Picture: Numbers 
For some people numbers remain a
mystery - the reason lies in the right
parietal lobe; © PixelQuelle.de

Using neuronavigated transcranial magnetic stimulation (TMS) to stimulate the brain, scientists were able to bring about dyscalculia in normal subjects for a short time while the subjects completed a maths task that involved comparing two digits, one larger in physical size than the other and the other larger numerically. For example, the subjects compared a 2 and a 4. The 2 was in a larger font than the 4 and subjects had to decide which digit was numerically larger.

The effect of TMS lasted only a few hundred milliseconds in the subjects and was brought on just at the point when the subject had to evaluate the numbers and decide which had the greater value or which was physically bigger. The test was designed to measure the subjects’ automatic processing of numbers and was rolled out to both people with the dysfunction and those without it.

The researchers found that non-dyscalculic participants displayed dyscalculic-like behaviour in number processing only during TMS-induced neuronal activity disruptions to the right intraparietal sulcus. These findings were further validated by testing participants suffering from developmental dyscalculia. The results of the dyscalculic group reproduced the behavioural results obtained in non-dyscalculic volunteers during right parietal TMS, but not after left parietal TMS or sham stimulation.

Dr Roi Cohen Kadosh, of the University College London (UCL) Institute of Cognitive Neuroscience, said: “This provides strong evidence that dyscalculia is caused by malformations in the right parietal lobe and provides solid grounds for further study on the physical abnormalities present in dyscalculics’ brains. It’s an important step to the ultimate goal of early diagnosis through analysis of neural tissue, which in turn will lead to earlier treatments and more effective remedial teaching.”

MEDICA.de; Source: University College London