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.

This novel approach of directly comparing healthy participants with TMS-induced virtual dyscalculia to participants suffering from developmental dyscalculia enabled the researchers to propose a direct causal relationship between malfunctions along the right intraparietal sulcus and developmental dyscalculia.

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Contact: Alex Brew
a.brew@ucl.ac.uk
44-020-767-99726
University College London
22-Mar-2007