Friday, September 15, 2006

Culture Shapes Arithmetic in the Brain

A collaborative study by Chinese and American authors has suggested that our mother tongue might influence the development of the brain circuits involved in processing numbers and arithmetic. They used Arabic digits (a symbol system shared by both languages, rather than phonological or orthographic symbols) to present simple problems (as in 3 + 4 = ?). Using functional MRI, they demonstrated a differential cortical representation of numbers between native Chinese and English speakers (NCS and NES). Contrasting to native English speakers, who largely employ a language process that relies on the left perisylvian cortices for mental calculation such as a simple addition task, native Chinese speakers, instead, engage a visuo-premotor association network for the same task.

"Remarkable differences between NES and NCS were found during the condition of Number representation, especially in the left hemisphere ( B and D). The activation in NES is greater in the left SMA, Broca area, and Wernicke area (Wn), compared with the corresponding areas in NCS. Meanwhile, the occipito-parietal pathway, sensorimotor areas (including the cerebellum), as well as the frontal cortex, show a similar level of activation for both NCS and NES during the Number condition, which is congruent with the suggestion that the classical number-processing model involves verbal, analogue, and visual components. Importantly, much larger brain activation was found at a region in-between BA6, BA8, and BA9 in NCS. We termed this region as a premotor association area (PMA), which has been previously associated with visuo-spatial processing and various functions more closely related to cognitive than to motor processes in humans and nonhuman primates as well."

The authors note that, in addition to mother tongue, it is possible that different teaching methods across cultures, or variations in genetic disposition, could also prime the brains of Chinese and English speakers to solve mathematical equations in different ways.

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