Recent refinements to cranial implants for rhesus macaques (Macaca mulatta).

The advent of cranial implants revolutionized primate neurophysiological research because they allow researchers to stably record neural activity from monkeys during active behavior. Cranial implants have improved over the years since their introduction, but chronic implants still increase the risk for medical complications including bacterial contamination and resultant infection, chronic inflammation, bone and tissue loss and complications related to the use of dental acrylic. These complications can lead to implant failure and early termination of study protocols. In an effort to reduce complications, we describe several refinements that have helped us improve cranial implants and the wellbeing of implanted primates.

A new treadmill-type motorized walking belt machine for video recording of the rat's gait and sciatic functional index measurement. A comparative study with other methods.

The sciatic functional index (SFI) is a remarkable tool to assess dysfunction and functional recovery of the sciatic nerve of rats. Usually measured on hind foot imprints on paper, a new method is now being proposed, by direct analysis of video recorded foot sole images obtained with a treadmill-type walking belt machine functioning with gait speed control (G1). Results were compared with the SFI measured on imprints on paper (G2) and on video recorded foot sole images obtained with a static see-through runway (G3). The right sciatic nerve of 19 adult female Wistar rats was crushed by the application of a controlled load. Impressions/images obtained both preoperatively and at weekly intervals for eight consecutive postoperative weeks were digitized, stored and analyzed in a computer loaded with specific software, the SFI being automatically calculated after measuring the appropriate parameters. SFI differed significantly between G1 and G2 and G1 and G3 (p<0.05), but not between G2 and G3 (p>0.05) during the first and second postoperative weeks, nonsignificant differences (p>0.05) being observed for any comparison between groups during the third through eighth postoperative weeks. We conclude that the three methods yielded equivalent results from the third week onward, but both video recording methods (G2 and G3) permitted a more adequate early evaluation (first and second weeks), since the SFI parameters were more easily identifiable. Images obtained with the walking belt machine are more uniform and sharper, thus contributing to reduce the influence of biases observed with imprints on paper.

Design and construction of a photoresistive sensor for monitoring the rat vibrissal displacement.

Rats sweep their vibrissae in a rhythmic and coordinated fashion in order to acquire tactile information from their environment. Measuring vibrissae movement has become a matter of increased attention, from several labs, over the last few years. We describe the design and construction of an inexpensive photoresistive sensor that registers horizontal vibrissae movement. The device consists of an LED array and a light-dependent resistor (LDR) covered by a coating with varying transparency along its axis. When a vibrissa is located in the sensor, it generates a shadowy line over the photosensitive material, thus changing the LDR resistance. These changes are transduced into voltage changes. Our measurements on vibrissa show that this simple and inexpensive sensor effectively monitors the movement of a single vibrissa.

Neurofisiologia da terapia manual / Neurophysiology of manual therapy

Introdução: A neurofisiologia vem evoluindo enormemente nas últimas décadas, possibilitando o melhor entendimento de técnicas utilizadas na reabilitação de pacientes com disfunção de movimento e dor. Técnicas de terapia manual estão se tornando cada vez mais populares com resultados bastante positivos. O estudo da aplicação destas técnicas permanece na maioria das vezes no ambiente clínico, mostrando comparativamente os benefícios da sua aplicação. Objetivo: Revisar os mecanismos neurofisiológicos da aplicação das técnicas de terapia manual. Métodos: O estudo baseia-se na revisão de literatura especializada sobre o tema, composta de livros e artigos publicados em revistas indexadas nacionais e internacionais. Conclusão: Os principais efeitos da aplicação das técnicas são: hipoalgesia, inibição do espasmo muscular por influência na excitabilidade do motoneurônio, melhora do controle motor e repercussões no sistema nervoso autônomo. Os benefícios parecem estar mais envolvidos com o efeito hipoalgésico, tanto por mecanismos periféricos quanto centrais.

Introduction: Neurophysiology has been largely developing in the last decades allowing a better understanding of the techniques used in the rehabilitation of patients with movement impairment and pain. Manual therapy techniques have become more popular with quite positive results. The application of these techniques are developed mostly in the clinical setting, showing, comparatively, the benefits of their application. Aim: To review the neurophysiological mechanisms of the application of manual therapy techniques. Methods: This study is a literature review, consisting of books and papers published in national and international journals. Conclusion: The main effects of the application of the techniques are: hypoalgesia, inhibition of muscle spasm by influence on the motoneuronal excitability, motor control improvement and repercussions on the autonomic nervous system. The benefits seem to be more related to the hypoalgesic effect in as much by peripheral mechanisms as central ones.

Estimulação transcraniana com corrente contínua associada ao tratamento multidisciplinar da fibromialgia: um estudo duplo-cego, aleatorizado e controlado / Transcranial direct current stimulation associated to multidisciplinary treatment for fibromyalgia: a double-blinded, randomized controlled trial

A estimulação transcortical com corrente contínua (ETCC) é uma técnica de estimulação não-invasiva do córtex cerebral que tem mostrado efeitos positivos no controle da dor crônica. A hipótese principal deste estudo foi verificar se a associação da ETCC ao tratamento multidisciplinar de pacientes com fibromialgia aumentaria os resultados no controle da dor e melhora da qualidade de vida. O desenho do estudo foi um ensaio clínico controlado, aleatorizado, duplo-cego e de braços paralelos. Vinte e três mulheres com fibromialgia receberam o tratamento habitual de reabilitação com a intervenção multidisciplinar e medicamentos e foram divididas aleatoriamente em um grupo com ETCC anódica sobre o córtex motor esquerdo e catódica na região supra-orbital direita, com corrente contínua de 2mA, por 20 minutos. O outro grupo recebeu estimulação sham, na qual a mesma disposição de eletrodos foi usada sobre o couro cabeludo, porém a corrente foi interrompida após 1 minuto, permanecendo desligada nos 19 minutos restantes. As sessões ocorreram uma vez por semana por 10 semanas consecutivas, sempre antes de terapia multidisciplinar. A dor foi quantificada ao início e ao final do tratamento pela escala pela visual analógica (EVA) e pela dolorimetria de pressão sobre os pontos dolorosos da fibromialgia. A qualidade de vida foi avaliada pelo Questionário de impacto da fibromialgia (FIQ) e SF-36. Como possíveis fatores de confusão, foram avaliados o humor e a capacidade funcional por meio do Índice de depressão de Beck (IDB), Escala de Hamilton (HAM) e questionário HAQ. Não foram descritos efeitos adversos graves. Houve melhora significativa da pontuação do domínio Dor do questionário SF-36, com efeito significante apenas no grupo sob estimulação ativa (de 26,6 ± 12,9 para 45,6 ± 15,1 ao final do tratamento, p=0,006). Nenhum dos demais desfechos apresentou melhora estatisticamente significativa, exceto FIQ que teve evolução marginalmente significativa no grupo ativo...

Transcranial direct current stimulation (tDCS) is a non-invasive technique of cortical brain stimulation which has shown some positive effects on chronic pain control. The main hypothesis of this study was to verify if the association of tDCS to the multidisciplinary approach in patients with fibromyalgia would increase the results for the control of pain and improve quality of life. The study design was a randomized, double-blinded, shamcontrolled clinical Trial of parallel arms. Twenty tree women with fibromyalgia received the usual treatment with the multidisciplinary approach and drugs, and were randomly allocated in a group with 2mA anodic tDCS for 20 minutes over the left primary motor cortex and the cathode was positioned over the right supra-orbital region. Another group with sham stimulation, with the same electrode positioning, had the electric current interrupted within 1 minute from of stimulation and remained off during the remaining 19 minutes. Stimulations occurred weekly for 10 weeks, always before the multidisciplinary intervention. Pain was rated at the begging of the treatment and after its end by the visual analogue scale (VAS) e pressure dolorimetry on fibromyalgia tender points. Quality of life was evaluated with the Fibromyalgia impact questionnaire (FIQ) and SF-36. As possible confounders, humor and functional capacity were evaluated with Beck depression index (BDI), Hamilton scale (HAM) and HAQ. There were no serious adverse effects. There was a significant improvement in the Pain domain of SF-36, with significant effect only in the group under active tDCS (from 26.6 ± 12.9 to 45.6 ± 15.1 in the end of the treatment, p=0.006). Any of the other outcomes showed statistically significant improvement, except for FIQ, which presented with a marginally significant improvement in the active group (62.1 ± 11.5 to 49.2 ± 21.2; p=0.056) and HAQ (1.51 ± 0.47 to 1.24 ± 0.4; p=0.0005), without any difference in both groups...

Avoiding spectral leakage in objective detection of auditory steady-state evoked responses in the inferior colliculus of rat using coherence.

Local field potentials (LFP) are bioelectric signals recorded from the brain that reflect neural activity in a high temporal resolution. Separating background activity from that evoked by specific somato-sensory input is a matter of great clinical relevance in neurology. The coherence function is a spectral coefficient that can be used as a detector of periodic responses in noisy environments. Auditory steady-state responses to amplitude-modulated tones generate periodic responses in neural networks that may be accessed by means of coherence between the stimulation signal and the LFP recorded from the auditory pathway. Such signal processing methodology was applied in this work to evaluate in vivo, anaesthetized Wistar rats, activation of neural networks due to single carrier sound stimulation frequencies, as well as to evaluate the effect of different modulating tones in the evoked responses. Our results show that an inappropriate choice of sound stimuli modulating frequencies can compromise coherence analysis, e.g. misleading conclusions due to mathematical artefact of signal processing. Two modulating frequency correction protocols were used: nearest integer and nearest prime number. The nearest prime number correction was successful in avoiding spectral leakage in the coherence analysis of steady-state auditory response, as predicted by Monte Carlo simulations.

Rol de la enfermera en el servicio de neurofisiologia del Hospital Obrero N°1

El Hospital Obrero N°1 dependiente de la Caja Nacional de Salud, es una institución que presta servicio de tercer nivel, brindando atención de salud con una cobertura a nivel nacional, que en el actualidad alcanza asegurados y beneficiarios, es decir un de la población nacional, de esta manera esto representa un desafio para la enfermera profesional al retomar una de sus funciones primordiales y especificas el de la capacitación y actulización continua de acorde al avance tecnológico, en nuestra institución muy poco o casi nada se ha abordado referente a la capacitación e implementación de programas dirigidos al manejo teórico práctico en el realización de los exámenes complementarios en el servicio de Neurofisiologia, considerando todo lo anterior, el trabajo de intervención tiene como objeto capacitar al personal profesional del servicio de Neurología y Neurocirugía, en la realización de todos los exámenes Electroencefalograma, Electromiografias, Potenciales evcados, visuales, auditivos, para lograr una atención óptima de calidad al cliente esterno o interno esta capacitación se llevará a cabo en el gabinete de neurofisiología del Hospital Obrero, en el mes de octubre del presente año con una duración de una semana. para lo cual se realizará un programa de ca´pacitacióin teórico práctico

Wavelet analysis can sensitively describe dynamics of ethanol evoked local field potentials of the slug (Limax marginatus) brain.

Odorants evoke characteristic, but complex, local field potentials (LFPs) in the molluscan brain. Wavelet tools in combination with Fourier analysis can detect and characterize hitherto unknown discrete, slow potentials underlying the conspicuous oscillations. Ethanol was one of the odorants that we have extensively studied (J. Neurosci. Methods, 119 (2002) 89). To detect new features and to elucidate their functions, we tested the wavelet tools on the ethanol-evoked LFP responses of the slug (Limax) procerebrum. Recordings were made in vitro from the neuropile and the cell layer. The present study led to the following findings: (i) Mutual exclusion. Energy concentrated mainly in two ranges, (a) 0.1-0.4 Hz and (b) 1.56-12.5 Hz, and the sum of energy remained constant throughout experiments regardless of the condition. A redistribution of relative energy within this sum seemed to occur in the course of main, possible interactions between the two components excluding each other ('mutual exclusion'). (ii) Transient signal ordering and disordering. Ethanol stimulation alternatingly evoked periods of strongly time evolving oscillation dominated by the energy of 1.56-12.5 Hz (increase of entropy=disordered or complexly ordered state) and those of near-silence were predominated by the energy of 0.1-0.4 Hz (decrease of entropy=ordered state). (iii) About 0.1 Hz slow wave oscillation. It was robust. The dominant energy oscillation and the resulting large entropy fluctuation were negatively correlated to each other, and revealed strong frequency-tuning or synchronization at this frequency. Our findings suggest that discrete slow waves play functionally important roles in the invertebrate brain, as widely known in vertebrate EEG. Wavelet tools allow an easy interpretation of several minutes of frequency variations in a single display and give precise information on stimulus-evoked complex change of the neural system describing the new state 'more ordered' or 'non-ordered or more complexly ordered'.

A microcomputer program for automated neuronal spike detection and analysis.

A system for on-line spike detection and analysis based on an IBM PC/AT compatible computer, written in TURBO PASCAL 6.0 and using commercially available analog-to-digital hardware is described here. Spikes are detected by an adaptive threshold which varies as a function of signal mean and its variability. Since the threshold value is determined automatically by the signal-to-noise ratio analysis, the user is not actively involved in controlling its level. This program has been reliably used for the detection and analysis of the spike discharge of vestibular system afferent neurons. It generates the interval-joint distribution graph, the interval histogram, the autocorrelation function, the autocorrelation histogram, and phase-space graphs, thus, providing a complete set of graphical and statistical data for the characterization of the dynamics of neuronal spike activity. Data can be exported to other software such as Excel, Sigmaplot and MatLab, for example.

Estudios Electrofisiológicos en Muerte Encefálica: Electroencefalograma, Potenciales Evocados y Estudios de Conducción Nerviosa. / Electrophysiological Studies in Brain Death: Electroencephalography, Evoked potentials and Nerve conduction studies

El avance en la prestación de atención médica a pacientes, ha disminuído el número e defunciones, sin embargo, han aumentado proporcionalmente los casos en que existe preservación de las funciones biológicas básicas acompañadas de cese en el funcionamiento encefalico. A este término de muerte encefálica se le reconoce por sus características clínicas, sin embargo, se hace necesario utilizar estudios confirmatorios. En el campo de la electrofisiología, se cuenta con el Electroencefalograma, cuyo hallazgo en caso de muerte encefálica, es la ausencia de actividad cortical espontánea o provocada cuya amplitud sea mayor a 2 microvoltios en un registro de por lo menos 30 minutos. Ademas de ésta técnica ya validada por el tiempo, actualmente se han utilizado los registros de Potenciales Evocados, en los cuales existe ausencia de integración de respuestas centrales con preservación o no, de las respuestas de receptor y vías periféricas. En algunos casos, la determinación de latencias de reflejos de tallo cerebral utilizando técnicas de velocidades de conducción, pueden ser utiles al agregarlos en el protocolo. El elevado costo que conlleva el mantenimiento de un paiente en estado de muerte encefálica, así como la rapidez en llegar a determinar en los casos de posible donación de órganos, hacen necesario que las pruebas confirmatorias sean lo más fidedignas posibles, fáciles de realizar y con resultados en corto plazo, por lo cual se hace también una propuesta para la realización rutinaria del Electroencefalograma y potenciales evocados en los pacientes con sospecha de muerte encefálica.

Potenciales evocados motores. Evaluación no invasiva de la vía motora en sujetos normales y en pacientes con enfermedades neurológicas

Se presenta por primera vez en la comunidad médica nacional un estimulador eléctrico para la obtención de PEM, utilizando un aparato de diseño y fabricación local, siguiendo una línea investigativa iniciada en 1981 y mediante la cual se diseñan y construyen algunos equipos para la aplicación en neurofisiología clínica, derivada de proyectos de investigación que integran conocimientos de la instrumentación biomédica y la neurofisiología. El registro en 42 sujetos normales y la demostración de sus usos con algunos casos nos demuestran la validez y confiabilidad del instrumento fabricado. Se resalta la importancia de los PEM como método objetivo, reproducible, fácil de obtener y especialmente útil para la demostración anormalidades funcionales en la vía motora tanto central como periférica. Finalmente, se hace una revisión del tema en las que se corroboran los conocimientos sobre el estudio de la función y de las vías motoras.

Propuestas de normas de bioseguridad en la práctica neurofisiológica / A proposal for safety normams in neurophysiological practice

El SIDA y la hepatitis B son enfermedades producidas por agentes etiológicos virales que comparten las mismas vías de transmisión, a saber: el contacto sexual, el uso compartido de jeringas (drogadicción), las transfusiones y la vía transplacentaria. La probabilidad de transmisión a través de las prácticas neurofisiológicas, por el uso de electrodos de aguja o de superficie colocados sobre piel dañada, es mínima o inexistente. No obstante, dada la posibilidad potencial de la misma, el equipo de salud debe ceñirse al empleo de recomendaciones o normas de seguridad adecuadas a los fines de evitar la transmisión de paciente a paciente, así como de paciente al personal médico o técnico. Las normas propuestas contemplan la utilización de métodos de limpieza, decontaminación y esterilización de los materiales empleados, así como la forma de proceder ante casos de accidentes imprevistos. Las mismas están basadas en las Normas de Bioseguridad del Ministerio de Salud y Acción Social de la República Argentina, las guías para la prevención de la transmisión del virus de la inmunodeficiencia humana y de la hepatitis B del Centro para el Control de Enfermedades de los EE.UU. y las recomendaciones de la Academia Americana de Neurología

Propuestas de normas de bioseguridad en la práctica neurofisiológica / A proposal for safety normams in neurophysiological practice

El SIDA y la hepatitis B son enfermedades producidas por agentes etiológicos virales que comparten las mismas vías de transmisión, a saber: el contacto sexual, el uso compartido de jeringas (drogadicción), las transfusiones y la vía transplacentaria. La probabilidad de transmisión a través de las prácticas neurofisiológicas, por el uso de electrodos de aguja o de superficie colocados sobre piel dañada, es mínima o inexistente. No obstante, dada la posibilidad potencial de la misma, el equipo de salud debe ceñirse al empleo de recomendaciones o normas de seguridad adecuadas a los fines de evitar la transmisión de paciente a paciente, así como de paciente al personal médico o técnico. Las normas propuestas contemplan la utilización de métodos de limpieza, decontaminación y esterilización de los materiales empleados, así como la forma de proceder ante casos de accidentes imprevistos. Las mismas están basadas en las Normas de Bioseguridad del Ministerio de Salud y Acción Social de la República Argentina, las guías para la prevención de la transmisión del virus de la inmunodeficiencia humana y de la hepatitis B del Centro para el Control de Enfermedades de los EE.UU. y las recomendaciones de la Academia Americana de Neurología

Estudio poligráfico del sueño: parte I / Poligraphic study of sleep.Part I

This is a review of the literature in the area of poligraphic studies of sleep including modern theories on the physiological mechanisms underlyning the various sleep disorders. The simultaneous recording of electroencephalogram, electromyogram, electrocardiogram, and ocular and respiratory movements has significantly improved the research and understanding of human sleep physiology. With this technique it has been possible to identify two sleep patterns: non-REM (slow wave, quite and synchronized sleep) and REM (rapid wave active and no synchronized sleep) and to describe the physiological characteristics of each one of them. The article is illustrated with cases studied in the laboratory of electroencephalography at the San Ignacio's Hospital, Bogotá