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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    • "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
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    • "Therefore, it is also possible that, when you are deciding which line to join in the supermarket , you are using nonnumerical magnitudes or a combination of numerical and nonnumerical magnitudes (Leibovich & Henik, 2013; Henik, Leibovich, Naparstek, Diesendruck, & Rubinsten, 2012; Mix et al., 2002). Indeed, there is evidence that both numerical (Cantlon, Libertus, et al., 2009; Nieder & Dehaene, 2009) and nonnumerical (e.g., Leibovich & Henik, 2013, 2014; Gebuis & Reynvoet, 2011; Mix et al., 2002; Clearfield & Mix, 1999) magnitudes are being processed automatically when comparing numerical magnitudes. That is, for example, when deciding which of two dot arrays is numerically larger, the task-irrelevant nonnumerical magnitudes (e.g., array, density ) influence RTs and accuracy although they are not relevant to the task. "
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    ABSTRACT: It is well established that, when comparing nonsymbolic magnitudes (e.g., dot arrays), adults can use both numerical (i.e., the number of items) and nonnumerical (density, total surface areas, etc.) magnitudes. It is less clear which of these magnitudes is more salient or processed more automatically. In this fMRI study, we used a nonsymbolic comparison task to ask if different brain areas are responsible for the automatic processing of numerical and nonnumerical magnitudes, when participants attend to either the numerical or the nonnumerical magnitudes of the same stimuli. An interaction of task (numerical vs. nonnumerical) and congruity (congruent vs. incongruent) was found in the right TPJ. Specifically, this brain region was more strongly activated during numerical processing when the nonnumerical magnitudes were negatively correlated with numerosity (incongruent trials). In contrast, such an interference effect was not evident during nonnumerical processing when the task-irrelevant numerical magnitude was incongruent. In view of the role of the right TPJ in the control of stimulus-driven attention, we argue that these data demonstrate that the processing of nonnumerical magnitudes is more automatic than that of numerical magnitudes and that, therefore, the influence of numerical and nonnumerical variables on each other is asymmetrical.
    Journal of Cognitive Neuroscience 10/2015; · 4.09 Impact Factor
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    • "The notion of numerosity as an innate and primary ability is based on studies with non-human animals (McComb et al., 1994; Nieder and Dehaene, 2009; Pisa and Agrillo, 2008), young babies and newborns (e.g., Cantlon et al., 2009; Coubart et al., 2014; Xu and Spelke, 2000) who exhibited a spontaneous ability to discriminate numerosities. These studies, however, suffered from an inherent confound. "
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    ABSTRACT: Numerical judgments are involved in almost every aspect of our daily life. They are carried out so efficiently that they are often considered to be automatic and innate. However, numerosity of non-symbolic stimuli is highly correlated with its continuous properties (e.g., density, area), and so it is hard to determine whether numerosity and continuous properties rely on the same mechanism. Here we examined the behavioral and neuronal mechanisms underlying such judgments. We scanned subjects' hemodynamic responses to a numerosity comparison task and to a surface area comparison task. In these tasks, numerical and continuous magnitudes could be either congruent or incongruent. Behaviorally, an interaction between the order of the tasks and the relevant dimension modulated the congruency effects. Continuous magnitudes always interfered with numerosity comparison. Numerosity, on the other hand, interfered with the surface area comparison only when participants began with the numerosity task. Hemodynamic activity showed that context (induced by task order) determined the neuronal pathways in which the dimensions were processed. Starting with the numerosity task led to enhanced activity in the right hemisphere, while starting with the continuous task led to enhanced left hemisphere activity. Continuous magnitudes processing relied on activation of the frontal eye field and the post-central gyrus. Processing of numerosities, on the other hand, relied on deactivation of these areas, suggesting active suppression of the continuous dimension. Accordingly, we suggest that numerosities, even in the subitizing range, are not always processed automatically; their processing depends on context and task demands. Copyright © 2015. Published by Elsevier Ltd.
    Neuropsychologia 08/2015; 77:NSYD1500289. DOI:10.1016/j.neuropsychologia.2015.08.016 · 3.30 Impact Factor
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