Electrical brain stimulation may help dyslexic people to read

Electrically stimulating the brains of dyslexic people may help to improve their reading accuracy by restoring normal patterns of rhythmic neural activity, a study carried out at the University of Geneva has found.

Dyslexia is a learning difficulty characterised by problems in recognising the different sounds that make up words and relating them to letters that causes lifelong problems with reading, writing, and spelling that affects one in ten of the UK population to some degree.

Although several possible causes have been proposed for dyslexia, the most common is what’s known as a phonological deficit - a difficulty in processing language sounds. This deficit has previously been associated with changes in rhythmic or repetitive patterns of neural activity, specifically in the so-called "low-gamma" oscillations found in a sound-processing region of the brain called left auditory cortex that typically oscillate at 30 Hz.

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To investigate this, the team applied a transcranial alternating current stimulation (tACS) over left auditory cortex of 15 adults with dyslexia and 15 fluent readers for 20 minutes. They found that the phonological processing ability and reading accuracy in the dyslexia group improved immediately, specifically when a stimulation at 30 Hz was used.

They also found that while the beneficial effect on phonological processing was most pronounced in those individuals who had poor reading skills, a slightly disruptive effect was also observed in very good readers.

The findings may pave the way to future non-invasive therapies in individuals with dyslexia or even to more permanent solutions, the team say.

“The next steps for us are to investigate whether normalizing oscillatory function in very young children could have a long-lasting effect on the organization of the reading system, but also to explore even less invasive means of correcting oscillatory activity for instance using neurofeedback training,” said lead researcher Dr Silvia Marchesotti.