Ansari, D. Effects of development and enculturation on number representation in the brain. Nature Rev. Neurosci. 9, 278-291

Numerical Cognition Laboratory, Department of Psychology and Graduate Program in Neuroscience, University of Western Ontario, Ontario N6G 2K3, Canada.
Nature Reviews Neuroscience (Impact Factor: 31.43). 05/2008; 9(4):278-91. DOI: 10.1038/nrn2334
Source: PubMed


A striking way in which humans differ from non-human primates is in their ability to represent numerical quantity using abstract symbols and to use these 'mental tools' to perform skills such as exact calculations. How do functional brain circuits for the symbolic representation of numerical magnitude emerge? Do neural representations of numerical magnitude change as a function of development and the learning of mental arithmetic? Current theories suggest that cultural number symbols acquire their meaning by being mapped onto non-symbolic representations of numerical magnitude. This Review provides an evaluation of this contention and proposes hypotheses to guide investigations into the neural mechanisms that constrain the acquisition of cultural representations of numerical magnitude.

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    • "These findings suggest that the ITG is influenced by activity in other brain regions with increasing task demands. Representations of numerosity in parietal and frontal brain regions are well investigated in both humans and nonhuman primates (Ansari 2008; Nieder and Dehaene 2009; Dastjerdi et al. 2013; Harvey et al. 2013; Vansteensel et al. 2014). White matter pathways connect ventral temporal cortex to these parietal and frontal regions (Yeatman et al. 2013). "
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    ABSTRACT: Recent evidence suggests that specific neuronal populations in the ventral temporal cortex show larger electrophysiological responses to visual numerals compared with morphologically similar stimuli. This study investigates how these responses change from simple reading of numerals to the active use of numerals in an arithmetic context. We recorded high-frequency broadband (HFB) signals, a reliable measure for local neuronal population activity, while 10 epilepsy patients implanted with subdural electrodes performed separate numeral reading and calculation tasks. We found that calculation increased activity in the posterior inferior temporal gyrus (ITG) with a factor of approximately 1.5 over the first 500 ms of calculation, whereas no such increase was noted for reading numerals without calculation or reading and judging memory statements. In a second experiment conducted in 2 of the same subjects, we show that HFB responses increase in a systematic manner when the single numerals were presented successively in a calculation context: The HFB response in the ITG, to the second and third numerals (i.e., b and c in a + b = c), was approximately 1.5 times larger than the responses to the first numeral (a). These results provide electrophysiological evidence for modulation of local neuronal population responses to visual stimuli based on increasing task demands.
    Cerebral Cortex 10/2015; DOI:10.1093/cercor/bhv250 · 8.67 Impact Factor
    • "Therefore, at a basic level the current findings could be seen to lend support to the hypothesis that numerical magnitude system or 'approximate number system' (ANS) is a critical foundation for the development of math competence . However, more recent evidence suggests that some degree of hemispheric lateralization may be at play in the intraparietal sulcus, whereby the left IPS is engaged by symbolic magnitude processing while the right IPS is more engaged by nonsymbolic magnitude processing (Ansari, 2008; Holloway et al., 2013; Vogel et al., 2015). In addition, a number of recent studies have suggested that symbolic magnitude processing is a stronger predictor of math skills than nonsymbolic magnitude processing (De Smedt et al., 2013). "
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    ABSTRACT: Mathematical and numerical competence is a critical foundation for individual success in modern society yet the neurobiological sources of individual differences in math competence are poorly understood. Neuroimaging research over the last decade suggests that neural mechanisms in the parietal lobe, particularly the intraparietal sulcus (IPS) are structurally aberrant in individuals with mathematical learning disabilities. However, whether those same brain regions underlie individual differences in math performance across the full range of math abilities is unknown. Furthermore, previous studies have been exclusively cross-sectional, making it unclear whether variations in the structure of the IPS are caused by or consequences of the development of math skills. The present study investigates the relation between grey matter volume across the whole brain and math competence longitudinally in a representative sample of 50 elementary school children. Results show that grey matter volume in the left IPS at the end of 1(st) grade relates to math competence a year later at the end of 2(nd) grade. Grey matter volume in this region did not change over that year, and was still correlated with math competence at the end of 2(nd) grade. These findings support the hypothesis that the IPS and its associated functions represent a critical foundation for the acquisition of mathematical competence. Copyright © 2015. Published by Elsevier Inc.
    NeuroImage 08/2015; 124(Pt A). DOI:10.1016/j.neuroimage.2015.08.046 · 6.36 Impact Factor
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    • "Searchlight methods, which span the entire brain, can overcome these limitations (Connolly et al., 2012; Devereux, Clarke, Marouchos, & Tyler, 2013; Qin et al., 2014; Rothlein & Rapp, 2014; Xue et al., 2013) and offer a powerful technique to investigate how learning and development shape neural representations across multiple brain areas. To contrast agerelated differences in VTOC areas associated with visual number form versus dorsal parietal areas associated with semantic representation of quantity (Ansari, 2008; Arsalidou & Taylor, 2011; Cohen Kadosh et al., 2008; Dehaene et al., 2003), here we also examine MRS in cytoarchitectonically-defined subdivisions of the PPC and VTOC. "
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    ABSTRACT: How the brain develops representations for abstract cognitive problems is a major unaddressed question in neuroscience. Here we tackle this fundamental question using arithmetic problem solving, a cognitive domain important for the development of mathematical reasoning. We first examined whether adults demonstrate common neural representations for addition and subtraction problems, two complementary arithmetic operations that manipulate the same quantities. We then examined how the common neural representations for the two problem types change with development. Whole-brain multivoxel representational similarity (MRS) analysis was conducted to examine common coding of addition and subtraction problems in children and adults. We found that adults exhibited significant levels of MRS between the two problem types, not only in the intra-parietal sulcus (IPS) region of the posterior parietal cortex (PPC), but also in ventral temporal-occipital, anterior temporal and dorsolateral prefrontal cortices. Relative to adults, children showed significantly reduced levels of MRS in these same regions. In contrast, no brain areas showed significantly greater MRS between problem types in children. Our findings provide novel evidence that the emergence of arithmetic problem solving skills from childhood to adulthood is characterized by maturation of common neural representations between distinct numerical operations, and involve distributed brain regions important for representing and manipulating numerical quantity. More broadly, our findings demonstrate that representational analysis provides a powerful approach for uncovering fundamental mechanisms by which children develop proficiencies that are a hallmark of human cognition. Copyright © 2015. Published by Elsevier Ltd.
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