Funding for this project was provided by the National Health and Medical Research Council (NHMRC) 1046203 (BVB, AJV) and Melbourne Neuroscience Institute Fellowship (CTN).

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</ol>

The authors have no disclosures relevant to this work.

O ERG e VEP são medidas objetivas da função visual da retina eo córtex, respectivamente. A vantagem de gravação simultânea é que uma visão mais abrangente de toda a via visual é oferecida. Especificamente, as informações complementares na sua avaliação simultânea poderia fornecer uma definição mais clara do local da lesão na via visual (por exemplo, para distúrbios com sobreposição ERG ainda distinta VEP manifestações 18, quando neuropatia óptica pode co-existir com atrofia cerebral primário 19, 20, ou quando a perda de VEP podem ser confundidos pela manifestação de lesões em vários locais na via visual 21,22). Através da medição do ERG e VEP simultaneamente, um índice do ganho entre a resposta da retina e cortical também pode ser derivada. Isto pode fornecer uma ferramenta útil para detectar alterações patológicas sutis. O protocolo atual permite a medição ERG e VEP em ratos de laboratório comumente usados, mas podem facilmente ser adApted a outras espécies de mamíferos 23-25. ERG e VEP formas de onda a partir de roedores fornecem um substituto razoável pré-clínico para respostas observadas em olhos humanos 26-28. Ao projetar um protocolo de estímulo específico, tanto resposta ERG e VEP pode ser obtida durante uma única sessão de gravação. A Tabela 1 mostra uma progressão nos níveis de luz com a devida consideração do tempo de recuperação entre flashes consecutivos. Este protocolo proporciona um equilíbrio entre a necessidade de maximizar as características sinal-ruído e limitar o tempo de gravação dentro da janela de anestésico é fornecida por uma única dose de cetamina: xilazina. Portanto, esta técnica pode ser útil para uma medida quantitativa objectivo da função visual para pesquisa em fisiologia de base e a doença. Uma avaliação abrangente do sistema visual pode ser alcançado através da avaliação simultaneamente respostas da retina bilaterais e respostas corticais visuais evocados. No entanto, cada técnica também pode ser realizada de forma isolada e monocular em vez de binocularmente para simplificar o procedimento. O protocolo atual descreve sinais escotópicas ERG e VEP escolhidos para isolar a haste da via, dado que os ratos têm uma retina dominada-rod. Se as respostas de luz adaptado são de maior interesse para o estudo, também é possível conduzir sinais ERG e VEP fotópicas por pré-adaptação a um fundo claro. Uma grande limitação desta técnica é a necessidade de realizar o procedimento em condições anestesiados para permitir a colocação do eletrodo estável. No entanto, esta abordagem fornece características robustas de sinal-para-ruído, permitindo a detecção de alterações de tratamento sutis. Devido à pequena amplitude do STR e sua sensibilidade à adaptação à luz, várias etapas devem ser cuidadosamente observados para garantir uma gravação de sucesso desta resposta. Em primeiro lugar, a adaptação ao escuro suficiente precisa ser implementado, que incluiovernight adaptação ao escuro (≥ 8 horas), a colocação do eletrodo sob iluminação vermelha fraca (17,4 cd.m -2, λ max = 600 nm), e adaptação re-escuro após um teste-flash dim (10 min para - 0,52 log cd. SM -2). Além disso, as características de sinal-para-ruído da STR pode ser melhorada pela média ao longo de vários sinais (ou seja, 20 sinais) recolhidas com intervalos curtos inter-estímulos (isto é, 2 seg). Uma das vantagens desta avaliação abrangente de ambos os olhos e córtices é permitir comparação com a gravação contralateral 3. Como tal cuidado, especial deve ser tomado na tomada de eletrodo (ou seja, os mesmos eletrodos de tamanho e em forma), para garantir o mínimo inter-olho e variabilidade inter-cortical. Dada a extensa utilização de ambas as técnicas de ERG e VEP para fornecer em medidas in vivo da via visual e os seus processos relacionados com a doença, seria útil para recolher outra via específica p-rotocols (por exemplo, ON / OFF ou cone sub-tipo específico), e realizar gravações ERG / VEP simultâneas com diferentes modalidades de estímulo (por exemplo, cintilação, teste padrão, dente de serra) para estender a aplicação desta técnica em diagnósticos clínicos. Outra etapa lógica desta aplicação no futuro também seria para gravar o ERG e VEP simultaneamente de consciência 29, os animais livremente em movimento para evitar influências anestésicos sobre a fisiologia neural 30.

Medição do eletrorretinograma (ERG) e visual potencial evocado (VEP) fornecem avaliações quantitativas úteis da integridade da via visual. O ERG mede as respostas eléctricas do retina para a estimulação pela luz, enquanto o VEP mede a integridade funcional correspondente das vias visuais da retina para o córtex visual primário seguindo o mesmo evento de luz. Este manuscrito descreve um protocolo para a gravação e análise das respostas do ERG e VEP em um modelo de laboratório comumente usado, o rato. O ERG fornece um índice da integridade funcional de um número de classes principais de células da retina quantificando resposta elétrica bruta da retina para um flash de luz. Uma série coordenada de fluxos iônicos iniciado pelo aparecimento de luz e compensar, produzir mudanças detectáveis ​​na tensão que pode ser medido por meio de eletrodos de superfície colocados fora do olho. A forma de onda resultante representa a combinação de um SEries de componentes bem definidas, diferindo na amplitude, tempo e frequência. Um corpo substancial de investigação tem demonstrado que estes componentes são relativamente bem conservada entre muitos retina de vertebrados e que os componentes podem ser separados uns dos outros. Ao seleccionar criteriosamente as condições de estímulo (stimulus flash, fundo, intervalo interstimulus) e escolher características específicas da forma de onda composta para analisar se pode ter a certeza de voltar uma medida de um grupo específico de células da retina 1,2. Estas características são a base da utilidade e, portanto, as aplicações difundidas do ERG como uma medida não-invasiva da função retina. Este manuscrito incide sobre a metodologia para a medição do ERG e analisar suas características para retornar informações sobre alguns dos principais classes de células na retina, nomeadamente fotorreceptores (o componente PIII), células bipolares (o componente PII) e células ganglionares da retina (o positivo limiar de resposta escotópica ou pstr). <p class= &quot;Jove_content&quot;&gt; O VEP proporciona um ensaio da resposta cortical à luz; primeiro proveniente da retina e posteriormente comunicadas em série através do nervo óptico, trato óptico, tálamo (núcleo geniculado lateral, LGN) e radiação óptica para a área do córtex V1 3. Em roedores, a maioria (90-95%) de fibras do nervo óptico de cada olho decussate 4 e inervam o cérebro médio contralateral. Ao contrário do ERG, é como ainda não é possível atribuir diferentes componentes da VEP às classes de células específicas, 5 muda, assim, em qualquer lugar ao longo da via visual pode afetar a forma de onda VEP. No entanto, o VEP é uma medida não-invasivo útil do desempenho visual e integridade da via visual. A VEP, quando usado em conjunto com o ERG, pode proporcionar uma avaliação mais completa do sistema visual (ou seja, a retina / via visual). registos de ERG e VEP pode ser realizada de forma isolada ou em combinação, dependendo da aplicação. A metodologia descrita neste artigo permite a avaliação simultânea de eletrofisiologia visual evocado retina e cortical de ambos os olhos e ambos os hemisférios em ratos anestesiados. Esta é uma maneira útil para avaliar de forma mais abrangente a função da retina e os efeitos a montante que as mudanças na função da retina pode ter em função cortical evocado visual.

<table><tbody><tr><td>Alligator clip</td><td>generic brand</td><td>HM3022</td><td>Stainless steel 26 mm clip for connecting VEP screw electrodes to cables</td></tr><tr><td>Bioamplifier</td><td>ADInstruments</td><td>ML 135</td><td>For amplifying ERG and VEP signals</td></tr><tr><td>Carboxymethylcellulose sodium 1.0%</td><td>Allergan</td><td>CAS 0009000-11-7</td><td>Viscous fluid for improving signal quality of the active ERG electrode</td></tr><tr><td>Carprofen 0.5%</td><td>Pfizer Animal Health Group</td><td>CAS 53716-49-7</td><td>Proprietary name: Rimadyl injectable (50 mg/ml). For post-surgery analgesia, diluted to 0.5% (5 mg/ml) in normal saline</td></tr><tr><td>Chlorhexadine 0.5%</td><td>Orion Laboratories</td><td>27411, 80085</td><td>For disinfecting surgical instruments</td></tr><tr><td>Circulating water bath</td><td>Lauda-K&amp;ouml;nigshoffen</td><td>MGW Lauda</td><td>For maintaining body temperature of the anesthetized animal during surgery and electrophysiological recordings</td></tr><tr><td>Dental amalgam</td><td>DeguDent GmbH</td><td>64020024</td><td>For encasing the electrode-skull assembly to make it more robust</td></tr><tr><td>Dental burr</td><td>Storz Instruments, Bausch and Lomb</td><td>#E0824A</td><td>A miniature drill head of ~ 0.7 mm diameter for making a small hole in the skull over each hemisphere to implant VEP screws</td></tr><tr><td>Drill</td><td>Bosch</td><td>Dremel 300 series</td><td>An automatic drill for trepanning</td></tr><tr><td>Electrode lead</td><td>Grass Telefactor&amp;nbsp;</td><td>F-E2-30</td><td>Platinum cables for connecting silver wire electrodes to the amplifier</td></tr><tr><td>Faraday Cage</td><td>custom-made</td><td></td><td>Ensures light proof to maintain dark adaptation. Encloses the Ganzfeld setup to improve signal to noise ratio</td></tr><tr><td>Gauze swabs</td><td>Multigate Medical Products Pty Ltd</td><td>57-100B</td><td>For drying the surgical incision and exposed skull surface during surgery</td></tr><tr><td>Ganzfeld integrating sphere</td><td>Photometric Solutions International</td><td></td><td>Custom designed light stimulator: 36 mm diameter, 13 cm aperture size</td></tr><tr><td>Velcro</td><td>VELCRO Australia Pty Ltd</td><td>VELCRO Brand Reusable Wrap</td><td>Hook-and-loop fastener to secure the electrodes and the animal on the recording platform</td></tr><tr><td>Isoflurane 99.9%</td><td>Abbott Australasia Pty Ltd</td><td>CAS 26675-46-7</td><td>Proprietary Name: Isoflo(TM) Inhalation anaaesthetic. Pharmaceutical-grade inhalation anesthetic mixed with oxygen gas for VEP electrode implant surgery</td></tr><tr><td>Ketamine&amp;nbsp;</td><td>Troy Laboratories</td><td>Ilium Ketamil</td><td>Proprietary name: Ketamil Injection, Brand: Ilium. Pharmaceutical-grade anesthetic for electrophysiological recording</td></tr><tr><td>Luxeon LEDs</td><td>Phillips Lighting Co.</td><td></td><td>For light stimulation twenty 5 W and one 1 W LEDs.</td></tr><tr><td>Micromanipulator</td><td>Harvard Apparatus</td><td>BS4 50-2625</td><td>Holds the ERG active electrode during recordings</td></tr><tr><td>Needle electrode</td><td>Grass Telefactor&amp;nbsp;</td><td>F-E2-30</td><td>Subcutaneously inserted in the tail to serve as the ground electrode for both the ERG and VEP</td></tr><tr><td>Phenylephrine 2.5% minims&amp;nbsp;</td><td>Bausch and Lomb</td><td>CAS 61-76-7</td><td>Instilled with Tropicamide to achieve maximal dilation for ERG recording</td></tr><tr><td>Povidone iodine 10%</td><td>Sanofi-Aventis</td><td>CAS 25655-41-8</td><td>Proprietory name: Betadine, Antiseptic to prepare the shaved skin for surgery 10%, 500 ml</td></tr><tr><td>Powerlab data acquisition system</td><td>ADInstruments</td><td>ML 785</td><td>Controls the LEDs</td></tr><tr><td>Proxymetacaine 0.5%</td><td>Alcon Laboratories&amp;nbsp;</td><td>CAS 5875-06-9</td><td>For corneal anaesthesia during ERG recordings</td></tr><tr><td>Saline solution</td><td>Gelflex</td><td></td><td>Non-injectable, for electroplating silver wire electrodes</td></tr><tr><td>Scope Software</td><td>ADInstruments</td><td>version 3.7.6</td><td>Simultaneously triggers the stimulus via the Powerlab system and collects data</td></tr><tr><td>Silver (fine round wire)</td><td>A&amp;amp;E metal</td><td>0.3 mm</td><td>Used to make active and inactive ERG electrodes, and the inactive VEP electrode</td></tr><tr><td>Stainless streel screws&amp;nbsp;</td><td>MicroFasterners</td><td></td><td>0.7 mm shaft diameter, 3 mm in length to be implanted over the primary visual cortex and serve as the active VEP electrodes</td></tr><tr><td>Stereotaxic frame</td><td>David Kopf</td><td>Model 900</td><td>A small animal stereotaxic instrument for locating the primary visual cortices according to Paxinos &amp;amp; Watson&#039;s 2007 rat brain atlas coordinates</td></tr><tr><td>Surgical blade</td><td>Swann-Morton Ltd.</td><td>0206</td><td>For incising the area of skin overlaying the primary visual cortex to implant the VEP electrodes</td></tr><tr><td>Suture</td><td>Shanghai Pudong Jinhuan Medical Products Co.,Ltd</td><td></td><td>3-0 silk braided suture non-absorbable, for skin retraction during VEP electrode implantation surgery</td></tr><tr><td>Tobramycine eye ointment 0.3%</td><td>Alcon Laboratories&amp;nbsp;</td><td>CAS 32986-56-4</td><td>Proprietary name: Tobrex. Prophylactic antibiotic ointment applied around the skin wound after surgery</td></tr><tr><td>Tropicamide 0.5%</td><td>Alcon Laboratories&amp;nbsp;</td><td>CAS 1508-75-4</td><td>Proprietary name: 0.5% Mydriacyl eye drop, Instilled to achieve mydriasis for ERG recording</td></tr><tr><td>Xylazine</td><td>Troy Laboratories</td><td>Ilium Xylazil-100</td><td>Pharmaceutical-grade anesthetic for electrophysiological recording</td></tr><tr><td>Pipette tip</td><td>Eppendorf Pty Ltd</td><td>0030 073.169</td><td>Eppendorf epTIPS 100 - 5,000 ml, for custom-made electrodes</td></tr><tr><td>Microsoft Office Excel</td><td>Microsoft</td><td>version 2010</td><td>spreadsheet software for data analysis</td></tr><tr><td>Lethabarb Euthanazia Injection</td><td>Virbac (Australia) Pty Ltd</td><td>LETHA450</td><td>325 mg/ml pentobarbital sodium for rapid euthanazia</td></tr></tbody></table>

simultaneous recording of electroretinography and visual evoked potentials in anesthetized rats

The electroretinogram (ERG) and visual evoked potential (VEP) are commonly used to assess the integrity of the visual pathway. The ERG measures the electrical responses of the retina to light stimulation, while the VEP measures the corresponding functional integrity of the visual pathways from the retina to the primary visual cortex following the same light event. The ERG waveform can be broken down into components that reflect responses from different retinal neuronal and glial cell classes. The early components of the VEP waveform represent the integrity of the optic nerve and higher cortical centers. These recordings can be conducted in isolation or together, depending on the application. The methodology described in this paper allows simultaneous assessment of retinal and cortical visual evoked electrophysiology from both eyes and both hemispheres. This is a useful way to more comprehensively assess retinal function and the upstream effects that changes in retinal function can have on visual evoked cortical function.

O ERG uma onda (&gt; -1,38 log cd.sm -2), b-ondas (&gt; - 4,99 log cd.sm -2) STRs (&lt;- 4,99 log cd.sm -2) e os PEVs (&gt; - 0,52 cd.sm log -2) foram gravadas simultaneamente (Figura 1 e 3). No flashes muito fraca, a STR positivo (pstr) é visto em cerca de 110 milissegundos após o flash, e uma STR negativo (NSTR) a cerca de 220 ​​ms (Figuras 1 e 2). Um ERG com um grande da onda b, picos entre 50 a 100 ms após o início de um flash moderada que podem ser analisados ​​para a sua resposta PII (Figuras 1 e 2). Neste energia estímulo, o negativo de uma onda antes do pico é insignificante. A energias luminosas brilhantes a deformação negativa da onda torna-se mais proeminente que pode ser quantificado com a resposta PIII (Figura 2). A forma de onda escotópica VEP mostra uma resposta negativa (P1N1; 15-70 janela mseg) seguido de<html> um desvio positivo (N1P2; 30 - 100 ms) (Figuras 3 e 4). <img alt="figura 1" src="/files/ftp_upload/54158/54158fig1.jpg" /> Figura 1. Grupo Média ERG formas de onda. O ERG altera com o aumento da intensidade do estímulo. Os números à esquerda da forma de onda indicar a exposição luminosa utilizada para induzir a forma de onda. Observe as diferentes escalas de amplitude e tempo para cada painel. A energias luminosas de intensidade da luz das componentes positiva e negativa da resposta escotópica limiar pode ser provocada (pStr, NSTR). Como energias estímulo ficar mais brilhante, a um e b-onda de resposta pode ser testada, e um paradigma-flash emparelhado permite que a resposta cone a ser medido. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54158/54158fig1large.jpg" target="_blank">Por favor clique aqui para ver uma versão maior desta figura.</a> pload / 54158 / 54158fig2.jpg &quot;/&gt; Figura 2. Análise. (A) A função de fotorreceptores Rod ERG pode ser ensaiada usando um PIII para modelar a uma onda. A-ondas na cd.sm 1,22 e 1,52 log -2 (círculos não preenchidas, ○) estão aptos como um conjunto com um PIII (linhas cinzentas, Equação 1) a 90% do mínimo que retorna Rm PIII (amplitude saturado, mV) S (sensibilidade, m 2 .s -1 .cd -3) e os parâmetros de TD (atraso de temporização, ms). (B) a função da célula bipolar haste (média ± SEM) pode ser ensaiada através da modelação da série resposta intensidade da haste PII (círculos não preenchidos ○) com uma função de Naka-Rushton (linha cinza). Isso retorna V max (amplitude saturado, mV), k (1 / sensibilidade, ingresse cd sm -2) e n (inclinação). Função de células ganglionares (C) Retinal é ensaiada em energias luminosas fracas e quantificados por pstr pico de amplitude (pstr amp) e tempo (pstr-lo </sub&gt;). (D) a função das células bipolar Cone é provocada com um paradigma-flash emparelhado quantificada por cone PII pico de amplitude (cone PII amp) e tempo (cone PII-lo). <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54158/54158fig2large.jpg" target="_blank">Por favor clique aqui para ver uma versão maior desta figura.</a> <img alt="Figura 3" src="/files/ftp_upload/54158/54158fig3.jpg" /> Figura 3. Grupo Média VEP formas de onda. A forma da onda de VEP altera com o aumento da energia estímulo. Os números à esquerda da forma de onda indicam a exposição luminosa utilizada para induzir a forma de onda. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54158/54158fig3large.jpg" target="_blank">Por favor clique aqui para ver uma versão maior desta figura.</a> <img alt="Figura 4" src="/files/ftp_upload/54158/54158fig4.jpg" /> Figure 4. Análise VEP e função Response Intensidade. (A) Análise Amplitude da VEP é tomado como pico à calha (P1N1) e através de pico amplitudes (N1P2). Os tempos implícitos (ele) destas respostas também é retornado (P1-lo, N1-lo, P2-lo). (B) A amplitude VEP P1N1 (média ± SEM) aumenta com o aumento da energia estímulo. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54158/54158fig4large.jpg" target="_blank">Por favor clique aqui para ver uma versão maior esta figura.</a>

Watch this Scientific Journal Video about Simultaneous Recording of Electroretinography and Visual Evoked Potentials in Anesthetized Rats at JoVE.com

Simultaneous Recording of Electroretinography and Visual Evoked Potentials in Anesthetized Rats

This protocol describes simultaneous measurement of electroretinogram and visual evoked potentials in anesthetized rats.

Gravação simultânea de Eletrorretinografia e potenciais evocados visuais em ratos anestesiados

The electroretinogram (ERG) and visual evoked potential (VEP) are commonly used to assess the integrity of the visual pathway. The ERG measures the ...

simultaneous-recording-electroretinography-visual-evoked-potentials

Nanyang Technological University

Research

JoVE Journal

Neuroscience

12.3K visualizações.  University of Melbourne. This protocol describes simultaneous measurement of electroretinogram and visual evoked potentials in anesthetized rats. 

Vídeo: Simultaneous Recording of Electroretinography and Visual Evoked Potentials in Anesthetized Rats

Implantation and Recording of Wireless Electroretinogram and Visual Evoked Potential in Conscious Rats

The full-field electroretinogram (ERG) and visual evoked potential (VEP) are useful tools to assess retinal and visual pathway integrity in both laboratory and clinical settings. Currently, preclinical ERG and VEP measurements are performed with anesthesia to ensure stable electrode placements. However, the very presence of anesthesia has been shown to contaminate normal physiological responses. To overcome these anesthesia confounds, we develop a novel platform to assay ERG and VEP in conscious rats. Electrodes are surgically implanted sub-conjunctivally on the eye to assay the ERG and epidurally over the visual cortex to measure the VEP. A range of amplitude and sensitivity/timing parameters are assayed for both the ERG and VEP at increasing luminous energies. The ERG and VEP signals are shown to be stable and repeatable for at least 4 weeks post surgical implantation. This ability to record ERG and VEP signals without anesthesia confounds in the preclinical setting should provide superior translation to clinical data.

We show surgical implantation and Recording procedures to measure visual electrophysiological signals from the eye (electroretinogram) and brain (visual evoked potential) in conscious rats, which is more analogous to the human condition where recordings are conducted without anesthesia confounds.

Implantação e Gravação do Wireless Eletrorretinograma e Visual Potencial Evocado em ratos conscientes

The full-field electroretinogram (ERG) and visual evoked potential (VEP) are useful tools to assess retinal and visual pathway integrity in both ...

Comportamento

Using the Electroretinogram to Assess Function in the Rodent Retina and the Protective Effects of Remote Limb Ischemic Preconditioning

The ERG is the sum of all retinal activity. The ERG is usually recorded from the cornea, which acts as an antenna that collects and sums signals from the retina. The ERG is a sensitive measure of changes in retinal function that are pan-retinal, but is less effective for detecting damage confined to a small area of retina. In the present work we describe how to record the &#8216;flash&#8217; ERG, which is the potential generated when the retina is exposed to a brief light flash. We describe methods of anaesthesia, mydriasis and corneal management during recording; how to keep the retina dark adapted; electrode materials and placement; the range and calibration of stimulus energy; recording parameters and the extraction of data. We also describe a method of inducing ischemia in one limb, and how to use the ERG to assess the effects of this remote-from-the-retina ischemia on retinal function after light damage. A two-flash protocol is described which allows isolation of the cone-driven component of the dark-adapted ERG, and thereby the separation of the rod and cone components. Because it can be recorded with techniques that are minimally invasive, the ERG has been widely used in studies of the physiology, pharmacology and toxicology of the retina. We describe one example of this usefulness, in which the ERG is used to assess the function of the light-damaged retina, with and without a neuroprotective intervention; preconditioning by remote ischemia.

The electroretinogram (ERG) is an electrical potential generated by the retina in response to light. This paper describes how to use the ERG to assess retinal function, in dark-adapted rats, and how it can be can be used to assess a neuroprotective intervention, in the present case remote ischemic preconditioning.

Usando o Eletrorretinograma na Avaliação da Função na Roedor Retina e os efeitos protetores do remoto Limb Pré-Condicionamento Isquêmico

The ERG is the sum of all retinal activity. The ERG is usually recorded from the cornea, which acts as an antenna that collects and sums signals from the ...

Neurociência

Visual Evoked Potential Recording in a Rat Model of Experimental Optic Nerve Demyelination

The visual evoked potential (VEP) recording is widely used in clinical practice to assess the severity of optic neuritis in its acute phase, and to monitor the disease course in the follow-up period. Changes in the VEP parameters closely correlate with pathological damage in the optic nerve. This protocol provides a detailed description about the rodent model of optic nerve microinjection, in which a partial demyelination lesion is produced in the optic nerve. VEP recording techniques are also discussed. Using skull implanted electrodes, we are able to acquire reproducible intra-session and between-session VEP traces. VEPs can be recorded on individual animals over a period of time to assess the functional changes in the optic nerve longitudinally. The optic nerve demyelination model, in conjunction with the VEP recording protocol, provides a tool to investigate the disease processes associated with demyelination and remyelination, and can potentially be employed to evaluate the effects of new remyelinating drugs or neuroprotective therapies.

Focal demyelination is induced in the optic nerve using lysolecithin microinjection. Visual evoked potentials are recorded via skull electrodes implanted over the visual cortex to examine the signal conduction along the visual pathway in vivo. This protocol details the surgical procedures underlying electrode implantation and optic nerve microinjection.

Visual Gravação Potencial Evocado em um modelo de rato de Experimental Nervo Óptico desmielinização

The visual evoked potential (VEP) recording is widely used in clinical practice to assess the severity of optic neuritis in its acute phase, and to ...

Concurrent Recording of Co-localized Electroencephalography and Local Field Potential in Rodent

Although electroencephalography (EEG) is widely used as a non-invasive technique for recording neural activities of the brain, our understanding of the neurogenesis of EEG is still very limited. Local field potentials (LFPs) recorded via a multi-laminar microelectrode can provide a more detailed account of simultaneous neural activity across different cortical layers in the neocortex, but the technique is invasive. Combining EEG and LFP measurements in a pre-clinical model can greatly enhance understanding of the neural mechanisms involved in the generation of EEG signals, and facilitate the derivation of a more realistic and biologically accurate mathematical model of EEG. A simple procedure for acquiring concurrent and co-localized EEG and multi-laminar LFP signals in the anesthetized rodent is presented here. We also investigated whether EEG signals were significantly affected by a burr hole drilled in the skull for the insertion of a microelectrode. Our results suggest that the burr hole has a negligible impact on EEG recordings.

This protocol describes a simple method for concurrent recording of co-localized electroencephalography (EEG) and multi-laminar local field potential in an anesthetized rat. A burr hole drilled in the skull for the insertion of a microelectrode is shown to produce negligible distortion of the EEG signal.

Gravação simultânea de eletroencefalografia co localizada e potencial do campo Local em roedores

Although electroencephalography (EEG) is widely used as a non-invasive technique for recording neural activities of the brain, our understanding of the ...

Electroretinogram Recording for Infants and Children under Anesthesia to Achieve Optimal Dark Adaptation and International Standards

Electroretinogram (ERG) is the only clinical objective test available to assess retinal function. Full-field ERG (ffERG) measures the panretinal rod and cone photoreceptor function as well as inner retinal function and is an important measure in the diagnosis and management of inherited retinal diseases as well as inflammatory, toxic, and nutritional retinopathies. Adhering to international standards and maintaining retinal dark adaptation are critical to acquire valid and reliable dark-adapted (scotopic) and light-adapted (photopic) ffERG responses. Performing ffERG in infants and children is challenging and often requires general anesthesia in the operating room. However, maintaining retinal dark adaptation in the operating room is becoming increasingly difficult given the numerous light sources from anesthesiology monitoring systems and other equipment. A practical and widely applicable method for ffERG testing is described in the operating room that optimizes retinal dark adaptation. The method reduces operating room time by dark-adapting the patient before general anesthesiology is instituted. The operating room is modified for dark adaptation and any remaining light source in the darkened operating room is minimized with the use of a modified portable foldable darkroom that encloses the patient&#8217;s head and the ERG examiner during ffERG scotopic recordings. The simple method adheres to ffERG international standards and provides valid reliable scotopic and photopic ffERG recordings that are critical to assess objective retinal function in this young age group where subjective assessment of visual function such as visual acuity and visual fields are not possible. Furthermore, the ffERG is the gold standard clinical test in detecting early onset inherited retinal diseases including Leber congenital amaurosis where approved gene therapy has become available. In sedated conditions, very low amplitude ffERG signals can be detected due to minimal orbicularis muscle activity interference, which is particularly relevant in patients after gene therapy to detect improved amplitude responses.

Adhering to international standards and maintaining retinal dark adaptation are critical to acquire valid full-field electroretinogram responses in the diagnosis and management of inherited retinal diseases. A practical protocol using a portable darkroom is provided to obtain full-field&#160;electroretinogram for infants and children under sedation or general anesthesia in the operating room setting.

Gravação de eletroretinograma para bebês e crianças sob anestesia para alcançar adaptação escura ideal e padrões internacionais

Electroretinogram (ERG) is the only clinical objective test available to assess retinal function. Full-field ERG (ffERG) measures the panretinal rod and ...

Medicina

Full-Circle Cauterization of Limbal Vascular Plexus for Surgically Induced Glaucoma in Rodents

Glaucoma, the second leading cause of blindness worldwide, is a heterogeneous group of ocular disorders characterized by structural damage to the optic nerve and retinal ganglion cell (RGC) degeneration, resulting in visual dysfunction by interrupting the transmission of visual information from the eye to the brain. Elevated intraocular pressure is the most important risk factor; thus, several models of ocular hypertension have been developed in rodents by either genetic or experimental approaches to investigate the causes and effects of the disease. Among those, some limitations have been reported such as surgical invasiveness, inadequate functional assessment, requirement of extensive training, and highly variable extension of retinal damage. The present work characterizes a simple, low-cost, and efficient method to induce ocular hypertension in rodents, based on low-temperature, full-circle cauterization of the limbal vascular plexus, a major component of aqueous humor drainage. The new model provides a technically easy, noninvasive, and reproducible subacute ocular hypertension, associated with progressive RGC and optic nerve degeneration, and a unique post-operative clinical recovery rate that allows in vivo functional studies by both electrophysiological and behavioral methods.

The goal of this protocol is to characterize a novel model of glaucomatous neurodegeneration based on 360&#176; thermic cauterization of limbal vascular plexus, inducing subacute ocular hypertension.

Cauterização em círculo completo do plexo vascular limbal no glaucoma induzido cirurgicamente em roedores

Glaucoma, the second leading cause of blindness worldwide, is a heterogeneous group of ocular disorders characterized by structural damage to the optic ...

Preparing a Rat Model to Assess Visual Pathway Integrity Using an Electrophysiology Setup

Source: Nguyen, C. T. et al., <a href="https://app-jove-com.remotexs.ntu.edu.sg/v/54158">Simultaneous Recording of Electroretinography and Visual Evoked Potentials in Anesthetized Rats.</a>&#160;J. Vis. Exp. (2016)
This video demonstrates the preparation of a rat model to study retinal health and visual pathway integrity. Visual evoked potential and electroretinography reference and active electrodes are connected to the rat, followed by aligning the platform with the rat in front of the Ganzfeld bowl for even retinal illumination and closing the Faraday cage to avoid external interference.

Preparando um modelo de rato para avaliar a integridade da via visual usando uma configuração de eletrofisiologia

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
1. ...

JoVE Encyclopedia of Experiments

Neurophysiology

Electrophysiology Techniques

Direct-Coupled Electroretinogram Recording of the Retinal Pigment Epithelium in a Mouse

Source: Miyagishima, K. J., et al. <a href="https://app-jove-com.remotexs.ntu.edu.sg/v/61491">Direct-Coupled Electroretinogram (DC-ERG) for Recording the Light-Evoked Electrical Responses of the Mouse Retinal Pigment Epithelium.</a> J. Vis. Exp. (2020).
This video demonstrates the recording of a direct-coupled electroretinogram (DC-ERG) on a dark-adapted, anesthetized mouse retinal pigment epithelium (RPE). After applying dilating drops, the animal is placed in a recording setup, and the capillary electrode filled with a salt buffer is placed on the cornea. After establishing the baseline, DC-ERG is recorded.

Registro de eletrorretinograma acoplado direto do epitélio pigmentar da retina em um camundongo

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
1. Mouse ...

Imaging and Optical Techniques

Recording of Visual Evoked Potentials via the Skull Electrodes in a Rat Model

Source: You, Y., et al. <a href="https://app-jove-com.remotexs.ntu.edu.sg/v/52934">Visual Evoked Potential Recording in a Rat Model of Experimental Optic Nerve Demyelination.</a> J. Vis. Exp. (2015).
This video demonstrates the process of measuring visual evoked potentials or VEPs in a dark-adapted, anesthetized rat with pre-implanted skull electrodes, which record the electrical signals from the brain&#39;s visual cortex in response to light stimuli.

Registro de potenciais evocados visuais através dos eletrodos do crânio em um modelo de rato

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
1. VEP ...

Concurrent Electroencephalographic and Local Field Potential Recordings in an Anesthetized Rat

Source: Kang, S., et al. <a href="https://app-jove-com.remotexs.ntu.edu.sg/v/56447">Concurrent Recording of Co-localized Electroencephalography and Local Field Potential in Rodent.</a> J. Vis. Exp. (2017).
This video demonstrates the procedure for concurrent recordings of co-localized electroencephalography (EEG) and local field potentials (LFPs) in an anesthetized rat. The process involves preparing the rat and attaching stimulating electrodes to its whisker pads. An EEG spider electrode is placed on the rat&#39;s skull for surface EEG measurements. At the same time, a multi-channel microelectrode is inserted into a specific brain region through a burr hole in the skull to record neural activity from a localized brain area.