title: Contributions from specific and general factors to unique deficits: two cases of mathematics learning difficulties.
abstract: Mathematics learning difficulties are a highly comorbid and heterogeneous set of disorders linked to several dissociable mechanisms and endophenotypes. Two of these endophenotypes consist of primary deficits in number sense and verbal numerical representations. However, currently acknowledged endophenotypes are underspecified regarding the role of automatic vs. controlled information processing, and their description should be complemented. Two children with specific deficits in number sense and verbal numerical representations and normal or above-normal intelligence and preserved visuospatial cognition illustrate this point. Child H.V. exhibited deficits in number sense and fact retrieval. Child G.A. presented severe deficits in orally presented problems and transcoding tasks. A partial confirmation of the two endophenotypes that relate to the number sense and verbal processing was obtained, but a much more clear differentiation between the deficits presented by H.V. and G.A. can be reached by looking at differential impairments in modes of processing. H.V. is notably competent in the use of controlled processing but has problems with more automatic processes, such as nonsymbolic magnitude processing, speeded counting and fact retrieval. In contrast, G.A. can retrieve facts and process nonsymbolic magnitudes but exhibits severe impairment in recruiting executive functions and the concentration that is necessary to accomplish transcoding tasks and word problem solving. These results indicate that typical endophenotypes might be insufficient to describe accurately the deficits that are observed in children with mathematics learning abilities. However, by incorporating domain-specificity and modes of processing into the assessment of the endophenotypes, individual deficit profiles can be much more accurately described. This process calls for further specification of the endophenotypes in mathematics learning difficulties.
authors.affiliation: Developmental Neuropsychology Laboratory, Department of Psychology, Universidade Federal de Minas Gerais Belo Horizonte, Brazil ; Programa de Pós-graduação em Saúde da Criança e do Adolescente, Faculdade de Medicina, Universidade Federal de Minas Gerais Belo Horizonte, Brazil.
authors.forename: Vitor G
authors.initials: VG
authors.lastname: Haase
authors.affiliation: Developmental Neuropsychology Laboratory, Department of Psychology, Universidade Federal de Minas Gerais Belo Horizonte, Brazil ; Programa de Pós-graduação em Saúde da Criança e do Adolescente, Faculdade de Medicina, Universidade Federal de Minas Gerais Belo Horizonte, Brazil.
authors.forename: Annelise
authors.initials: A
authors.lastname: Júlio-Costa
authors.affiliation: Developmental Neuropsychology Laboratory, Department of Psychology, Universidade Federal de Minas Gerais Belo Horizonte, Brazil ; Programa de Pós-graduação em Saúde da Criança e do Adolescente, Faculdade de Medicina, Universidade Federal de Minas Gerais Belo Horizonte, Brazil.
authors.forename: Júlia B
authors.initials: JB
authors.lastname: Lopes-Silva
authors.affiliation: Developmental Neuropsychology Laboratory, Department of Psychology, Universidade Federal de Minas Gerais Belo Horizonte, Brazil.
authors.forename: Isabella
authors.initials: I
authors.lastname: Starling-Alves
authors.affiliation: Developmental Neuropsychology Laboratory, Department of Psychology, Universidade Federal de Minas Gerais Belo Horizonte, Brazil.
authors.forename: Andressa M
authors.initials: AM
authors.lastname: Antunes
authors.affiliation: INSERM, U992, Cognitive Neuroimaging Unit Gif sur Yvette, France ; CEA, DSV/I2BM, NeuroSpin Center Gif sur Yvette, France.
authors.forename: Pedro
authors.initials: P
authors.lastname: Pinheiro-Chagas
authors.affiliation: Department of Neuropsychology, Institute of Psychology, Karl-Franzens-University of Graz Graz, Austria.
authors.forename: Guilherme
authors.initials: G
authors.lastname: Wood
keywords: dyslexia; endophenotype; mathematics learning difficulties; number sense; phonological processing; verbal numerical representations