Poster D116, Monday, March 27, 8:00 – 10:00 am, Pacific Concourse
The search for the putative number form area: A meta-analysis
Darren J. Yeo1,2, Eric D. Wilkey1, Gavin R. Price1; 1Peabody College, Vanderbilt University, USA, 2Nanyang Technological University, Singapore
A recent group of studies has revealed a putative “number form area” (NFA) in the inferior temporal gyrus (ITG) that is functionally specialized for Arabic numeral processing. Those studies suggest that an NFA has eluded prior fMRI studies as it falls within a region prone to signal dropout. Yet, several prior studies had found numeral-preferential activation in the ITG, suggesting that signal dropout might only partly account for past null findings. To evaluate whether existing findings support the existence of an NFA, we conducted an activation likelihood estimation meta-analysis of 31 neuroimaging studies with varying degrees of contrast specificity. All studies selected contrasted the visually presented Arabic numerals with other meaningful symbols across a variety of tasks in healthy adults. Concordant activation was only found in the bilateral parietal and right superior frontal regions. To test whether the inclusion of contrasts that did not control for task demands could potentially mask convergence in areas with weak effects, we conducted another meta-analysis on a subset of 20 studies. Along with the frontoparietal network found initially, convergence was found in the right ITG and inferior frontal gyrus. These findings suggest some degree of evidence for an NFA, but only after controlling for task demands, and that signal loss is not the only factor underlying null findings. Given that only five studies contributed to the NFA, the functional and localization specificity of an NFA requires more empirical evidence. Our findings also suggest a task-independent role of a frontoparietal network in Arabic numeral processing.
Topic Area: PERCEPTION & ACTION: Vision