sentence: It is postulated that for cultural innovations such as numbers , the brain co-opts evolutionarily older and multifunctional cortical circuits ( Hubbard et al. 2005 ; Dehaene and Cohen 2007 ) , particularly invoking fronto-parietal networks , which are repeatedly implicated for the allocation of spatial attention ( Corbetta and Shulman 2002 ) , eye movement control ( Duhamel et al. 1992 ; Colby and Goldberg 1999 ) , perceptual switching during binocular rivalry ( BR ; Lumer et al. 1998 ) , vestibular cortical processing ( Dieterich et al. 2003 ) , and numerical cognition ( Piazza et al. 2004 ; Cohen Kadosh et al. 2008 ; Knops et al. 2009 ) .