Developing a dynamic virtual stimulation protocol to induce linear egomotion during orthostatic posture control test

Abstract Introduction In this work, the effect of a dynamic visual stimulation (DS) protocol was used to induce egomotion, the center of pressure (COP) displacement response. Methods DS was developed concerning the scenario structure (chessboard-pattern floor and furniture) and luminance. To move the scenario in a discrete forward (or backward) direction, the furniture is expanded (or reduced) and the black and white background is reversed during floor translation while the luminance is increased (or reduced) by steps of 2 cd/m2. This protocol was evaluated using COP signals from 29 healthy volunteers: standing on a force platform observing the virtual scene (1.72 × 1.16 m) projected 1 m ahead (visual incidence angle: θl = 81.4° and θv = 60.2°), which moves with constant velocity (2 m/s) during 250 ms. A set of 100 DS was applied in random order, interspersed by a 10 s of static scene. Results The Tukey post-hoc test (p < 0.001) indicated egomotion in the same direction of DS. COP displacement increased over stimulation (8.4 ± 1.7 to 22.6 ±5.3 mm), as well as time to recover stability (4.1 ± 0.4 to 7.2 ± 0.6 s). The peak of egomotion during DSF occurred 200 ms after DSB (Wilcoxon, p = 0.002). Conclusion The dynamic configuration of this protocol establishes virtual flow effects of linear egomotion dependent on the direction of the dynamic visual stimulation. This finding indicates the potential application of the proposed virtual dynamic stimulation protocol to investigate the cortical visual evoked response in postural control studies.

Characterization of the variation of health care taking into account the costs of hospital admissions for acute myocardial infarction in Brazilian Unified Health System. / Caracterização dos padrões de variação dos cuidados de saúde a partir dos gastos com internações por infarto agudo do miocárdio no Sistema Único de Saúde.

INTRODUCTION: The global epidemiologic scenario indicates an increase in cardiovascular disease rates, with special emphasis on acute myocardial infarction (AMI), owing to its large magnitude and severity. In Brazil, coronary diseases now account for about 5% of hospital admission expenditures. OBJECTIVE: To characterize the admissions in the Brazilian Unified Health System of patients with AMI, by identifying clusters suggested by a traditional cluster analysis and by a multiple correspondence analysis (MCA). METHODS: The records of the Hospital Information System/Brazilian Unified Health System with a primary diagnosis of AMI in the State of Rio de Janeiro, Brazil, 2002, were selected and subsequently related to the records of the Mortality Information System. Next, an MCA and a metric called the tolerance distance were used for cluster identification. The variable of interest was "hospital expenditures", classified into two categories (above and below BRL 905). RESULTS: "Higher costs" were associated with "use of the Intensive Care Unit (ICU)" and "moderate severity of the case" and "lower costs" with "low severity" and "nonuse of the ICU". On the other hand, high severity cases, with no apparent association with "use of ICU" or other categories. Other associations identified were "lower costs" and "no displacement of the patient," "female," "age between 56 and 75 years," "death within 30 days," and "death within 1 year". CONCLUSIONS: The nonclustered characteristic of the most serious cases and the association between "deaths" and "lower costs" suggests that the technological resources available during hospitalization for AMI are not being properly used.

Caracterização dos padrões de variação dos cuidados de saúde a partir dos gastos com internações por infarto agudo do miocárdio no Sistema Único de Saúde / Characterization of the variation of health care taking into account the costs of hospital admissions for acute myocardial infarction in Brazilian Unified Health System

RESUMO: Introdução: O cenário epidemiológico mundial revela um crescimento das doenças cardiovasculares, no qual se destaca o infarto agudo do miocárdio (IAM), devido à sua grande magnitude e severidade. No Brasil, doenças coronarianas representam já cerca de 5% dos gastos com internação hospitalar. Objetivo: Caracterizar as internações dos pacientes do Sistema Único de Saúde (SUS) por IAM por meio da identificação de agrupamentos sugeridos por uma análise de agrupamentos tradicional e por uma análise de correspondência múltipla (ACM). Métodos: Registros do Sistema de Internações Hospitalares (SIH/SUS) com diagnóstico principal de IAM, no Estado do Rio de Janeiro, 2002, foram selecionados e posteriormente relacionados aos do Sistema de Informações sobre Mortalidade (SIM/SUS). A seguir, uma ACM e uma métrica chamada distância de tolerância foram utilizadas para a identificação de clusters , sendo a variável de interesse "gastos com internação" classificada em duas categorias (acima e abaixo de R$ 905,00). Resultados: Foi possível associar "maiores gastos" com "utilização de Centro de Tratamento Intensivo (CTI)" e com "gravidade moderada do caso", e "menores gastos" com "gravidade leve" e "não utilização de CTI". Por outro lado, casos de alta gravidade apresentaram-se isolados, sem associação com CTI ou outras variáveis. Também foi detectada associação entre a categoria "menores gastos" e as categorias: "não deslocamento do paciente", "sexo feminino", "idade entre 56 e 75 anos", "óbito até 30 dias" e "óbito até 1 ano". Conclusão: o aspecto isolado dos casos de maior gravidade e a associação entre "óbitos" e "menores gastos" sugere que os recursos tecnológicos disponíveis durante a internação por IAM não estão sendo adequadamente empregados.

ABSTRACT: Introduction: The global epidemiologic scenario indicates an increase in cardiovascular disease rates, with special emphasis on acute myocardial infarction (AMI), owing to its large magnitude and severity. In Brazil, coronary diseases now account for about 5% of hospital admission expenditures. Objective: To characterize the admissions in the Brazilian Unified Health System of patients with AMI, by identifying clusters suggested by a traditional cluster analysis and by a multiple correspondence analysis (MCA). Methods: The records of the Hospital Information System/Brazilian Unified Health System with a primary diagnosis of AMI in the State of Rio de Janeiro, Brazil, 2002, were selected and subsequently related to the records of the Mortality Information System. Next, an MCA and a metric called the tolerance distance were used for cluster identification. The variable of interest was "hospital expenditures", classified into two categories (above and below BRL 905). Results: "Higher costs" were associated with "use of the Intensive Care Unit (ICU)" and "moderate severity of the case" and "lower costs" with "low severity" and "nonuse of the ICU". On the other hand, high severity cases, with no apparent association with "use of ICU" or other categories. Other associations identified were "lower costs" and "no displacement of the patient," "female," "age between 56 and 75 years," "death within 30 days," and "death within 1 year". Conclusions: The nonclustered characteristic of the most serious cases and the association between "deaths" and "lower costs" suggests that the technological resources available during hospitalization for AMI are not being properly used.

Polyvinyl chloride plastisol breast phantoms for ultrasound imaging.

Ultrasonic phantoms are objects that mimic some features of biological tissues, allowing the study of their interactions with ultrasound (US). In the diagnostic-imaging field, breast phantoms are an important tool for testing performance and optimizing US systems, as well as for training medical professionals. This paper describes the design and manufacture of breast lesions by using polyvinyl chloride plastisol (PVCP) as the base material. Among the materials available for this study, PVCP was shown to be stable, durable, and easy to handle. Furthermore, it is a nontoxic, nonpolluting, and low-cost material. The breast's glandular tissue (image background) was simulated by adding graphite powder with a concentration of 1% to the base material. Mixing PVCP and graphite powder in differing concentrations allows one to simulate lesions with different echogenicity patterns (anechoic, hypoechoic, and hyperechoic). From this mixture, phantom materials were obtained with speed of sound varying from 1379.3 to 1397.9ms(-1) and an attenuation coefficient having values between 0.29 and 0.94dBcm(-1) for a frequency of 1MHz at 24°C. A single layer of carnauba wax was added to the lesion surface in order to evaluate its applicability for imaging. The images of the phantoms were acquired using commercial ultrasound equipment; a specialist rated the images, elaborating diagnoses representative of both benign and malignant lesions. The results indicated that it was possible to easily create a phantom by using low-cost materials, readily available in the market and stable at room temperature, as the basis of ultrasonic phantoms that reproduce the image characteristics of fatty breast tissue and typical lesions of the breast.

Breast ultrasound despeckling using anisotropic diffusion guided by texture descriptors.

Breast ultrasound (BUS) is considered the most important adjunct method to mammography for diagnosing cancer. However, this image modality suffers from an intrinsic artifact called speckle noise, which degrades spatial and contrast resolution and obscures the screened anatomy. Hence, it is necessary to reduce speckle artifacts before performing image analysis by means of computer-aided diagnosis systems, for example. In addition, the trade-off between smoothing level and preservation of lesion contour details should be addressed by speckle reduction schemes. In this scenario, we propose a BUS despeckling method based on anisotropic diffusion guided by Log-Gabor filters (ADLG). Because we assume that different breast tissues have distinct textures, in our approach we perform a multichannel decomposition of the BUS image using Log-Gabor filters. Next, the conduction coefficient of anisotropic diffusion filtering is computed using texture responses instead of intensity values as stated originally. The proposed algorithm is validated using both synthetic and real breast data sets, with 900 and 50 images, respectively. The performance measures are compared with four existing speckle reduction schemes based on anisotropic diffusion: conventional anisotropic diffusion filtering (CADF), speckle-reducing anisotropic diffusion (SRAD), texture-oriented anisotropic diffusion (TOAD), and interference-based speckle filtering followed by anisotropic diffusion (ISFAD). The validity metrics are the Pratt's figure of merit, for synthetic images, and the mean radial distance (in pixels), for real sonographies. Figure of merit and mean radial distance indices should tend toward '1' and '0', respectively, to indicate adequate edge preservation. The results suggest that ADLG outperforms the four speckle removal filters compared with respect to simulated and real BUS images. For each method--ADLG, CADF, SRAD, TOAD and ISFAD--the figure of merit median values are 0.83, 0.40, 0.39, 0.51 and 0.59, and the mean radial distance median results are 4.19, 6.29, 6.39, 6.43 and 5.88.

[Correspondence analysis: a theoretical basis for categorical data interpretation in health sciences]. / Análise de Correspondência: bases teóricas na interpretação de dados categóricos em Ciências da Saúde.

Categorical variables are common in the biomedical field, and many descriptive methods have been proposed for revealing intrinsic patterns in data. Correspondence Analysis is an especially useful method for categorical data analysis of large contingency tables. Although numerous studies have been published on this method, most Portuguese-language articles have failed to explore its full potential, focusing only on graphical interpretation. The current paper reviews the method, showing that graphical analysis can be enriched by the right statistics. The article presents the mathematical basis for correspondence analysis and its most frequently used statistics. The procedure has shown that such statistics enrich symmetric map evaluation, that a low relative frequency category can be represented by supplementary category points, and that inertia contributions are highly related to residual analysis of contingency tables, not easily visualized by symmetric maps. Correspondence Analysis has proven advantageous when compared to principal components analysis.

Análise de Correspondência: bases teóricas na interpretação de dados categóricos em Ciências da Saúde / Correspondence Analysis: a theoretical basis for categorical data interpretation in Health Sciences / Análisis de Correspondencia: bases teóricas para la interpretación de datos categóricos en Ciencias de Salud

Na área biomédica, a ocorrência de dados categóricos é comum, e métodos de análise específicos para este tipo de dado são usados para revelar padrões existentes. A Análise de Correspondência é uma dessas técnicas, utilizada na análise de tabelas de contingência de grande porte. A maioria dos trabalhos publicados em periódicos brasileiros foca apenas na sua interpretação gráfica, não abordando outras potencialidades da técnica. O objetivo do trabalho é mostrar a técnica não limitada à análise gráfica, mas também utilizar estatísticas que permitem sua análise quantitativa. Exemplo mostra que a análise gráfica é enriquecida com a utilização dessas estatísticas, e que a inclusão de uma categoria com baixa ocorrência pode ser considerada como categoria suplementar devido à sua baixa contribuição à inércia. Assim, diminui-se a subjetividade na análise, sendo possível revelar a relação entre as categorias com a análise de resíduos, aspecto este não facilmente observado graficamente. Comparação com a Análise de Componentes Principais mostrou a vantagem da técnica.

Categorical variables are common in the biomedical field, and many descriptive methods have been proposed for revealing intrinsic patterns in data. Correspondence Analysis is an especially useful method for categorical data analysis of large contingency tables. Although numerous studies have been published on this method, most Portuguese-language articles have failed to explore its full potential, focusing only on graphical interpretation. The current paper reviews the method, showing that graphical analysis can be enriched by the right statistics. The article presents the mathematical basis for correspondence analysis and its most frequently used statistics. The procedure has shown that such statistics enrich symmetric map evaluation, that a low relative frequency category can be represented by supplementary category points, and that inertia contributions are highly related to residual analysis of contingency tables, not easily visualized by symmetric maps. Correspondence Analysis has proven advantageous when compared to principal components analysis.

En el campo biomédico, los datos categóricos son frecuentemente utilizados y los métodos de análisis específicos son empleados para revelar patrones intrínsecamente existentes en los mismos. El Análisis de Correspondencias es una de estas técnicas, siendo útil en el análisis de tablas de contingencia con un gran número de clases. A pesar de que muchos artículos han explorado esta técnica, la mayoría de trabajos en revistas brasileñas se centra sólo en su interpretación gráfica. El objetivo de este trabajo es incluir estadísticas que permitan la interpretación cuantitativa de la técnica. Como ejemplo, tenemos el análisis de un mapa simétrico enriquecido con el uso de estadísticas, en el cual la inclusión de una clase de baja ocurrencia puede ser considerada como una categoría suplementaria, debido a su baja contribución a la inercia de datos. Por lo tanto, disminuye la subjetividad en el análisis, siendo posible ahora revelar la relación entre las categorías con el análisis residual, lo que no es fácil observar en los gráficos. La comparación con el análisis de componentes principales mostró sus ventajas.

Rice detector: proposal of a novel objective response detection technique

INTRODUCTION: The detection of the somatosensory response (SR) is an important tool for the neurophysiological evaluation in the intra and post-operative period of some vascular and spine surgeries. Particularly, the SR identification with a maximum false positive ratio by means of Objective Response Detection (ORD) techniques could lead to a less subjective procedure. In this work a novel ORD, the Rice Detector (RD), is presented and its theoretical critical value is obtained. METHODS: The probability of detection (PD) of RD is assessed for different numbers of eletroencephalographic (EEG) signal epochs (M = 30, 60, 120, 240) and signal-to-noise ratios (-20 to 10 dB, in steps of 1 dB) by means of simulation. The simulated PD curves (PDc) are compared with the theoretical ones and with the PDc of the Magnitude-Squared Coherence (MSC), a well-known ORD technique. The performance of RD and MSC are also compared for real EEG data. The comparison is based on the DP for estimates calculated with M = 30, 60, 120 and 240 epochs. RESULTS: The results showed that the simulated PDc follow the theoretical ones and both the MSC and RD present similar performance, with slight advantage for this latter at low M-values. However, for real data, no statistical significant difference (proportion test with alpha=0.05) was found between MSC and RD. CONCLUSION: Both techniques presented mean detection rates varying from 70% to 90%, even for intermediate M-value (120 epochs), and can be useful for evoked response detection applications.

Segmenting mammographic microcalcifications using a semi-automatic procedure based on Otsu's method and morphological filters

INTRODUCTION: Breast cancer has the second highest world's incidence rate, according to the Brazilian National Cancer Institute (INCa). Clinical examination and mammography are the best methods for early diagnosis. Computer-aided detection (CADe) and computer-aided diagnosis (CADx) systems are developed to improve mammographic diagnosis. Basically, CADx systems have three components: (i) segmentation, (ii) parameters extraction and selection, (iii) lesion classification. The first step for a CADx system is segmentation. METHODS: A microcalcification segmentation method is proposed, based on morphological operators, Otsu's Method and radiologists' knowledge. Pre-processing with top-hat operators improves contrast and reduces background noise. The Otsu's method automatically selects the best grey-level threshold to segment microcalcifications, obtaining binary images. Following, inferior reconstruction and morphological dilatation operators are applied to reconstruct lost structure details and fill small flaws in the segmented microcalcifications. Finally, the Canny edge detection is applied to identify microcalcifications contour candidates for each region-of-interest (ROI). Two experienced radiologists intervene in this semi-automatic method, firstly, selecting the ROI and, then, analyzing the segmentation result. The method was assessed in 1000 ROIs from 158 digital images (300 dpi, 8 bits). RESULTS: Considering the radiologists opinion, the rates of ROIs adequately segmented to establish a diagnosis hypothesis were 97.8% for one radiologist and 97.3% for the other. Using the Area Overlap Measure (AOM) and the 2136 microcalcifications delineated by an experienced radiologist as gold standards, the method achieved an average AOM of 0.64±0.14, being 0.56±0.09 for small microcalcifications and 0.66±0.13 for the large ones. Moreover, AOM was 0.64±0.13 for the benign and 0.64±0.14 for the malignant lesions with no statistical differences between them. CONCLUSION: Based on these findings, the proposed method could be used to develop a CADx system that could help early breast cancer detection.

Effect of co-transporter blockers on non-synaptic epileptiform activity-computational simulation.

The important role of cation-chloride co-transporters in epilepsy is being supported by an increasing number of investigations. However, enormous complexity is involved since the action of these co-transporters has effects on the ionic homeostasis influencing directly the neuronal excitability and the tissue propensity to sustain seizure. To unravel the complex mechanisms involving the co-transporters action during seizure, this paper shows simulations of non-synaptic epileptiform activity and the effect of the blockage of the two different types of cation-chloride co-transporters present in the brain: Na, K and 2Cl co-transporter (NKCC) and K and Cl co-transporter (KCC). The simulations were performed with an electrochemical model representing the non-synaptic structure of the granule cell layer of the dentate gyrus (DG) of the rat hippocampus. The simulations suggest: (i) the potassium clearance is based on the systemic interplay between the Na/K pump and the NKCC co-transporters; (ii) the simultaneous blockage of the NKCC of the neurons and KCC of glial cells acts efficiently suppressing the epileptiform activities; and (iii) the simulations show that depending on the combined blockage of the co-transporters, the epileptiform activities may be suppressed or enhanced.

[Multiple correspondence analysis in the evaluation of hospital pharmacy services in Brazil]. / Análise de correspondência múltipla na avaliação de serviços de farmácia hospitalar no Brasil.

This study aimed to evaluate associations among variables in hospital pharmacy services. Thirty variables were used from the project Diagnosis of Hospital Pharmacies in Brazil pertaining to the overall description of the hospital, overall characterization of the hospital pharmacy service, and stages in pharmaceutical care. The statistical techniques were multiple correspondence and cluster analysis. Dimension 1 of the multiple correspondence analysis explained 90.6% of variance, differentiating between hospital pharmacy services based on the presence of certain activities, thus suggesting an axis of characterization for the hospital pharmacy services. The results indicate a direct relationship between compliance with the activities and the type of hospital and pharmacists with specialized training. Cluster analysis identified six clusters related to hospital size; greater compliance with the activities was associated with large hospitals and those with a pharmacist (more time dedicated to the hospital pharmacy service and higher level of training). The study concludes that the techniques were able to identify associations and a concise range of variables for a comprehensive evaluation of hospital pharmacy services in Brazil.

Análise de correspondência múltipla na avaliação de serviços de farmácia hospitalar no Brasil / Multiple correspondence analysis in the evaluation of hospital pharmacy services in Brazil / Análisis de correspondencia múltiple en la evaluación de servicios de farmacia hospitalaria en Brasil

O estudo objetivou avaliar a existência de associações entre variáveis de serviços de farmácia hospitalar. Foram utilizadas 30 variáveis do projeto Diagnóstico da Farmácia Hospitalar no Brasil relativas à caracterização geral do hospital, caracterização geral do serviço de farmácia hospitalar e etapas da assistência farmacêutica. A análise de correspondência múltipla e a análise de agrupamentos foram utilizadas. A dimensão 1 da análise de correspondência múltipla explicou 90,6% da variabilidade, diferenciando os serviços de farmácia hospitalar conforme a presença de atividades, sugerindo assim um eixo de caracterização da estrutura dos serviços de farmácia hospitalar. Os resultados indicam relação direta entre cumprimento das atividades e tipo de hospital e farmacêuticos com especialização. A análise de agrupamentos identificou seis grupos relativos ao porte do hospital, tendo maior cumprimento de atividades os serviços de farmácia hospitalar em unidades de grande porte e com farmacêutico (maior tempo dedicado ao serviço de farmácia hospitalar e maior nível de treinamento). Conclui-se que as técnicas foram capazes de identificar as associações e um elenco conciso de variáveis para uma avaliação abrangente dos serviços de farmácia hospitalar no país.

This study aimed to evaluate associations among variables in hospital pharmacy services. Thirty variables were used from the project Diagnosis of Hospital Pharmacies in Brazil pertaining to the overall description of the hospital, overall characterization of the hospital pharmacy service, and stages in pharmaceutical care. The statistical techniques were multiple correspondence and cluster analysis. Dimension 1 of the multiple correspondence analysis explained 90.6% of variance, differentiating between hospital pharmacy services based on the presence of certain activities, thus suggesting an axis of characterization for the hospital pharmacy services. The results indicate a direct relationship between compliance with the activities and the type of hospital and pharmacists with specialized training. Cluster analysis identified six clusters related to hospital size; greater compliance with the activities was associated with large hospitals and those with a pharmacist (more time dedicated to the hospital pharmacy service and higher level of training). The study concludes that the techniques were able to identify associations and a concise range of variables for a comprehensive evaluation of hospital pharmacy services in Brazil.

El estudio tuvo como objetivo evaluar la existencia de asociaciones entre variables de servicios de farmacia hospitalaria. Se utilizaron 30 variables del proyecto Diagnóstico de Farmacia Hospitalaria en Brasil, relativas a la caracterización general del hospital, caracterización general del servicio de farmacia hospitalaria y etapas de la asistencia farmacéutica. Se utilizaron técnicas estadísticas como el análisis de correspondencia múltiple y el análisis de agrupamientos. La dimensión 1 del análisis de correspondencia múltiple explicó un 90,6% de la variabilidad, diferenciando los servicios de farmacia hospitalaria conforme la presencia de actividades, sugiriendo así un eje de caracterización de la estructura de los servicios de farmacia hospitalaria. Los resultados indican la relación directa entre el cumplimiento de las actividades y el tipo de hospital y farmacéuticos con especialización. El análisis de agrupamientos identificó seis grupos relativos al porte del hospital, consiguiendo un mayor cumplimiento de actividades los servicios de farmacia hospitalaria en unidades de gran porte y con farmacéutico (mayor tiempo dedicado al servicio de farmacia hospitalaria y mayor nivel de experiencia). Se concluye que las técnicas fueron capaces de identificar las asociaciones y un elenco conciso de variables para una evaluación englobadora de los servicios de farmacia hospitalaria en el país.

Enhanced synaptic connectivity in the dentate gyrus during epileptiform activity: network simulation.

Structural rearrangement of the dentate gyrus has been described as the underlying cause of many types of epilepsies, particularly temporal lobe epilepsy. It is said to occur when aberrant connections are established in the damaged hippocampus, as described in human epilepsy and experimental models. Computer modelling of the dentate gyrus circuitry and the corresponding structural changes has been used to understand how abnormal mossy fibre sprouting can subserve seizure generation observed in experimental models when epileptogenesis is induced by status epilepticus. The model follows the McCulloch-Pitts formalism including the representation of the nonsynaptic mechanisms. The neuronal network comprised granule cells, mossy cells, and interneurons. The compensation theory and the Hebbian and anti-Hebbian rules were used to describe the structural rearrangement including the effects of the nonsynaptic mechanisms on the neuronal activity. The simulations were based on neuroanatomic data and on the connectivity pattern between the cells represented. The results suggest that there is a joint action of the compensation theory and Hebbian rules during the inflammatory process that accompanies the status epilepticus. The structural rearrangement simulated for the dentate gyrus circuitry promotes speculation about the formation of the abnormal mossy fiber sprouting and its role in epileptic seizures.

Investigating the center of pressure velocity Romberg's quotient for assessing the visual role on the body sway / Avaliando a importância da visão nas oscilações posturais utilizando o quociente de Romberg da velocidade do centro de pressão

The classical Romberg's test based on stabilometric tests in eyes open (EO) and closed (EC) conditions was used for investigating the influence of visual feedback in the body sway control in healthy adult subjects. Stabilograms from 144 subjects (aged 18-40) resting over a force platform were recorded for 30 s in EO and 30 s in EC conditions. The mean velocity was obtained for EO (VmEO) and EC (VmEC) in both anterior-posterior (y) and medial-lateral (x) directions and in the (x,y) plane, and thus used for computing the respective Romberg's quotient (RQ V). All Vm and RQ V parameter histograms presented unimodal asymmetric shapes, which were adequately fitted to lognormal distributions (Kolmogorov-Smirnov test, p > 0.05). These findings suggest a single homogeneous group in terms of visual strategy. Taking the threshold scores (95% confidence interval) of the Vm and RQ V distributions, only four subjects (2.7%) presented values below the lower limit, as expected by the confidence level (two tailed, 5%). A strong dependence was also found between each RQ V and the respective VmEC (Spear correlation > 0.86, R² > 74.0%), with VmEO presenting almost negligible coefficients of determination (R² < 2.9%). One can conclude that RQ V derived from a single stabilometric trial could be not sufficient for the diagnosis of body sway control impairment by vision. Nevertheless, the RQ V could be useful to indicate subjects to carry out additional tests to investigate a possible deficit in the integration of the visual information in the postural control system.

O Teste de Romberg clássico, baseado em testes estabilométricos nas condições de olhos abertos (EO) e fechados (EC), tem sido utilizado para investigar a influência da realimentação visual no controle das oscilações posturais em sujeitos adultos saudáveis. Estabilogramas de 144 sujeitos (18 a 40 anos) em posição ortostática sobre uma plataforma de força foram coletados durante 30 s na condição EO e 30 s em EC. As velocidades médias para EO (VmEO) e EC (VmEC), obtidas nas direções anteroposterior (y), mediolateral (x) e no plano (x,y), foram utilizadas no cálculo dos respectivos quocientes de Romberg (RQV). Os histogramas dos parâmetros Vm e RQV apresentaram morfologia unimodal assimétrica, aos quais foram ajustadas distribuições lognormais (Teste de Kolmogorov-Smirnov, p > 0,05). Tais distribuições sugerem haver um único grupo homogêneo no que concerne à estratégia visual. Considerando o intervalo de confiança de 95%, somente quatro sujeitos (2,7%) apresentaram valores de Vm e QRV abaixo do limite inferior, percentual este compatível com o teste bicaudal. A Correlação de Spear entre o RQV e seu respectivo VmEC foi sempre superior a 0,86, sendo o coeficiente de determinação R2 > 74,0%, enquanto que com VmEO R2 < 2,9%. Tais achados sugerem que o RQV obtido a partir de um único teste estabilométrico não seria adequado ao diagnóstico de problemas de controle das oscilações posturais ocasionados pela visão. No entanto, o RQV pode ser útil para indicar a realização de testes adicionais com vistas a investigar possível déficit na integração da informação visual no sistema de controle postural.

Using Objective Response Detection techniques for detecting the tibial somatosensory evoked response with different stimulation rates.

This work investigates the influence of the stimulus frequency in the performance of two Objective Response Detection (ORD) techniques, the Magnitude-Squared Coherence (MSC) and the Component Synchrony Measure (CSM), as applied in somatosensory stimulation. Electroencephalographic signals were collected (10-20 International System) from forty adult volunteers without history of neurological pathologies. The stimuli were applied to the right posterior tibial nerve at the frequencies of 2, 5, 7 and 9 Hz and motor threshold intensity level. The detection was based on the rejection of the null hypothesis of response absence (significance level α=0.05 and M=100 and 500 epochs). The performances of the MSC at the four stimulation frequencies were compared, two-by-two, using the Proportion Test applied to the mean percentage rates in the total (2-100 Hz) and optimal (20-60 Hz) bands. The same was proceeded to the CSM. The evaluated derivations were Cz, C4, Pz and P4. No significant difference was found for any studied technique (MSC or CSM), any M-value, at any derivation. Thus, the highest stimulation frequency (9 Hz) can be used in order to obtain a reduction in the time of response detection in an ORD approach for a fixed M-value.

EEG changes during sequences of visual and kinesthetic motor imagery.

The evoked cerebral electric response when sequences of complex motor imagery (MI) task are executed several times is still unclear. This work aims at investigating the existence of habituation in the cortical response, more specifically in the alpha band peak of parietal and occipital areas (10-20 international system electroencephalogram, EEG, protocol). The EEG signals were acquired during sequences of MI of volleyball spike movement in kinesthetic and visual modalities and also at control condition. Thirty right-handed male subjects (18 to 40 years) were assigned to either an 'athlete' or a 'non-athlete' group, both containing 15 volunteers. Paired Wilcoxon tests (with alpha=0.05) indicates that sequential MI of complex tasks promotes cortical changes, mainly in the power vicinity of the alpha peak. This finding is more pronounced along the initial trials and also for the athletes during the modality of kinesthetic motor imagery.

EEG changes during sequences of visual and kinesthetic motor imagery / Alterações no EEG durante sequencias de imagética motora visual e cinestésica

The evoked cerebral electric response when sequences of complex motor imagery (MI) task are executed several times is still unclear. This work aims at investigating the existence of habituation in the cortical response, more specifically in the alpha band peak of parietal and occipital areas (10-20 international system electroencephalogram, EEG, protocol). The EEG signals were acquired during sequences of MI of volleyball spike movement in kinesthetic and visual modalities and also at control condition. Thirty right-handed male subjects (18 to 40 years) were assigned to either an 'athlete' or a 'non-athlete' group, both containing 15 volunteers. Paired Wilcoxon tests (with α=0.05) indicates that sequential MI of complex tasks promotes cortical changes, mainly in the power vicinity of the alpha peak. This finding is more pronounced along the initial trials and also for the athletes during the modality of kinesthetic motor imagery.

A resposta elétrica cerebral evocada quando sequencias de imagética motora (MI) de tarefas complexas são executadas seguidamente no tempo permanecem desconhecidas. Este trabalho objetivou investigar a existência de habituação da resposta cortical, mais especificamente na banda do pico de alfa de áreas parietais e occipitais (sistema internacional 10-20, eletroencefalograma, protocolo de EEG). Os sinais de EEG foram adquiridos durante sequências de MI do movimento de ataque do voleibol nas modalidades cinestésica e visual, e também em condição de controle. Trinta voluntários adultos (entre 18 e 40 anos), destros, do gênero masculino foram agrupados como 'atletas' ou 'não-atletas', sendo cada grupo composto de 15 voluntários. Testes pareados de Wilcoxon (com α=0.05) indicaram que a MI sequencial de tarefas complexas promoveram alterações nas respostas corticais, mais especificamente na região ao redor do pico de alfa. Este achado foi mais pronunciado ao longo dos trechos iniciais e também nos atletas durante a modalidade cinestésica de imagética motora.

Análise computacional da textura de tumores de mama em imagens por ultrassom de pacientes submetidas a cirurgia conservadora / Computer-assisted analysis of breast tumors texture on sonographic images of patients submitted to breast-conserving surgery

OBJETIVO: Avaliar as características de textura de lesões de mama em imagens por ultrassom de pacientes submetidas a cirurgia conservadora que apresentaram, ou não, recidiva. MATERIAIS E MÉTODOS: As imagens de ultrassom de 36 pacientes submetidas a cirurgia conservadora, com 12 tendo apresentado recidiva local e 24 que não apresentaram recidiva no local da cirurgia, foram divididas em: 3 malignas na mama oposta, 7 nódulos benignos, 5 hiperplasias atípicas e 9 alterações fibrocísticas. A textura das lesões foi quantificada utilizando-se dez parâmetros calculados da matriz de coocorrência e da curva de complexidade. Análise discriminante linear foi aplicada aos parâmetros para discriminação de lesões de mama em pacientes submetidas a cirurgia conservadora que apresentaram, ou não, recidiva. RESULTADOS: Avaliando-se a capacidade dos parâmetros em distinguir as recidivas do grupo composto por lesões não recidivas benignas e hiperplasias atípicas, obteve-se especificidade de 100 por cento, com valores de acurácia e sensibilidade superiores a 91 por cento. Num segundo teste, foi possível distinguir as cinco hiperplasias, das lesões não recidivas benignas. CONCLUSÃO: Apesar do número reduzido de casos, os resultados obtidos são encorajadores, sugerindo que o uso da quantificação da textura pode auxiliar na diferenciação entre lesões benignas, hiperplasias atípicas e lesões malignas de origem recidiva.

OBJECTIVE: The purpose of this study was to assess the features of breast lesion texture on sonographic images of patients submitted to breast-conserving surgery, with or without tumor recurrence. MATERIALS AND METHODS: Sonographic images of 36 patients submitted to conservative surgery for breast cancer, 12 of them with, and 24 without local recurrence, included 3 contralateral malignant lesions, 7 benign lumps (3 cysts and 4 fibroadenomas), 5 atypical hyperplasias and 9 fibrocystic changes. The quantification of features of breast lesion texture was based on ten parameters calculated from gray-level co-occurrence matrix and complexity curve. Linear discriminant analysis was applied to the texture parameters for differentiating between breast lesions in women submitted to conservative surgery with and without tumor recurrence. RESULTS: The assessment of performance of texture parameters in distinguishing lesion recurrences in a group including benign lumps and atypical hyperplasias demonstrated specificity of 100 percent, and accuracy and sensitivity > 91 percent. Another test demonstrated that texture parameters were useful in the differentiation between atypical hyperplasias and benign lumps. CONCLUSION: Despite the limited number of cases, the present results can be considered as promising, suggesting that texture parameters may help in the differentiation among benign lumps, atypical hyperplasias and recurrent malignant lesions.

Potenciais relacionados a eventos (ERP) revelam o curso da derivação sintática e a dinâmica da integração entre micromódulos de cognição de linguagem / Event-related brain potentials (ERP) reveal the course of syntactic derivation and the dynamics of integration among micromodules of language cognition

Este é um estudo em Neurociência da Linguagem conduzido a partir do modelo teórico Minimalismo, da Gramática Gerativa. Utilizando a técnica de extração de potenciais relacionados a evento (ERPs), em experimento com 29 sujeitos normais, investigamos a neurofisiologia da concatenação (merge) do sujeito e testamos a hipótese bottom-up da derivação de sentença, que postula que primeiramente o verbo se concatenaria ao seu complemento, e depois o composto verbo-complemento se concatenaria ao sujeito. Assim, a ordem do curso da derivação, ou seja, das tarefas cognitivas na computação de linguagem, seria diferente da ordem linear dos constituintes na sentença. Os resultados experimentais ajudaram a entender sobre o curso da derivação sintática e a dinâmica da integração entre micromódulos envolvendo cognição de linguagem.