Basic Number Representations and their Neural Basis
Wim Fias
Universiteit Gent

In the first part of my talk I will focus on basic number representations and how they are neurally implemented. Two types of number coding can be distinguished: summation coding and number-selective coding. I will discuss the results of computational modelling and fMRI studies that show how these number representations are functionally related and integrated along an occipito-parietal network. In the second part I will focus on how these basic number representations are associated to space. It is commonly assumed that basic number representations are spatially coded as a mental number line. Access to specific number representations is supposed to be mediated by mechanisms of spatial attention. I will present evidence from neglect patients and from behavioural experiments in healthy controls that question this idea. An alternative framework is presented. It proposes that the coding of position in working memory is spatially coded and that it is these spatial codes that drive the phenomena that have been interpreted as being signatures of a mental number line.