Scientists find the root of 'number dyslexia'
23 March 2007
Many of us find maths tricky, but for people with dyscalculia - or 'number dyslexia' - sums are truly baffling. But now scientists have discovered which part of the brain causes number mix-ups. Could the findings help dyscalculia sufferers to overcome their problem? Antenna finds out more...
Dyscalculia is a learning difficulty similar to dyslexia. But instead of having trouble with words, people with dyscalculia find numbers hard to understand, which makes counting and calculations tricky. The condition is surprisingly common. Some experts think it could affect as many as 1 in 20 people in the UK alone.
Dyscalculia can have a huge impact on people's everyday lives. If you can't understand numbers it's difficult to use money properly or tell the time. Even measuring speeds or keeping score in a game can be hard work. And for children, dyscalculia makes it hard to keep up at school.
Image: Stock.XCHNG/John evans
Until now, scientists have known little about the causes of dyscalculia, so it's been hard to help sufferers conquer their learning difficulty. Researchers thought disruptions to the brain's normal development may be partly to blame, but didn't have any evidence. Now new research has revealed the exact place in the brain where things go wrong.
Lead researcher Roi Cohen Kadosh explains how he pinpointed the trouble spot: 'First we took five normal people and put them into a brain scanner. We got them to do a simple maths task in order to see which areas of their brain were activated.'
'Next we used a technique called transcranial magnetic stimulation (TMS) to temporarily "knock out" this area of their brain. Then we tested how well they could do the maths task again. We also asked five patients with dyscalculia to do the task too.'
This volunteer is having her brain stimulated with TMS. The black coil emits a strong magnetic field, affecting the normal electrical activity of the brain.
Image: Roi Cohen Kadosh
In the task the volunteers had to say which of two numbers displayed on a screen was physically bigger, while ignoring its actual value. For instance the numbers 2 and 4 appeared together, but sometimes the 2 was bigger than the 4 and vice versa.
Image: Roi Cohen Kadosh
So what did the task show?
Before artificial brain stimulation the healthy volunteers found it difficult to ignore the numbers' value, so they were slow to sort numbers when their numerical value didn't match their size. But the dyscalculics had no such problem, finding it just as easy either way.
When a particular area of the brain called the 'right intraparietal sulcus' was knocked out, the healthy volunteers reacted to the task in the same way as those with dyscalculia, effectively bringing on the disorder.
The right intraparietal sulcus is at the back of your head near the top.
So could these results help people with dyscalculia?
'This is the first time anyone has shown a causal link between this specific brain area and dyscalculia,' says Roi Cohen Kadosh. 'In the future we hope to be able to put young children in a scanner and identify the type of dyscalculia they have, although more work is needed before we get there.'
Roi Cohen Kadosh, University College London
Image: Teodora Gliga
The researchers hope that if dyscalculia can be identified early, teachers could switch to more effective ways of coaching maths and help dyscalculic kids get back on track. But other experts aren't so sure it will be that simple.
Sue Gifford, a maths teaching expert at Roehampton University explains: 'I think it's important to realise that although many children have difficulty learning mathematics, not all of these have dyscalculia. I think that complete "number blindness" is actually really rare.'
'I think this is fascinating research, but I think dyscalculia is probably quite a complex problem. And it may not be the only reason why children exhibit maths learning difficulties. They could suffer from maths anxiety and educational problems, as well as physical difficulties associated with certain areas of the brain.'
Sue Gifford, University of Roehampton, Surrey
Image: Sue Gifford
But Roi Cohen Kadosh disagrees. 'Studies have shown that dyscalculia is more common than we thought. If we assume that only one child in every school has real dyscalculia we could risk missing cases and leave children in danger of not receiving the proper treatment.'
'Hopefully, a better understanding of the condition will lead to better identification of children with these mathematical difficulties.'