Metaestabilidade e plasticidade cerebral

Em uma síntese emergente na neurociência contemporânea, uma certa noção de metaestabilidade ocupaum papel central. Iniciando por situar a importação do conceito de metaestabilidade da teoria de sistemas dinâmicose da mecânica estatística de redes complexas para essa síntese teórica na neurociência, buscamos uma aproximaçãocom a formação do conceito de plasticidade cerebral na obra de Catherine Malabou. Em seguida, exploramos algumasdas consequências de uma nova ficção ou relato neurocientífico, baseado nessa síntese e proposto principalmente porKarl Friston. Esse relato inclui, além das noções de metaestabilidade e plasticidade, uma tentativa de fundamentaçãoneurobiológica de concepções metapsicológicas a partir da dinâmica de redes neurais. Essa ficção é, por fim, desenroladanuma analogia dos processos demenciais com a intrusão, desde dentro, de processos de individuação física

Beyond the target area: an integrative view of tDCS-induced motor cortex modulation in patients and athletes

Transcranial Direct Current Stimulation (tDCS) is a non-invasive technique used to modulate neural tissue. Neuromodulation apparently improves cognitive functions in several neurologic diseases treatment and sports performance. In this study, we present a comprehensive, integrative review of tDCS for motor rehabilitation and motor learning in healthy individuals, athletes and multiple neurologic and neuropsychiatric conditions. We also report on neuromodulation mechanisms, main applications, current knowledge including areas such as language, embodied cognition, functional and social aspects, and future directions. We present the use and perspectives of new developments in tDCS technology, namely high-definition tDCS (HD-tDCS) which promises to overcome one of the main tDCS limitation (i.e., low focality) and its application for neurological disease, pain relief, and motor learning/rehabilitation. Finally, we provided information regarding the Transcutaneous Spinal Direct Current Stimulation (tsDCS) in clinical applications, Cerebellar tDCS (ctDCS) and its influence on motor learning, and TMS combined with electroencephalography (EEG) as a tool to evaluate tDCS effects on brain function161CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP465686/2014-1Não tem2014/50909-8; 13/10187–0; 14/10134–7The authors thank the Ministry of Education (MEC), FAPESP - São Paulo Research Foundation, Universidade Estadual de Londrina, Universidade Federal do Rio Grande do Norte and Universidade Federal do ABC for its support. Postdoctoral scholarships to DGSM from the Coordination for the Improvement of Higher Education Personnel (CAPES). Source(s) of financial support: This study was partially funded by grants to MB from NIH (NIH-NIMH 1R01MH111896, NIH-NINDS 1R01NS101362, NIH-NCI U54CA137788/U54CA132378, R03 NS054783) and New York State Department of Health (NYS DOH, DOH01-C31291GG), CEPID/BRAINN - The Brazilian Institute of Neuroscience and Neurotechnology (Process: 13/07559–3) to LML, Brazilian National Research Council (CNPq, Grant # 465686/2014-1) and the São Paulo Research Foundation (Grant # 2014/50909-8) to MSC, and Postdoctoral scholarships to AHO from FAPESP - Sao Paulo Research Foundation (Process: 13/10187–0 and 14/10134–7

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

Nonlinear estimation of neural processing time from BOLD signal with application to decision-making

The extraction of information about neural activity timing from BOLD signal is a challenging task as the shape of the BOLD curve does not directly reflect the temporal characteristics of electrical activity of neurons. In this work, we introduce the concept of neural processing time (NPT) as a parameter of the biophysical model of the hemodynamic response function (HRF). Through this new concept we aim to infer more accurately the duration of neuronal response from the highly nonlinear BOLD effect. The face validity and applicability of the concept of NPT are evaluated through simulations and analysis of experimental time series. The results of both simulation and application were compared with summary measures of HRF shape. The experiment that was analyzed consisted of a decision-making paradigm with simultaneous emotional distracters. We hypothesize that the NPT in primary sensory areas, like the fusiform gyrus, is approximately the stimulus presentation duration. On the other hand, in areas related to processing of an emotional distracter, the NPT should depend on the experimental condition. As predicted, the NPT in fusiform gyrus is close to the stimulus duration and the NPT in dorsal anterior cingulate gyrus depends on the presence of an emotional distracter. Interestingly, the NPT in right but not left dorsal lateral prefrontal cortex depends on the stimulus emotional content. The summary measures of HRF obtained by a standard approach did not detect the variations observed in the NPT. Hum Brain Mapp, 2012. (C) 2010 Wiley Periodicals, Inc.FAPESPFAPESPCAPESCAPESCNPq (Brazil)CNPq, Brazi

Association between abnormal brain functional connectivity in children and psychopathology: A study based on graph theory and machine learning

Objectives: One of the major challenges facing psychiatry is how to incorporate biological measures in the classification of mental health disorders. Many of these disorders affect brain development and its connectivity.In this study, we propose a novel method for assessing brain networks based on the combination of a graph theory measure (eigenvector centrality) and a one-class support vector machine (OC-SVM).Methods: We applied this approach to resting-state fMRI data from 622 children and adolescents. Eigenvector centrality (EVC) of nodes from positive- and negative-task networks were extracted from each subject and used as input to an OC-SVM to label individual brain networks as typical or atypical. We hypothesised that classification of these subjects regarding the pattern of brain connectivity would predict the level of psychopathology.Results: Subjects with atypical brain network organisation had higher levels of psychopathology (p<0.001). There was a greater EVC in the typical group at the bilateral posterior cingulate and bilateral posterior temporal corticesand significant decreases in EVC at left temporal pole.Conclusions: The combination of graph theory methods and an OC-SVM is a promising method to characterise neurodevelopment, and may be useful to understand the deviations leading to mental disorders.Sao Paulo Research Foundation - FAPESP [2013/10498-6, 2013/00506-1, 2013/08531-5]CAPESCNPq, BrazilCNPq [573974/2008-0]FAPESP [2008/57896-8, 2013/16864-4]CAPES-BrazilCAPES/FAPERGSUniv Fed ABC, Ctr Math Computat & Cognit, Santo Andre, BrazilUniv Fed Sao Paulo UNIFESP, Interdisciplinary Lab Clin Neurosci LiNC, Dept Psychiat, Sao Paulo, BrazilUniv Sao Paulo, Sch Med, Dept Radiol, Sao Paulo, BrazilCNPq, Natl Inst Dev Psychiat Children & Adolescents, Brasilia, DF, BrazilUniv Fed Rio Grande do Sul, Hosp Clin Porto Alegre, Porto Alegre, RS, BrazilUniv Fed Rio Grande do Sul, Dept Psychiat, Porto Alegre, RS, BrazilKings Coll London, Inst Psychiat, Dept Psychosis Studies, London, EnglandUniv Sao Paulo, Inst Math & Stat, Bioinformat Program, Sao Paulo, BrazilUniv Sao Paulo, Sch Med, Dept Psychiat, Sao Paulo, BrazilUniv Sao Paulo, Fac Med, Inst Radiol InRad, Sao Paulo, BrazilUniv Fed Sao Paulo UNIFESP, Interdisciplinary Lab Clin Neurosci LiNC, Dept Psychiat, Sao Paulo, BrazilFAPESP [2013/10498-6, 2013/00506-1, 2013/08531-5]CAPESCNPq, BrazilCNPq [573974/2008-0]FAPESP [2008/57896-8, 2013/16864-4]Web of Scienc