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Magnitude processing in the brain: an fMRI study of time, space, and numerosity as a shared cortical system
Linköping University, Department of Behavioural Sciences and Learning, Psychology. Linköping University, Faculty of Arts and Sciences.
Linköping University, Department of Behavioural Sciences and Learning, Disability Research. Linköping University, Faculty of Arts and Sciences.
Linköping University, Department of Behavioural Sciences and Learning, Psychology. Linköping University, Faculty of Arts and Sciences.
2016 (English)Manuscript (preprint) (Other academic)Text
Abstract [en]

Continuous dimensions, such as time, space, and numerosity, have been suggested to be subserved by common neurocognitive mechanisms. Neuroimaging studies that have investigated either one or two dimensions simultaneously have consistently identified neural correlates in the parietal cortex of the brain. However, the degree of neural overlap across several dimensions has yet to be established, and it remains an open question whether a potential overlap can be conceptualized as a neurocognitive magnitude processing system. The current functional resonance imaging (fMRI) study investigated the potential neurocognitive overlap across three dimensions. A sample of adults (N = 24) performed three different magnitude processing tasks: a temporal discrimination task, a number discrimination task, and a line length discrimination task. A conjunction analysis revealed several overlapping neural substrates across multiple magnitude dimensions, and we argue that these cortical nodes comprise a distributed magnitude processing system. Key components of this predominantly right-lateralized system include the intraparietal sulcus, insula, premotor cortex, inferior frontal gyrus and frontal eye-fields. Together with previous research highlighting IPS, our results suggest that the insula also is a core component of the magnitude processing system. We discuss the functional role of each of these components in the magnitude processing system and suggest that further research of this system may provide insight into the etiology of neurodevelopmental disorders where cognitive deficits in magnitude processing are manifest.

Place, publisher, year, edition, pages
2016.
Keyword [en]
Number processing, Time processing, Spatial processing, Magnitude processing, Insula, Intraparietal sulcus (IPS)
National Category
Psychology Social Sciences Interdisciplinary
Identifiers
URN: urn:nbn:se:liu:diva-124667OAI: oai:DiVA.org:liu-124667DiVA: diva2:901911
Available from: 2016-02-09 Created: 2016-02-09 Last updated: 2016-02-09Bibliographically approved
In thesis
1. Magnitude Processing in Developmental Dyscalculia: A Heterogeneous Learning Disability with Different Cognitive Profiles
Open this publication in new window or tab >>Magnitude Processing in Developmental Dyscalculia: A Heterogeneous Learning Disability with Different Cognitive Profiles
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Developmental dyscalculia (DD) is a learning disability that is characterized by severe difficulties with acquiring age-appropriate mathematical skills that cannot be attributed to insufficient education, language skills, or motivation. The prevalence rate is estimated at 3-6%, meaning that a substantial portion of the population struggles to learn mathematics to such a large degree that it affects overall well-being and academic prospects. However, our understanding of the etiology of DD is incomplete and there are competing hypotheses regarding the characteristics of DD and its underlying causal factors. The purpose of the current thesis is to contribute to our understanding of DD from the perspective of cognitive psychology and cognitive neuroscience. To this end, we identify children with DD to identify the cognitive determinants of DD that hamper their ability to learn basic mathematics. It is believed that human beings are endowed with an innate ability to represent numerosities, an ability phylogenetically shared with other species. We investigate whether the purported innate number system plays a role in children with DD insofar as  failures in this system may undermine the acquisition of symbolic representations of number. Although some researchers believe DD is a monolithic learning disability that is genetic and neurobiological in origin, the empirical support for various hypotheses suggests that DD may be shaped by heterogeneous characteristics and underlying causes. The present thesis, and the studies presented therein, provides support for the notion that DD is indeed heterogeneous. We identify at least two subtypes of DD that are characterized by specific deficits in number processing, and one subtype that could more aptly be labelled as a mathematical learning disability, the causal factors of which are likely limited to deficits in non-numerical abilities. In addition, we locate candidate neurocognitive correlates that may be dysfunctional in DD.

Abstract [sv]

Dyskalkyli är en specifik inlärningssvårighet som karaktäriseras av stora svårigheter med att tillgodogöra sig matematikkunskaper som inte kan härledas till bristande undervisningsmöjligheter, språkfärdigheter, eller motivation. Prevalensen av dyskalkyli uppskattas till 3-6%, vilket innebär att en ansenlig andel av populationen har sådana besvär att lära sig matematik att det påverkar deras allmänna välbefinnande och akademiska möjligheter. Förståelsen för dyskalkyli är emellertid knapphändig, men ett flertal konkurrerande hypoteser har föreslagits avseende dess karaktäristika och kausala faktorer. Syftet med denna avhandling är att öka vår förståelse av dyskalkyli utifrån ett kognitionspsykologiskt perspektiv och utifrån kognitiv neurovetenskap. Följaktligen identifierade vi skolbarn med specifika och stora matematiksvårigheter för att sedermera undersöka vilka kognitiva faktorer som underminerar deras förmåga att förvärva grundläggande matematikfärdigheter. Rådande uppfattning är att människan är utrustad med en medfödd förmåga att uppfatta och representera antal, vilket är en förmåga som vi fylogenetiskt delar med andra arter. Vi undersöker huruvida detta medfödda antalsuppfattningssystem är involverat vid utvecklandet av dyskalkyli hos barn, där ett dysfunktionellt antalsuppfattningssystem kan underminera förmågan att tillgodogöra sig symboliska representationer av antal. Gängse uppfattning gör gällande att dyskalkyli är en enhetlig och homogen inlärningssvårighet som genetiskt och neurobiologiskt betingad. Dock har ett flertal hypoteser angående orsaken till dyskalkyli fått empiriskt stöd, vilket möjliggör tolkningen att dyskalkyli snarare är en heterogen inlärningssvårighet med olika kausala faktorer och egenskaper. Föreliggande avhandling ger stöd för denna senare tolkning. Vi identifierar åtminstone två  subtyper av dyskalkyli, som vardera karaktäriseras av specifika svårigheter med numeriska färdigheter, samt en subtyp som mer korrekt bör benämnas som matematiska inlärningssvårigheter där bidragande faktorer sannolikt kan härledas till icke-numeriska förmågor. Vidare så identifierar vi potentiella neurokognitiva korrelat som är dysfunktionella vid dyskalkyli.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2016. 94 p.
Series
Linköping Studies in Arts and Science, ISSN 0282-9800 ; 669Linköping Studies in Behavioural Science, ISSN 1654-2029 ; 195
Keyword
Developmental Dyscalculia, mathematical learning disabilities, number sense, Dyskalkyli, matematiksvårigheter, antalsuppfattning
National Category
Psychology Neurosciences
Identifiers
urn:nbn:se:liu:diva-124669 (URN)10.3384/diss.diva-124669 (DOI)978-91-7685-831-8 (Print) (ISBN)
Public defence
2016-03-11, Key 1, Hus Key, Campus Valla, Linköping, 10:00 (Swedish)
Opponent
Supervisors
Available from: 2016-02-09 Created: 2016-02-09 Last updated: 2016-02-11Bibliographically approved

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