Directed brain interactions over time: A resting-state EEG comparison between schizophrenia and healthy individuals.

Understanding the neurophysiological mechanisms of schizophrenia (SZ) is one of the challenges of neuroscience. Many anatomical and functional studies have pointed to problems in brain connectivity in SZ individuals. However, little is known about the relationships between specific brain regions and impairments in brain connectivity in SZ individuals. Herein we propose a new approach using time-varying graphs and the motif synchronization method to build dynamic brain functional networks (BFNs). Dynamic BFNs were constructed from resting-state electroencephalography (rs-EEG) of 14 schizophrenia (SZ) individuals and 14 healthy controls (HCs). BFNs were evaluated based on the percentage of synchronization importance between a pair of regions (considering external and internal interactions) over time. We found differences in the directed interaction between brain regions in SZ individuals compared to the control group. Our method revealed low bilaterally directed interactions between the temporal lobes in SZ individuals compared to HCs, indicating a potential link between altered brain connectivity and the characteristic symptoms of schizophrenia. From a clinical perspective, these results shed light on developing new therapeutic approaches targeting these specific neural interactions that are altered in individuals with SZ. This knowledge allows the application of better interventions focused on restoring or compensating for interrupted connectivity patterns.

Altered Dynamic Brain Connectivity in Individuals With Sickle Cell Disease and Chronic Pain Secondary to Hip Osteonecrosis.

Individuals with sickle cell disease (SCD) exhibit changes in static brain connectivity in rest. However, little known as chronic pain associated with hip osteonecrosis affects dynamic brain connectivity during rest and the motor imagery task. The aim of this study was to investigate the characteristics of the dynamic functional brain connectivity of individuals with SCD and chronic pain secondary to hip osteonecrosis. This is a cross-sectional study comparing the dynamic brain connectivity of healthy individuals (n = 18) with the dynamic brain connectivity of individuals with SCD and chronic pain (n = 22). Individuals with SCD and chronic pain were stratified into high- or low-intensity pain groups based on pain intensity at the time of assessment. Dynamic brain connectivity was assessed through electroencephalography in 3 stages, resting state with eyes closed, and during hip (painful for the SCD individuals) and hand (control, nonpainful) motor imagery. Average weight of the edges and full synchronization time (FST)-time required for 95% of the possible edges to appear over time during a given task-were evaluated. Regarding the average weight of the edges, individuals with SCD and high-intensity pain presented higher edge weight during hip motor imagery. The average weight of the edges correlated positively with pain intensity and depression symptoms. Individuals with SCD and chronic pain complete the cerebral network at rest more quickly (lower FST). Individuals with SCD and chronic pain/hip osteonecrosis have impaired dynamic brain network with shorter FST in rest network and more pronounced diffuse connectivity in individuals with high-intensity pain. The dynamic brain network evaluated by time-varying graphs and motif synchronization was able to identify differences between groups.

Frequência Alfa na meditação Gurdjieff / Alpha Frequency in Gurdjieff Meditation

Introdução: a meditação é uma prática que visa regular o estado mental e as emoções, podendo induzir a estados alterados de consciência. Dentre inúmeras técnicas de meditação, o trabalho proposto por George I. Gurdjieff, inclui práticas voltadas para o recolhimento da atenção e o equilíbrio entre a atividade do corpo, da mente e do sentimento. Estudos realizados com eletroencefalografia (EEG), avaliando o estado meditativo em geral, demonstraram um padrão cerebral caracterizado pelo aumento da amplitude dos ritmos eletroencefalográficos alfa e teta, bem como diferenças na atividade alfa entre a meditação e o relaxamento. Entretanto, isto não está caracterizado em meditadores da linha de G.I. Gurdjieff, que praticam, além de meditações sentadas, exercícios corporais acompanhados de uma música própria e exercícios de atenção durante a vida diária. Objetivo: comparar a atividade cerebral da frequência alfa durante os estágios de meditação e relaxamento e avaliar as diferenças entre as regiões frontal, central e occipital nesses dois estados, em meditadores experientes do grupo Gurdjieff, de Salvador-Bahia-Brasil. Metodologia: a coleta da atividade cerebral dos 8 voluntários foi realizada através do EEG. O protocolo de coleta adotado foi de 6 minutos de relaxamento e 12 minutos de meditação. Resultados: foi encontrado aumento significativo da potência alfa durante a meditação, quando comparada ao relaxamento. As regiões frontal e central não apresentaram diferenças entre si para a potência alfa, enquanto a região occipital apresentou aumento da potência alfa em comparação com as regiões frontal e central. Existe um aumento da densidade de alfa durante a meditação em todas as regiões cerebrais testadas, com maior densidade na região occipital. Conclusão: A frequência alfa comporta-se de forma diferente durante a meditação, comparada ao relaxamento, com um aumento da densidade de potência durante o estado meditativo em todas as regiões avaliadas, sendo a região occipital a que apresentou maior potência.

Introduction: meditation is a practice that aims to regulate the mental state and emotions, and can induce altered states of consciousness. Among numerous meditation techniques, the work proposed by George I. Gurdjieff, includes an attempt to balance activities from the body, the mind and the feelings. Studies conducted with electroencephalography (EEG), evaluating the meditative tate, demonstrated a brain pattern characterized by increased alpha and theta amplitude, as well as differences in alpha activity between meditation and relaxation. However, this is not characterized in Gurdjieff meditators, which practice beyond sitted meditations, body exercises with music, and attentional exercises during everyday life. Objective: comparing the brain activity of the alpha power during the meditation and relaxation stages and evaluate the differences between the frontal, central and occipital regions in these two states, in experienced meditators from the Gurdjieff group, in Salvador-Bahia-Brazil. Methodology: the data collection of the brain activity from 8 volunteers was performed by EEG. The collection protocol adopted was 6 minutes of relaxation and 12 minutes of meditation. Results: a significant increase in alpha power was found during meditation, when compared to relaxation. The frontal and central regions showed no differences between them for alpha power, while the occipital region showed an increase in alpha power compared to the frontal and central regions. Conclusion: the alpha frequency behaves differently during meditation, compared to relaxation, with an increase in alpha density during the meditative state in all evaluated regions, with the occipital region being the most potent.

Spatio-temporal correlation networks of dengue in the state of Bahia.

BACKGROUND: Dengue is a public health problem that presents complexity in its dissemination. The physical means of spreading and the dynamics of the spread between municipalities need to be analyzed to guide effective public policies to combat this problem. METHODS: This study uses timing varying graph methods (TVG) to construct a correlation network between occurrences of reported cases of dengue between cities in the state of Bahia-Brazil. The topological network indices of all cities were correlated with dengue incidence using Spearman correlation. A randomization test was used to estimate the significance value of the correlation. RESULTS: The correlation network presented a complex behavior with a heavy-tail distribution of the network edges weight. The randomization test exhibit a significant correlation (P < 0.0001) between the degree of each municipality in the network and the incidence of dengue in each municipality. CONCLUSIONS: The hypothesis of the existence of a correlation between the occurrences of reported cases of dengue between different municipalities in the state of Bahia was validated. The significant correlation between the node degree and incidence, indicates that municipalities with high incidence are also responsible for the spread of the disease in the state. The method proposed suggests a new tool in epidemiological control strategy.