Functional Imaging of Numerical Processing in Adults and 4-y-Old Children

Department of Psychological and Brain Sciences, Duke University, Durham, North Carolina, USA.
PLoS Biology (Impact Factor: 9.34). 06/2006; 4(5):e125. DOI: 10.1371/journal.pbio.0040125
Source: PubMed


Adult humans, infants, pre-school children, and non-human animals appear to share a system of approximate numerical processing for non-symbolic stimuli such as arrays of dots or sequences of tones. Behavioral studies of adult humans implicate a link between these non-symbolic numerical abilities and symbolic numerical processing (e.g., similar distance effects in accuracy and reaction-time for arrays of dots and Arabic numerals). However, neuroimaging studies have remained inconclusive on the neural basis of this link. The intraparietal sulcus (IPS) is known to respond selectively to symbolic numerical stimuli such as Arabic numerals. Recent studies, however, have arrived at conflicting conclusions regarding the role of the IPS in processing non-symbolic, numerosity arrays in adulthood, and very little is known about the brain basis of numerical processing early in development. Addressing the question of whether there is an early-developing neural basis for abstract numerical processing is essential for understanding the cognitive origins of our uniquely human capacity for math and science. Using functional magnetic resonance imaging (fMRI) at 4-Tesla and an event-related fMRI adaptation paradigm, we found that adults showed a greater IPS response to visual arrays that deviated from standard stimuli in their number of elements, than to stimuli that deviated in local element shape. These results support previous claims that there is a neurophysiological link between non-symbolic and symbolic numerical processing in adulthood. In parallel, we tested 4-y-old children with the same fMRI adaptation paradigm as adults to determine whether the neural locus of non-symbolic numerical activity in adults shows continuity in function over development. We found that the IPS responded to numerical deviants similarly in 4-y-old children and adults. To our knowledge, this is the first evidence that the neural locus of adult numerical cognition takes form early in development, prior to sophisticated symbolic numerical experience. More broadly, this is also, to our knowledge, the first cognitive fMRI study to test healthy children as young as 4 y, providing new insights into the neurophysiology of human cognitive development.

Download full-text


Available from: Elizabeth M Brannon,
  • Source
    • "However, the precise nature of right and left IPS engagement and the mechanisms underlying developmental changes in the left IPS in the present work remain opaque; future research is required. Moreover, while previous developmental neuroimaging studies have found a shift from prefrontal regions in children to parietal regions in adults (Ansari et al., 2005; Cantlon et al., 2009; Holloway and Ansari, 2010; Kaufmann et al., 2005, 2006), the present study did not reveal a negative correlation between chronological age and signal recovery in the prefrontal cortex. While the absence of an effect is difficult to interpret, this null result may nevertheless indicate that previously observed frontal activations in number comparison tasks may not be related to developmental changes of symbolic numerical magnitude representation per se or the mapping between numerical magnitudes and their symbolic referents . "
    [Show abstract] [Hide abstract]
    ABSTRACT: The way the human brain constructs representations of numerical symbols is poorly understood. While increasing evidence from neuroimaging studies has indicated that the intraparietal sulcus (IPS) becomes increasingly specialized for symbolic numerical mag-nitude representation over developmental time, the extent to which these changes are associated with age-related differences in symbolic numerical magnitude representation or with developmental changes in non-numerical processes, such as response selection, remains to be uncovered. To address these outstanding questions we investigated devel-opmental changes in the cortical representation of symbolic numerical magnitude in 6-to 14-year-old children using a passive functional magnetic resonance imaging adapta-tion design, thereby mitigating the influence of response selection. A single-digit Arabic numeral was repeatedly presented on a computer screen and interspersed with the pre-sentation of novel digits deviating as a function of numerical ratio (smaller/larger number). Results demonstrated a correlation between age and numerical ratio in the left IPS, sug-gesting an age-related increase in the extent to which numerical symbols are represented in the left IPS. Brain activation of the right IPS was modulated by numerical ratio but did not correlate with age, indicating hemispheric differences in IPS engagement during the development of symbolic numerical representation. article under the CC BY-NC-ND license (
    Developmental Cognitive Neuroscience 12/2015; 12:61-73. DOI:10.1016/j.dcn.2014.12.001 · 3.83 Impact Factor
  • Source
    • "With age, the involvement of the left inferior parietal regions increases , decreasing the initial right bias, as shown by the same fMRI paradigm used in kindergarten children and adults (Ansari and Dhital, 2006; Cantlon et al., 2006; Rivera et al., 2005). Pinel and Dehaene (2010), studying a cohort of 209 adults, reported a significant colateralization of the posterior superior temporal sulcus activation during sentence processing and of the intraparietal sulcus activation during arithmetic. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The human infant brain is the only known machine able to master a natural language and develop explicit, symbolic, and communicable systems of knowledge that deliver rich representations of the external world. With the emergence of noninvasive brain imaging, we now have access to the unique neural machinery underlying these early accomplishments. After describing early cognitive capacities in the domains of language and number, we review recent findings that underline the strong continuity between human infants' and adults' neural architecture, with notably early hemispheric asymmetries and involvement of frontal areas. Studies of the strengths and limitations of early learning, and of brain dynamics in relation to regional maturational stages, promise to yield a better understanding of the sources of human cognitive achievements.
    Neuron 10/2015; 88(1):93-109. DOI:10.1016/j.neuron.2015.09.026 · 15.05 Impact Factor
  • Source
    • "In a typical non-symbolic numerosity comparison task, participants are presented with two arrays of items and asked to choose the array containing more dots (e.g., Cantlon et al., 2006; Piazza, 2010). These studies have suggested that processing of numerosities is innate and automatic (e.g., Cantlon et al., 2009; Coubart et al., 2014; Feigenson et al., 2004). "
    [Show abstract] [Hide abstract]
    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
Show more