The influence of the place-value structure of the Arabic number ...

The fronto-parietal network and the intraparietal cortex
Two components of the activation of the network involving prefrontal and parietal
regions can be distinguished: First, the recruitment of general cognitive processes such as
working memory, visual attention and response selection were recurrently associated with
fronto-parietal activation. Second, specific numerical processes such as magnitude processing
(Hubbard et al., 2005) and symbolic base-10 processing (Wood et al., 2006; Hoeckner et al.,
2008; Knops, Nuerk, Sparing, Foltys, & Willmes, 2006) were found to activate a frontoparietal
network.
On the one hand, more complex mental arithmetic activates the fronto-parietal network
including the intraparietal cortex bilaterally (Kong et al., 2005). Therefore, activation within
these neural structures may reflect the deployment of instrumental resources required for
more demanding tasks (Gruber, Indefrey, Steinmetz, & Kleinschmidt, 2001). On the other
hand, recent research showed that number processing might selectively activate the
intraparietal cortex even when controlling for task complexity and response selection
demands (Ansari, Dhital, & Siong, 2006a; Ansari, Fugelsang, Dhital, & Venktraman, 2006b;
Piazz, Izard, Pinel, Le Bihan, & Dehaene, 2004). Finally, activation in the posterior superior
parietal lobule was associated with navigating upon the mental number line (Dehaene et al.
2003) and with symbolic magnitude processing (Wood et al., 2006). Since the activation
patterns found in the present study are similar to those found in the studies mentioned above,
we suggest that both, general and specific numerical, processes can be associated with
activation in the fronto-parietal network. The specific contribution of each of these processes
to the overall activation pattern will be discussed.
Magnitude processing
Stronger activation of number magnitude was observed in three contrasts: (i) when
triplets spanned a larger number range, (ii) when the distance to the mean was small
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