Visual aspects of numeracy neuroimaging: cortical surface-based meta-analysis.

INTRODUCTION: Neuroimaging research has identified regions in parietal cortex related to visual numeracy. In particular, the horizontal segment of the intraparietal sulcus (IPS) may be the site of domain-specific neural activity related to understanding numbers. Meta-analysis is invaluable for assessing reliability across studies, but it can be difficult to establish the precise cortical location of published neuroimaging coordinates that lie in deep cortical sulci like the IPS. We applied a meta-analysis technique that projects stereotaxic coordinates onto a cortical surface atlas to analyze the location of functionally significant regions across studies. METHODS: The Matlab toolbox VAMCA (Visualization And Meta-analysis on Cortical Anatomy; http:/nitrc.org/projects/vamca) uses a database of cortices from 60 healthy subjects to locate activations on a standardized cortical surface by extending the technique of multi-fiducial mapping. Here we used coordinates from over 100 published articles to examine the consistency of functional activations from numeracy tasks. We also compared differences in activation loci that corresponded to parameters that varied across studies, including cognitive demands (e.g. magnitude comparison vs. enumeration), visual displays (e.g. symbolic vs. analog depictions of numbers), and ranges of numbers (which interacts with perceptual grouping). RESULTS: Meta-analyses showed that a region in the horizontal segment of the IPS is activated during diverse kinds of number judgments. There was also evidence that symbolic (numerals) and analog (dots) representations activated relatively superior and inferior portions of the horizontal/anterior IPS. We identified subregions of occipitotemporal cortex that may respond selectively to lower (1-10) and higher (10-100) ranges. CONCLUSION: Cortical surface-based meta-analysis is useful for testing the reliability and generality of IPS effects discovered in recent numeracy neuroimaging studies. We propose that the different kinds of perceptual organization afforded by small and large sets of dots may engage lateral and inferior occipitotemporal regions, respectively, during numeracy tasks. Meeting abstract presented at VSS 2017