Age-effects in white matter using associated diffusion tensor imaging and magnetization transfer ratio during late childhood and early adolescence

In the last decade, several studies have described the typical brain white matter maturation in children and adolescents. Diffusion tensor imaging (DTI) is the most frequent MRI technique used to investigate the structural changes across development. However, few previous studies have used the magnetization transfer ratio (MTR), which gives a closer measure of myelin content. Here, we employed both techniques for the same sample of 176 typically developing children from 7 to 14 years of age. We investigated the associations between DTI parameters and MTR measure, to assess the myelination in the brain in development. Secondly, we investigated age-effects on DTI parameters (fractional anisotropy, axial, radial and mean diffusivities) and MTR. No significant correlations between MTR and DTI parameters were observed. In addition, a significant age-effect was detected for DTI data but was not visible for MTR data. Thereby, changes in white matter at this age might be primarily correlated with microstructural changes. (C) 2015 Elsevier Inc. All rights reserved.CAPES FoundationSao Paulo Research Foundation-FAPESPCNPq, BrazilUniv Fed Sao Paulo, Dept Psychiat, Rua Borges Lagoa 570,1 Andar, BR-04039032 Sao Paulo, BrazilFed Univ Sao Paulo UNIFESP, Interdisciplinary Lab Clin Neurosci LiNC, Sao Paulo, BrazilCNPq, Natl Inst Dev Psychiat Children & Adolescents, Sao Paulo, BrazilUniv Fed ABC, Ctr Math Computat & Cognit, Santo Andre, BrazilKings Coll London, Inst Psychiat Psychol & Neurosci, London WC2R 2LS, EnglandUniv Sao Paulo, Lab Magnet Resonance Neuroradiol, LIM 44, Inst & Dept Radiol, Sao Paulo, BrazilUniv Fed Rio Grande do Sul, Hosp Clin Porto Alegre, Dept Psychiat, BR-90046900 Porto Alegre, RS, BrazilUniv Fed Sao Paulo, Dept Psychiat, Rua Borges Lagoa 570,1 Andar, BR-04039032 Sao Paulo, BrazilFed Univ Sao Paulo UNIFESP, Interdisciplinary Lab Clin Neurosci LiNC, Sao Paulo, BrazilCAPES: 17930/12-0FAPESP: 2013/10498-6FAPESP: 2013/00506-1FAPESP: 2013/08531-5FAPESP: 2008/ 57896-8CNPq: 573974/2008-0CNPq: 442026/2014-5Web of Scienc

Connectome hubs at resting state in children and adolescents:reproducibility and psychopathological correlation

AbstractFunctional brain hubs are key integrative regions in brain networks. Recently, brain hubs identified through resting-state fMRI have emerged as interesting targets to increase understanding of the relationships between large-scale functional networks and psychopathology. However, few studies have directly addressed the replicability and consistency of the hub regions identified and their association with symptoms. Here, we used the eigenvector centrality (EVC) measure obtained from graph analysis of two large, independent population-based samples of children and adolescents (7–15 years old; total N=652; 341 subjects for site 1 and 311 for site 2) to evaluate the replicability of hub identification. Subsequently, we tested the association between replicable hub regions and psychiatric symptoms. We identified a set of hubs consisting of the anterior medial prefrontal cortex and inferior parietal lobule/intraparietal sulcus (IPL/IPS). Moreover, lower EVC values in the right IPS were associated with psychiatric symptoms in both samples. Thus, low centrality of the IPS was a replicable sign of potential vulnerability to mental disorders in children. The identification of critical and replicable hubs in functional cortical networks in children and adolescents can foster understanding of the mechanisms underlying mental disorders

Language brain dominance in patients with refractory temporal lobe epilepsy: a comparative study between functional magnetic resonance imaging and dichotic listening test Determinação de dominância cerebral para linguagem em pacientes com epilepsia refratária de lobo temporal: estudo comparativo entre ressonância magnética funcional e teste de escuta dicótica

PURPOSE: To identify brain dominance for language functions with DLT and correlate these results with those obtained from fMRI in patients suffering from intractable temporal lobe epilepsy. METHOD: This study reports on 13 patients who underwent pre-surgical epileptic evaluation between April and October 2004 at the Epilepsy Surgery Program, Hospital Sao Lucas, PUCRS. In DLT, dominance was assessed through a consonant-vowel task, whereas in fMRI patients performed a verb generation task. RESULTS: Our results identified a correlation between the fMRI lateralization index and the DLT ear predominance index and reply difference index (r=0.6, p=0.02; Pearson Correlation Coefficient), showing positive correlation between results obtained from fMRI and DLT. CONCLUSION: DLT was found to significantly correlate with fMRI. These findings indicate that DLT (a non-invasive procedure) could be a useful tool to evaluate language brain dominance in pre-surgical epileptic patients as it is cheaper to perform than fMRI.OBJETIVO: Identificar a dominância cerebral para funções de linguagem através do teste de escuta dicótica (TED) e correlacionar com os resultados de ressonância magnética funcional (RMf) em pacientes com epilepsia refratária de lobo temporal. MÉTODO: Foram estudados 13 pacientes com epilepsia refratária de lobo temporal, que realizaram avaliações pré-cirúrgicas no período de abril a outubro de 2004 no Programa de Cirurgia de Epilepsia do Hospital São Lucas da PUCRS. Realizada investigação da dominância hemisférica para linguagem através do TED Consoante-Vogal e da RMf pela geração de verbos. RESULTADOS: Verificou-se a existência de correlação entre os índices de lateralidade (RMf) e os índices de predomínio de orelha e de diferença de resposta (TED) (r=0,6, p=0,02). CONCLUSÃO: Existe correlação entre os resultados obtidos através da RMf (índice de lateralidade) e do TED (índice de predomínio de orelha e índice de diferença de resposta) em pacientes com epilepsia refratária de lobo temporal

Age effects on the default mode and control networks in typically developing children

Background: the investigation of neurodevelopment during late childhood and pre-adolescence has recently attracted a great deal of interest in the field of neuroimaging. One promising topic in this field is the formation of brain networks in healthy subjects. the integration between neural modules characterizes the ability of the network to process information globally. Although many fMRI-based neurodevelopment studies can be found in the literature, the analyses of very large samples (on the order of hundreds of subjects) that focus on the late childhood/pre-adolescence period and resting state fMRI are scarce, and most studies have focused solely on North American and European populations.Aims: in this study, we present a descriptive investigation of the developmental formation of the Default Mode Network and the Control Network based on a Brazilian, cross-sectional community sample of 447 typically developing subjects aged 7-15 years old.Methods: Resting state fMRI data were acquired using two MRI systems from the same manufacturer using the same acquisition parameters. We estimated the age effects on the strength of the links (between brain regions) and the network features (graph descriptors: degree and eigenvector centrality).Results: Our findings showed an increase in the antero-posterior connectivity in both studied networks during brain development. the graph analyses showed an increase in centrality with age for most regions in the Default Mode Network and the dorsal anterior and posterior cingulate, the right anterior insula and the left posterior temporal cortex in the Control Network.Conclusion: We conclude that the period of 7-15 years of age is crucial for the development of both the Default Mode and Control networks, with integration between the posterior and anterior neuronal modules and an increase in the centrality measures of the hub regions. (C) 2014 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Wellcome TrustUniv Fed ABC, Ctr Math Computat & Cognit, Santo Andre, BrazilUniv Fed Rio Grande do Sul, Dept Psychiat, Porto Alegre, RS, BrazilUniversidade Federal de São Paulo, LiNC, São Paulo, BrazilUniv São Paulo, Sch Med, Dept Psychiat, BR-05508 São Paulo, BrazilUniv São Paulo, Inst Math & Stat, Bioinformat Program, BR-05508 São Paulo, BrazilKings Coll London, Inst Psychiat, London, EnglandUniv São Paulo, Sch Med, Dept Radiol, BR-05508 São Paulo, BrazilCNPq, Natl Inst Dev Psychiat Children & Adolescents, Brasilia, DF, BrazilUniversidade Federal de São Paulo, LiNC, São Paulo, BrazilFAPESP: 573974/2008-0FAPESP: 2013/10498-6FAPESP: 2013/00506-1Web of Scienc

Decreased centrality of subcortical regions during the transition to adolescence:A functional connectivity study

Investigations of brain maturation processes are a key step to understand the cognitive and emotional changes of adolescence. Although structural imaging findings have delineated clear brain developmental trajectories for typically developing individuals, less is known about the functional changes of this sensitive development period. Developmental changes, such as abstract thought, complex reasoning, and emotional and inhibitory control, have been associated with more prominent cortical control. the aim of this study is to assess brain networks connectivity changes in a large sample of 7- to 15-year-old subjects, testing the hypothesis that cortical regions will present an increasing relevance in commanding the global network. Functional magnetic resonance imaging (fMRI) data were collected in a sample of 447 typically developing children from a Brazilian community sample who were submitted to a resting state acquisition protocol. the fMRI data were used to build a functional weighted graph from which eigenvector centrality (EVC) was extracted. for each brain region (a node of the graph), the age-dependent effect on EVC was statistically tested and the developmental trajectories were estimated using polynomial functions.Our findings show that angular gyrus become more central during this maturation period, while the caudate; cerebellar tonsils, pyramis, thalamus; fusiform, parahippocampal and inferior semilunar lobe become less central. in conclusion, we report a novel finding of an increasing centrality of the angular gyrus during the transition to adolescence, with a decreasing centrality of many subcortical and cerebellar regions. (C) 2014 Elsevier Inc. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Wellcome TrustUniv Fed ABC, Ctr Math Computat & Cognit, Santo Andre, BrazilUniv Fed Rio Grande do Sul, Dept Psychiat, Porto Alegre, RS, BrazilUniversidade Federal de São Paulo, Interdisciplinary Lab Clin Neurosci LiNC, UNIFESP, São Paulo, BrazilUniv São Paulo, Sch Med, Dept Psychiat, BR-05508 São Paulo, BrazilUniv São Paulo, Bioinformat Program, Inst Math & Stat, BR-05508 São Paulo, BrazilKings Coll London, Inst Psychiat, London WC2R 2LS, EnglandUniv São Paulo, Sch Med, Dept Radiol, BR-05508 São Paulo, BrazilCNPq, Natl Inst Dev Psychiat Children & Adolescents, São Paulo, BrazilUniversidade Federal de São Paulo, Interdisciplinary Lab Clin Neurosci LiNC, UNIFESP, São Paulo, BrazilFAPESP: 2013/10498-6FAPESP: 2013/00506-1CNPq: 573974/2008-0FAPESP: 2008/57896-8Web of Scienc