Number-space interactions in the human parietal cortex: Enlightening the snarc effect with functional near-infrared spectroscopy

Simone Cutini, Fabio Scarpa, Pietro Scatturin, Roberto Dell'Acqua, Marco Zorzi

Research output: Contribution to journalArticlepeer-review


Interactions between numbers and space have become a major issue in cognitive neuroscience, because they suggest that numerical representations might be deeply rooted in cortical networks that also subserve spatial cognition. The spatial-numerical association of response codes (SNARC) is the most robust and widely replicated demonstration of the link between numbers and space: in magnitude comparison or parity judgments, participants' reaction times to small numbers are faster with left than right effectors, whereas the converse is found for large numbers. However, despite the massive body of research on number-space interactions, the nature of the SNARC effect remains controversial and no study to date has identified its hemodynamic correlates. Using functional near-infrared spectroscopy, we found a hemodynamic signature of the SNARC effect in the bilateral intraparietal sulcus, a core region for numerical magnitude representation, and left angular gyrus (ANG), a region implicated in verbal number processing. Activation of intraparietal sulcus was also modulated by numerical distance. Our findings point to number semantics as cognitive locus of number- space interactions, thereby revealing the intrinsic spatial nature of numerical magnitude representation. Moreover, the involvement of left ANG is consistent with the mediating role of verbal/cultural factors in shaping interactions between numbers and space.

Original languageEnglish
Pages (from-to)444-451
Number of pages8
JournalCerebral Cortex
Issue number2
Publication statusPublished - 2014


  • Functional near-infrared spectroscopy
  • Functional neuroimaging
  • Number-space interactions
  • Numerical cognition
  • SNARC effect

ASJC Scopus subject areas

  • Cognitive Neuroscience
  • Cellular and Molecular Neuroscience


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