When scientists study brain activity of children and adults with reading difficulties, they do not know whether the differences they see reflect a structural difference in the brain or whether they are seeing functional patterns that could be changed with teaching or learning. Since studies show that poor readers do not seem to use the left brain areas for phonetic processing in the same way as good readers, scientists are interested in learning whether specific types of teaching or training can change brain use patterns.

A Different Pattern for Dyslexia

There are now many studies that show that children and adults with dyslexia do show changes in brain activity after receiving training geared to increase their sensitivity to phonetics. As expected, with such training, the brains of people with dyslexia begin to look more like the brains of good readers, at least when performing tasks such as identifying rhyming patterns in listening to or reading words. However, it is not clear whether such changes in brain activity actually promote overall improved reading skills, or carry over to contexts other than the specific tasks that have been studied.

One leading researcher, Dr. Sally Shaywitz, looked at the brains of young adults whose progress had been followed from kindergarten and whose dyslexia had been identified by their poor performance in reading skills in early childhood. Some of these young people had grown up to become capable readers, while others remained very poor readers. Surprisingly, the improved readers had a very different pattern of brain use, while the poor readers had brain patterns more closely resembling those of typical readers without dyslexia. When doing reading tasks involving making judgments about word meaning, these improved readers appeared to completely bypass the left temporal area used for phonetic decoding, relying mostly on right temporal activity and frontal activity in both hemispheres.

In another study, scientists with the National Institute of Mental Health used tests measuring blood flow in the brain to correlate brain use patterns with reading ability in subjects with and without dyslexia. After testing their subjects for reading ability with common skills tests, brain activity was measured while the subjects were reading sentences aloud. The researchers found that there was an inverse relationship of brain use, dyslexia, and reading ability. Among the group with dyslexia, increased right brain activity correlated directly with improved reading ability. This was the opposite pattern from the group without dyslexia, whose reading ability correlated with increased left hemispheric activity.

These studies suggest that in order for a person with dyslexia to learn to read, he must also learn to use different brain pathways, perhaps because his innate brain structure makes it inefficient to use the left hemispheric pathways typically associated with good reading.

Phonological Training and Brain Activity

People with dyslexia tend to have difficulty applying and using phonetic rules to decode words. As noted earlier, brain scans show that subjects with dyslexia have reduced activity in the left brain areas normally associated with reading and increased activity in right brain regions.

Using brain scans conducted before and after intensive, short-term training to improve phonetic skills, researchers have indeed observed that children and adults with dyslexia show increased levels of left brain activity after receiving such training. However, the brain scans have also shown that such training also results in higher activation of a number of regions not normally involved in phonological processing. These regions include parts of the right side of the brain that are mirror images of the typical left-sided language processing areas.

Thus, the research seems to suggest that while training can help children and adults with dyslexia use left-brain word processing areas more effectively, the person with dyslexia is still predominantly a right-brained thinker. While most children can become good readers by learning to rely mostly on left-brain thinking processes, a child with dyslexia will need to learn to harness his natural right-brain mental strengths to build reading skills.

This research may explain why it takes longer for children with dyslexia to learn to read; the process of developing and coordinating right brain thinking with the skill set needed for reading may be more complex and take many years to develop. This research also helps explain why children with dyslexia always learn best with multisensory strategies — approaches that integrate auditory, visual, and kinesthetic learning tools, and thus probably activate more brain regions simultaneously.