggests that getting both types of inputs causes these neurons to fire for longer periods of time. This is a superadditive effect," McNorgan explains. "An audio-visual response less than that sum suggests that getting both types of inputs causes these neurons to fire for less time. This is a subadditive effect."

The researchers explain that this subadditivity is associated with higher reading scores and faster responses to similarly spelled words, the reading equivalent to having a head start in a race. "As you learn how to read, your brain starts to make more use of top-down information about the sounds of letter combinations in order to recognize them as parts of words," adds McNorgan. "This information gives your word-recognition system a leg-up, allowing it to respond more quickly. The multisensory neurons are getting the job done sooner, so they don't need to fire for as long. Better readers seem to have more of these neurons taking advantage of auditory information to help the visual word recognition system along."

Specifically, the researchers say, "Skill-dependent sub-additive audiovisual modulation was found in left fusiform gyrus, extending into the putative visual word form area, and was correlated with behavioural orthographic priming."

The researchers suggest that, on the basis of their findings, early intervention and basic instruction would counterintuitively involve this auditory information, it might help some learners to think more about the sounds of different words instead of having to concentrate on recognizing particular words.

Related Links

Brain Lang, 2015, 141, 110-123: "Skill dependent audiovisual integration in the fusiform induces repetition suppression"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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