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

INTRODUCTION
Dealing with and the processing of numbers is a highly complex ability relying on
multiple cognitive representations such as numerical magnitude (Dehaene, Piazza, Pinel, &
Cohen, 2003; Hubbard, Piazza, Pinel, & Dehaene, 2005), arithmetic fact knowledge (Dehaene
et al., 2003; Delazer et al., 2003), and procedural knowledge (Butterworth, 2005; Delazer et
al., 2004). These different number representations could recently be associated with the
activation of specific neuroanatomical structures. Typically, number magnitude processing
activated the intraparietal cortex, bilaterally (e.g. Eger, Sterzer, Russ, Girald, & Kleinschmidt,
2003; Dehaene et al., 2003) while arithmetic fact knowledge was associated with activation in
the left inferior parietal cortex, in particular the left angular gyrus (Cohen, Dehaene, Chochon,
Lehéricy, & Naccache, 2000; Dehaene et al. 2003; Delazer, et al., 2003). However, when
calculation problems become more complex, apart from magnitude processing and arithmetic
fact knowledge, procedural knowledge coordinating all required processes is necessary
(Delazer et al., 2003; Semenza, 2004). It usually subsumes abilities as to select the
appropriate strategies and production rules as well as integrating all information needed to
solve the task at hand (Delazer et al., 2003). Such procedural knowledge was recently
associated with prefrontal and basal ganglia activation (Delazer et al., 2004).
To date, studies investigating the neural correlates of those different number
representations and procedural knowledge used a large variety of tasks and materials
(Chochon, Cohen, van de Mortele, & Dehaene, 1999; Cohen et al., 2000; Delazer et al., 2004;
Fullbright et al., 2000; Goebel, Johansen-Berg, Behrens, & Rushworth, 2004; Menon, Rivera,
White, Glover, & Reiss, 2000; Pinel, Dehaene, Riviére, & Le Bihan, 2001; Pinel, Piazza, Le
Bihan, & Dehaene, 2004, Simon, Mangin, Cohen, Le Bihan, & Dehaene, 2002; Stanescu-
Cosson et al., 2000; Wood, Nuerk, & Willmes, 2006). Due to this diversity of experimental
procedures and task requirements, a comparison of brain activation patterns between different
studies is very difficult. In many cases, specific numerical processing such as magnitude
176