Impaired acuity of the approximate number system in 22q11.2 microdeletion syndrome

A magnitude comparison deficit has been frequently observed in velocardiofacial syndrome (Del22q11.2). We hypothesized that this deficit extends to impairments in the acuity of the approximate number system (ANS). Three groups of children aged 8-14 years were investigated: Del22q11.2 children (n = 12), low cognitive ability children (LCA; n = 12), and matched typically developing children (TD; n = 28). All children were assessed with a simple reaction time task and symbolic and nonsymbolic number comparison tasks. To estimate the acuity of the ANS, the Weber fraction (w) was calculated from the nonsymbolic comparison task. The Del22q11.2 group exhibited a significantly higher w compared with the other groups. Importantly, no significant differences were found in w between the TD and LCA groups. The performance pattern of the Del22q11.2 group was similar to the TD group in the symbolic comparison task, and both of these groups had better performance than the LCA group. The impairment of ANS acuity observed in individuals with Del22q11.2 cannot be explained by deficits in general processing speed because no significant group differences were found in the simple reaction time task. These results suggest that lower acuity of the ANS should be added to the behavioral phenotype of Del22q11.2. The absence of impaired ANS acuity in the LCA group is consistent with the hypothesis that number sense is a relatively specific and autonomous domain. Investigations of low ANS acuity in mathematics learning difficulties and Del22q11.2 should be intensified...

School Achievement Test: normative data for a representative sample of elementary school children

The present study established norms for the spelling and arithmetic subtests of the School Achievement Test (Teste do Desempenho Escolar [TDE]) in two Brazilian cities located in the state of Minas Gerais and compared the results with those obtained from the original normative sample. A stratified proportional sample of 1,034 students from Belo Horizonte and Mariana, from the 1st to 6th grades, was selected. The participants were assessed by the spelling and arithmetic subtests of the TDE. Significant differences were found between the results from Minas Gerais and Rio Grande do Sul, with moderate to high effect sizes. Significant differences were found in percentiles and classification parameters. The educational performance of the children from Minas Gerais was generally classified as less than expected (i.e., inferior) when the original norms were used as a classification parameter. Considering the high variability of educational data in different Brazilian regions, using norms for educational assessment based on only one Brazilian region is inappropriate.

Explaining school mathematics performance from symbolic and nonsymbolic magnitude processing: similarities and differences between typical and low-achieving children

Magnitude processing is one of the most central cognitive mechanisms that underlie persistent mathematics difficulties. No consensus has yet been reached about whether these difficulties can be predominantly attributed to deficits in symbolic or nonsymbolic magnitude processing. To investigate this issue, we assessed symbolic and nonsymbolic magnitude representations in children with low or typical achievement in school mathematics. Response latencies and the distance effect were comparable between groups in both symbolic and nonsymbolic tasks. The results indicated that both typical and low achievers were able to access magnitude representation via symbolic and nonsymbolic processing. However, low achievers presented higher error rates than typical achievers, especially in the nonsymbolic task. Furthermore, measures of nonsymbolic magnitude explained individual differences in school mathematics better than measures of symbolic magnitude when considering all of the children together. When examining the groups separately, symbolic magnitude representation explained differences in school mathematics in low achievers but not in typical achievers. These results suggest that symbolic magnitude is more relevant to solving arithmetic problems when mathematics achievement is particularly low. In contrast, individual differences in nonsymbolic processing appear to be related to mathematics achievement in a more general manner.

A "Conceptual Nervous System" for multiple sclerosis

Neuropsychological diagnosis requires a structure-function correlation model or a "Conceptual Nervous System." The unpredictably variable, widespread, and multifocal nature of pathological changes in multiple sclerosis (MS) challenges the neuropsychological localizationist assumption. To be adapted to MS pathological and clinical heterogeneity, a Conceptual Nervous System should explain impairments associated with multifocal, subcortical, and white matter lesions that cause information processing slowing and working memory/executive function impairment. Our main goal in this theoretical study was to develop a Conceptual Nervous System for MS by integrating current neuropsychological conceptions of structural-functional correlations in MS with a model of conscious mental activity developed by Ernst Pöppel , based on periodic reentrant activity between cortical and subcortical structures. Neuropsychological profiles in MS can be explained by both threshold and multiple disconnection mechanisms. The Conceptual Nervous System encompasses a functional and structural model of the human brain-mind. The functional model classifies mental function into material and formal. Material/semantic functions are modularly organized, and their impairment causes classical focal neuropsychological symptoms. Multiple sclerosis preferentially impairs formal/syntactic function related to widespread patterns of activation and temporal organization. The structural model specifies the system anatomically functions. The neuropsychological adequacy of the proposed Conceptual Nervous System to MS is analyzed by comparing its predictions to results of extant meta-analytic studies

A natureza e a criação da xenofobia: uma perspectiva da neurociência cognitiva social / The nature and the nurture of xenophobia: a social cognitive neuroscience perspective

O objetivo desta revisão é integrar evidências provindas de múltiplas metodologias dentro do corpo de conhecimento das neurociências para analisar a natureza e a criação da xenofobia. Argumentaremos que a xenofobia é uma forma de atitude estereotipada, cuja natureza está associada à circuitaria do sistema límbico, especialmente à amígdala, a qual pode ser concebida como um filtro atencional-emocional que reage, de forma protetiva, frente a estímulos novos e ambíguos. Considerando a existência de mecanismos neurocognitivos envolvidos na xenofobia, defenderemos a hipótese de que atitudes xenofóbicas são, pelo menos em parte, socialmente aprendidas. Por fim, faremos uma breve reflexão acerca da epigênese do comportamento humano.

The aim of this review is to integrate evidence from multiple methodologies of neuroscience research to examine the nature and creation of xenophobia. We argue that xenophobia is a class of stereotyped attitude, whose nature is associated with the circuitry of the limbic system, especially the amygdala, which can be conceived as an emotionalattentional filter that reacts protectively to novel and ambiguous stimuli. Considering the existence of neurocognitive mechanisms involved in xenophobia, we will support the hypothesis that xenophobic attitudes could be socially learned. Finally, a brief discussion on the epigenesis of human behavior will be presented.

Um convite à neurociência cognitiva social / An invitation to social cognitive neuroscience

O artigo visa apresentar uma nova área interdisciplinar de investigação, a neurociência cognitiva social (NCS), introduzindo seus pressupostos, métodos e eventuais contribuições à compreensão científica do comportamento. Em seguida, analisaremos resultados empíricos recentes da NCS, o que nos permitirá refletir sobre a interação entre fatores genéticos (natureza) e experienciais (criação) no desenvolvimento do comportamento humano.

The paper presents a new interdisciplinary research field, called social cognitive neuroscience (SCN). Assumptions, methods and possible contributions to the scientific understanding of behavior are presented. Recent empirical results of SCN are analyzed, which will allow a reflection about the interaction between nature and nurture in the development of human behavior.