RETRACTED: Influence of cognitive strategies on the pattern of cortical activation during mental subtraction. A functional imaging study in human subjects (Retracted Article)

Functional magnetic resonance imaging (fMRI) at 1.5 T was used to investigate the influence of cognitive strategies on cortical activation during mental calculation. Twenty-nine right-handed subjects performed a serial subtraction of prime numbers. Even though a common corpus of brain areas was activated during this mental calculation, differences appeared between subjects in function of their spontaneous cognitive strategy. In subjects using a so called verbal strategy (n = 15), the main activation was located in the whole left dorsolateral frontal cortex with a little activation of the inferior parietal cortex. In subjects using a so called visual strategy (n = 14), a bilateral activation in the prefrontal cortex and a high activation in the left inferior parietal cortex were observed. These results demonstrate that numbers are processed through a distributed network of cortical areas, the lateralization of which is clearly influenced by subject strategy. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.