Measurements of coherence in eeg signal in brazilian people: a comparison of different consciousness states

Critically ill patients admitted to intensive care units require special care and the early diagnosis of the possible outcome of this coma is clinically important. Electroencephalographic signals are collected daily in critically ill patients and can be used to aid in the early diagnosis of neurological pathologies in such patients. Therefore, this study aimed to quantitatively describe the coherence values measured by the EEG signal of Brazilian individuals. The first group with comatose patients (N = 75), favorable (to live) or unfavorable (dying) outcomes, and various etiology. The second group was made by neurologically normal people, named the control group (N = 100). In addition, a number of statistical comparisons were made in order to verify the difference in coherence behavior according to the levels of consciousness. The coherence index of the comatose group is smaller than the control group. Besides, different hospitalization results, living or dying, as well as different etiologies, may be associated with particular values of cerebral coherence. It was observed that the etiology of coma does not influence the measured values of coherence in terms of diagnosis due to brain death, which may become a biomarker of this outcome. Another important consideration was that neurologically healthy patients did not present high values of cerebral coherence at all electrodes, as seen in the temporal region of the brain.

Electroencephalogram patterns with the presence of an unknown musical stimulus

The cerebral activity presents different behaviors in different situations and levels of consciousness, especially under musical stimulation. Signals of the central nervous system may disclose bioelectrical patterns, since listening to rhythmic sequences activates specific brain areas. In this paper, we analyze 42 neurologically normal Brazilian individuals, submitted to musical stimulation based on a procedure consisting of three different steps, during which the volunteer is kept with closed eyes. The first step is associated with the preliminary control silence period, without any stimulus, as the volunteer remains at rest. The second step consisted of unknown music stimulation. Finally, the third step involves post-music rest. Quantitative signal analysis computes the power spectrum time variations. Results point out stronger changes in gamma and high gamma waves (30 ­ 100 Hz). Even though the clinical rhythms (0 ­ 30 Hz) change throughout the whole period of the experiment, quantitative differences at gamma and high gamma bands are remarkably greater. Particularly, when comparing the initial silent period and the final post-stimulation silent one, bioelectrical differences are only highlighted by gamma and high gamma rhythms. In consequence, this paper points out that the EEG analysis of cognitive issues related to musical perception cannot disregard gamma and high gamma waves.

Frequency spectrum recurrence analysis.

In this paper, we present the new frequency spectrum recurrence analysis technique by means of electro-encephalon signals (EES) analyses. The technique is suitable for time series analysis with noise and disturbances. EES were collected, and alpha waves of the occipital region were analysed by comparing the signals from participants in two states, eyes open and eyes closed. Firstly, EES were characterized and analysed by means of techniques already known to compare with the results of the innovative technique that we present here. We verified that, standard recurrence quantification analysis by means of EES time series cannot statistically distinguish the two states. However, the new frequency spectrum recurrence quantification exhibit quantitatively whether the participants have their eyes open or closed. In sequence, new quantifiers are created for analysing the recurrence concentration on frequency bands. These analyses show that EES with similar frequency spectrum have different recurrence levels revealing different behaviours of the nervous system. The technique can be used to deepen the study on depression, stress, concentration level and other neurological issues and also can be used in any complex system.

Analysis of electroencephalography brain rhythms in the reading process.

OBJECTIVE: To verify if, by three distinct quantifiers, the measured electroencephalographic signal at rest is different from the signal measured during a word reading situation, especially considering the faster rhythms, gamma and high-gamma, as it occurs in clinical rhythms (delta to beta). METHODS: A total of 96 electroencephalographic signals measured from neurologically healthy volunteers were evaluated at two moments: resting and word reading. Each signal segment was measured by three quantifiers that separately assess normalized power, percent power, and right and left hemisphere coherence. The Mann-Whitney test was used to compare the results of the quantifiers in each brain range. RESULTS: The gamma and high-gamma rhythms presented a more distinct behavior when comparing the analyzed moments (resting and reading) than the clinical rhythms. CONCLUSION: This finding contributes to the scarce literature on faster rhythms, which can contain information that is normally disregarded in neurological clinical practice.

Analysis of electroencephalography brain rhythms in the reading process / Análise dos ritmos cerebrais de eletroencefalografia no processo de leitura

ABSTRACT Objective: To verify if, by three distinct quantifiers, the measured electroencephalographic signal at rest is different from the signal measured during a word reading situation, especially considering the faster rhythms, gamma and high-gamma, as it occurs in clinical rhythms (delta to beta). Methods: A total of 96 electroencephalographic signals measured from neurologically healthy volunteers were evaluated at two moments: resting and word reading. Each signal segment was measured by three quantifiers that separately assess normalized power, percent power, and right and left hemisphere coherence. The Mann-Whitney test was used to compare the results of the quantifiers in each brain range. Results: The gamma and high-gamma rhythms presented a more distinct behavior when comparing the analyzed moments (resting and reading) than the clinical rhythms. Conclusion: This finding contributes to the scarce literature on faster rhythms, which can contain information that is normally disregarded in neurological clinical practice.

RESUMO Objetivo: Verificar se, por meio de três quantificadores distintos, o sinal eletroencefalográfico medido em repouso é diferente do sinal medido durante o processo de leitura, especialmente considerando os ritmos rápidos, gama e supergama, assim como ocorre nos ritmos clínicos delta a beta. Métodos: Foram avaliados 96 sinais eletroencefalográficos medidos em voluntários neurologicamente saudáveis, em dois momentos: repouso e leitura de palavras. Cada trecho do sinal foi mensurado por três quantificadores que medem, de maneira isolada, a potência normalizada e a potência percentual, bem como a coerência entre os hemisférios direito e esquerdo. O teste estatístico de Mann-Whitney foi usado para comparar os resultados dos quantificadores em cada faixa cerebral. Resultados: Os ritmos gama e supergama apresentaram comportamento mais distinto entre os momentos analisados (repouso e leitura) que os ritmos clinicamente analisados. Conclusão: Esse achado contribui com a escassa literatura segundo a qual os ritmos rápidos podem conter informações que normalmente são descartadas na neurologia clínica.

Demand forecast in the emergency department in Minas Gerais, Brazil / Previsão de demanda no departamento de emergência e Minas Gerais, Brasil

This study presents a mathematical model to carry out the demand forecasts in relation to patientes classified as green in the emergency department of a municipality in Minas Gerais, Brazil. In addition, another approach will investigate whether the green patients demand remains the same over the weekend, as compared to the weekdays, since there is no support from Primary Health Care units over the weekend. A retrospective study of the emergency service in the municipality of Monte Carmelo was carried out from January 2014 to December 2017.The time series of the patients classified as green during the host by the nurse, according to the Manchester Triage Scale, was analyzed in the temporal domain for the construction of a parametric model with the purpose of realizing the demand forecast. The Manchester Triage Scale has been adopted in most emergency department as a guiding instrument for risk classification, prioritizing the most serious cases. The data processing was fulfilled using Software R Version 3.4. The ARIMA model (1,1,1)presented a better fit for this forecast. The predictions of this model are values close to those observed for the number of patients seen that ranges from 1780.4 to 1796.6 patients per month. In relation to the demand of patients classified as green at the weekend, it has shown that it is slightly lower than the weekend, but it is still an expressive demand. The application of the models must be seen by the managers as a tool to aid decisions, thus it must support processes of planning, management and evaluation of public policies. In this context, mathematical models for demand forecasting are an instrument for management care and services.

Este estudo apresenta um modelo matemático para realizar as previsões de demanda em relação aos pacientes classificados como verdes no departamento de emergência de um município de Minas Gerais. Além disso, outra abordagem investigará se a demanda dos pacientes verdes permanece a mesma no final de semana, em relação aos dias da semana, uma vez que não há apoio das unidades de Atenção Primária de Saúde no final de semana. Um estudo retrospectivo do serviço de emergência no município de Monte Carmelo foi realizado no período de janeiro de 2014 a dezembro de 2017. A série temporal dos pacientes classificados como verdes durante o acolhimento pelo enfermeiro, segundo o Sistema de Triagem de Manchester, foi analisada no domínio temporal para a construção de um modelo paramétrico com a finalidade de realizar a previsão de demanda. O Sistema de Triagem de Manchester foi adotado na maioria dos serviços de emergência como instrumento orientador para a classificação de risco, priorizando os casos mais graves. O processamento de dados foi realizado usando o Software R Versão 3.4. O modelo ARIMA (1,1,1) apresentou melhor ajuste para essa previsão. As previsões deste modelo são valores próximos aos observados para o número de pacientes atendidos que variam de 1780.4 a 1796.6 pacientes por mês. Em relação à demanda de pacientes classificados como verdes no final de semana, constatou que é ligeiramente inferior a do fim de semana, mas ainda é uma demanda expressiva. A aplicação dos modelos deve ser vista pelos gestores como uma ferramenta para auxiliar as decisões, portanto, deve apoiar processos de planejamento, gestão e avaliação de políticas públicas. Nesse contexto, os modelos matemáticos para previsão de demanda são um instrumento de atendimento e serviços gerenciais.

Magnetic, but not non-magnetic, reduced graphene oxide in spinal cord increases nociceptive neuronal responsiveness.

The interference between external magnetic fields and neurophysiology is not new, however, the role of the neuronal magnetic field remains unclear. This study aimed at investigating a possible role of the neuronal magnetic field in nociception. Highly and poorly magnetic reduced graphene oxide (rGO) was injected intrathecally in rats. Nociceptive responsiveness was greater in rats that received highly magnetic-rGO in von Frey electronic or intraplantar capsaicin tests. Furthermore, in vitro experiments demonstrated that the number of KCl-responsive DRG-neurons was greater when treated with highly magnetic-rGO when compared with non-magnetic-rGO. Our data also suggested that the mechanism underlying the increased nociceptive responsiveness involves increased Ca2+v activity. Complementary experiments excluded the cytotoxic and inflammatory effects of the magnetic-rGO in neuronal responsiveness. These data suggest that the disturbance of the neuronal magnetic field in spinal cord increases nociceptive responsiveness, suggesting an importance of the magnetic component of the electromagnetic field in neuronal transmission.

Análise do infarto do miocárdio com ênfase no supradesnivelamento do segmento ST e Escores / Myocardial infarction analysis based on ST-segment elevation and scores

Esta revisão é dedicada às principais questões relativas às alterações do segmento ST durante o infarto agudo do miocárdio (IAM), que podem ser estimadas a partir de eletrocardiograma (ECG). São discutidos o diagnóstico, o prognóstico, o tratamento e as desvantagens associadas a esta metodologia. Por fim, as principais avaliações quantitativas do IAM com base nas modificações do ECG são comparadas e discutidas no contexto dos sistemas de telemedicina.

This review focuses on the major issues regarding ST segment abnormalities during acute myocardial infarction (AMI), which may be estimated from electrocardiogram (ECG) tests. Diagnosis, prognosis, treatment and the drawbacks associated to this methodology are discussed. Finally, the major AMI quantitative assessments based on ECG deviations are compared and discussed in the context of telemedicine systems.

Quantitative Analysis of Rat Dorsal Root Ganglion Neurons Cultured on Microelectrode Arrays Based on Fluorescence Microscopy Image Processing.

Microelectrode Arrays (MEA) are devices for long term electrophysiological recording of extracellular spontaneous or evocated activities on in vitro neuron culture. This work proposes and develops a framework for quantitative and morphological analysis of neuron cultures on MEAs, by processing their corresponding images, acquired by fluorescence microscopy. The neurons are segmented from the fluorescence channel images using a combination of segmentation by thresholding, watershed transform, and object classification. The positioning of microelectrodes is obtained from the transmitted light channel images using the circular Hough transform. The proposed method was applied to images of dissociated culture of rat dorsal root ganglion (DRG) neuronal cells. The morphological and topological quantitative analysis carried out produced information regarding the state of culture, such as population count, neuron-to-neuron and neuron-to-microelectrode distances, soma morphologies, neuron sizes, neuron and microelectrode spatial distributions. Most of the analysis of microscopy images taken from neuronal cultures on MEA only consider simple qualitative analysis. Also, the proposed framework aims to standardize the image processing and to compute quantitative useful measures for integrated image-signal studies and further computational simulations. As results show, the implemented microelectrode identification method is robust and so are the implemented neuron segmentation and classification one (with a correct segmentation rate up to 84%). The quantitative information retrieved by the method is highly relevant to assist the integrated signal-image study of recorded electrophysiological signals as well as the physical aspects of the neuron culture on MEA. Although the experiments deal with DRG cell images, cortical and hippocampal cell images could also be processed with small adjustments in the image processing parameter estimation.

Quantitative estimation of the nonstationary behavior of neural spontaneous activity.

The "stationarity time" (ST) of neuronal spontaneous activity signals of rat embryonic cortical cells, measured by means of a planar Multielectrode Array (MEA), was estimated based on the "Detrended Fluctuation Analysis" (DFA). The ST is defined as the mean time interval during which the signal under analysis keeps its statistical characteristics constant. An upgrade on the DFA method is proposed, leading to a more accurate procedure. Strong statistical correlation between the ST, estimated from the Absolute Amplitude of Neural Spontaneous Activity (AANSA) signals and the Mean Interburst Interval (MIB), calculated by classical spike sorting methods applied to the interspike interval time series, was obtained. In consequence, the MIB may be estimated by means of the ST, which further includes relevant biological information arising from basal activity. The results point out that the average ST of MEA signals lies between 2-3 seconds. Furthermore, it was shown that a neural culture presents signals that lead to different statistical behaviors, depending on the relative geometric position of each electrode and the cells. Such behaviors may disclose physiological phenomena, which are possibly associated with different adaptation/facilitation mechanisms.

[Analysis of electrocardiographic recordings associated with acute myocardial infarction]. / Análise de registros eletrocardiográficos associados ao infarto agudo do miocárdio.

OBJECTIVE: Evaluate correlations between variations in eletrocardiogram (ECG) recordings and acute myocardial infarction. METHODS: Use of a low-cost software to digitalize printed and/or ".pdf" file format ECG recordings. Calculation of ST-segment area and amplitudes of the J and Y points. RESULTS: The amplitude of the Y point holds maximum correlation with troponin concentration. ST-segment elevation is not a good statistical indicator of myocardial infarction severity. There is a strong negative correlation between the amplitude of the J point and the amount of magnesium ions, but no statistical correlation with sodium or calcium ions. Neither method for calculating the ST-segment area (pixel counts and interpolation) indicated any significant differences in the results. CONCLUSION: The software used proved to be functional and cost-effective. Y point amplitude is a sensitive marker of myocardial infarction, and is also a calculation method both simpler to use and less subject to error than the calculation of the ST-segment elevation area.

Análise de registros eletrocardiográficos associados ao infarto agudo do miocárdio / Analysis of electrocardiographic recordings associated with acute myocardial infarction

OBJETIVO: Avaliar correlações entre as variações do eletrocar¡diograma (ECG) e o infarto agudo do miocárdio. MÉTODOS: Uso de software de baixo custo para digitalização de ECG impressos e/ou em formato "pdf". Cálculo de área do segmento ST e das amplitudes dos pontos J e Y RESULTADOS: A amplitude do ponto Y possui máxima correlação com a concentração da enzima troponina. O supradesnivelamento do segmento ST não se constitui bom indicador estatístico da gravidade do infarto. Existe uma forte correlação negativa entre a amplitude do ponto J e a quantidade de íons magnésio, mas nenhuma correlação estatística com os íons sódio ou cálcio. Os dois métodos de cálculo da área do segmento ST (contagem de pixels e interpolação) não mostraram diferenças significativas nos resultados. CONCLUSÃO: O software utilizado mostrou-se viável do ponto de vista econômico e funcional. A amplitude do ponto Y é um marcador sensível à ocorrência do infarto, tendo cálculo mais simples e menos sujeito a erros do que o cálculo da área de supradesnivelamento do segmento ST.