Representation of Number in the Brain

Department of Animal Physiology, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany.
Annual Review of Neuroscience (Impact Factor: 19.32). 04/2009; 32(1):185-208. DOI: 10.1146/annurev.neuro.051508.135550
Source: PubMed


Number symbols have allowed humans to develop superior mathematical skills that are a hallmark of technologically advanced cultures. Findings in animal cognition, developmental psychology, and anthropology indicate that these numerical skills are rooted in nonlinguistic biological primitives. Recent studies in human and nonhuman primates using a broad range of methodologies provide evidence that numerical information is represented and processed by regions of the prefrontal and posterior parietal lobes, with the intraparietal sulcus as a key node for the representation of the semantic aspect of numerical quantity.

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    • "The psychophysical functions that link numbers to subjects' estimates of numerical magnitude are both theoretically and practically important. Of theoretical interest, functions generating young children's numerical magnitude estimates have been observed in non-symbolic number discrimination of a wide range of species (for review, see Nieder and Dehaene, 2009), to change abruptly with limited experience (Opfer & Siegler, 2007; Izard & Dehaene, 2008), and to closely track abilities to deal with numbers in other contexts (Booth & Siegler, 2006; Thompson & Siegler, 2010). Thus, just as animals can better discriminate 1 and 10 objects than 101 and 110 objects, so too do children estimate magnitudes of symbols 1 and 10 to differ more than 101 and 110. "
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    ABSTRACT: Children's number-line estimation has produced a lively debate about representational change, supported by apparently incompatible data regarding descriptive adequacy of logarithmic (Opfer, Siegler, & Young, 2011) and cyclic power models (Slusser, Santiago, & Barth, 2013). To test whether methodological differences might explain discrepant findings, we created a fully crossed 2. ×. 2 design and assigned 96 children to one of four cells. In the design, we crossed anchoring (free, anchored) and sampling (over-, even-), which were candidate factors to explain discrepant findings. In three conditions (free/over-sampling, free/even-sampling, and anchored/over-sampling), the majority of children provided estimates better fit by the logarithmic than cyclic power function. In the last condition (anchored/even-sampling), the reverse was found. Results suggest that logarithmically-compressed numerical estimates do not depend on sampling, that the fit of cyclic power functions to children's estimates is likely an effect of anchors, and that a mixed log/linear model provides a useful model for both free and anchored numerical estimation.
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    • "However, if the same neurons indeed encode both 144 numerosity and motion direction, then motion direction should affect numerosity perception 145 also in the absence of adaptation. Experiment 3 (Fig. 2d) showed that the interaction between 146 motion direction and numerosity perception was also evident when subjects directly judged the 147 numerosity of coherently moving dots, without a preceding adaptation phase: Rightward 148 motion led to an overestimation of numerosity (a leftward shift of theprocessing is in the intraparietal sulcus (IPS), specifically in areas LIP and VIP (Nieder and 176Dehaene, 2009). Comparing our psychophysical results to the known numerosity tuning 177 functions of these two areas gives a first indication of where and how this cross-adaptation 178 effect may come about (Fig. 3): Because we were able to exert an adaption effect despite afiring rate with the number of items in a display (Roitman et al., 2007) and are also sensitive to motion direction (Fanini and Assad, 2009). "
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    ABSTRACT: Perception of number and space are tightly intertwined. It has been proposed that this is due to "cortical recycling", where numerosity processing takes over circuits originally processing space. Do such "recycled" circuits retain their original functionality? Here, we investigate interactions between numerosity and motion direction, two functions that both localize to parietal cortex. We describe a new phenomenon in which visual motion direction adapts nonsymbolic numerosity perception, giving rise to a repulsive aftereffect: motion to the left adapts small numbers, leading to overestimation of numerosity, while motion to the right adapts large numbers, resulting in underestimation. The reference frame of this effect is spatiotopic. Together with the tuning properties of the effect this suggests that motion direction-numerosity cross-adaptation may occur in a homolog of area LIP. "Cortical recycling" thus expands but does not obliterate the functions originally performed by the recycled circuit, allowing for shared computations across domains.
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    • "Neurological and neuropsychological clinical reports frequently mention acalculia, but specific analyses of acalculia are rather limited. Calculation ability represents an extremely complex cognitive process, which requires multifactorial processes, including verbal, spatial, memory, and executive functions [1] [2]. According to Ardila, Rosselli (2002) aphasia is an impairment of language, affecting the production or comprehension of speech and the ability to read or write. "

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