Researchers at the Carnegie Mellon University in Pittsburgh brain found 100 hours of remedial instruction increased brain activity in several areas of the brain and the neural gains were solidified during the year following instruction.

Fifth-graders -- 25 poor readers -- worked in groups of three for an hour a day with a remedial reading teacher. Brain areas were activated at near-normal levels immediately after rededication, with only a few areas still underactive. However, by the time of a follow-up scan one year later, the activation differences between good and poor readers nearly vanished.

"This study demonstrates how remedial instruction can use the plasticity of the human brain to gain an educational improvement," study senior author Marcel Just said in a statement. "Focused instruction can help underperforming brain areas to increase their proficiency."

The study findings, published in Neuropsychologia, also contradicted a common perception that dyslexia is primarily caused by visual perception difficulties of letters -- such as confusing between letters like "p" and "d." The brain imaging showed that visual difficulties accounted for 10 percent of dyslexia cases, but 70 percent had difficulty in the area of relating the visual form of a letter to its sound.