Este estudo foi apoiado pelo Instituto de Pesquisa Oftalmológica da Austrália (ORIA). Agradecemos Prof. Algis Vingrys e Dr. estrondo Bui, da Universidade de Melbourne, inicialmente para ajudar-nos a desenvolver a técnica de gravação VEP.

Declaração de Ética: Todos os procedimentos envolvendo animais foram conduzidos de acordo com o Código de Prática australiano para o Cuidado e Utilização de animais para fins científicos e as diretrizes da Declaração ARVO para o Uso de Animais em Oftalmologia e Vision Research, e foram aprovadas pelo Comitê de Ética Animal da Universidade Macquarie. 1. VEP Eletrodo Implantação <ol><li> Anestesiar o animal com uma injecção intraperitoneal de cetamina (75 mg / kg) e medetomidina (0,5 mg / kg). Nota: Após a indução da anestesia, observar os reflexos de retirada (teste beliscão, reflexos da córnea e da pálpebra, etc.) e sua ausência como uma indicação para começar a cirurgia. Continuamente monitorar animais durante toda a cirurgia e administrar anestésico adicional (10% da dose inicial por cetamina top-up), se os reflexos estão presentes. Ratos adultos (&gt; 12 semanas) são utilizados nas experiências. </li><li> Raspar a pele da área cirúrgica.Colocar o animal numa almofada de aquecimento (37 ° C) para manter a temperatura do corpo durante a cirurgia. Prepare a pele através da aplicação tópica de povidona-iodo. Aplicar drapeados cirúrgico. Aplicar pomada oftálmica tópica para prevenir o ressecamento da córnea sob anestesia geral. Manter assepsia utilizando instrumentos esterilizados. </li><li> Faça uma incisão cutânea longitudinal na linha média da pele cabeça. Limpar o tecido conjuntivo para conseguir uma boa exposição do crânio. </li><li> Cuidadosamente, perfurar pequenos buracos burr manualmente usando uma broca de micro mão em 7 mm para trás do bregma e 3 mm lateral à linha média. </li><li> Eléctrodos de parafuso do implante através do crânio para o córtex (zona 17), que penetram no córtex a uma profundidade de aproximadamente 0,5 mm. Implantar um eletrodo parafuso de referência na linha média 3 mm rostral do bregma. Aplique o cimento dental para envolver e fixar os parafusos (nem sempre necessário). </li><li> Suturar a pele da cabeça, administrar pomada antibiótica na pele e permitir que o animal recover da anestesia em uma almofada de aquecimento. Nota: Em alternativa, os eléctrodos podem ser deixada exposta, de forma que a pele não precisa ser reaberto em cada gravação. Imediatamente após a cessação da cirurgia, mas antes da recuperação da anestesia, administrar uma droga não-esteróide anti-inflamatório (NSAID) (se não for administrado no período pré-operatório), ou um analgésico opióide. Monitorar os animais constantemente até a recuperação completa de anestésico e totalmente ambulatorial. </li><li> Permitir que pelo menos uma semana para os animais para se recuperar da cirurgia antes da gravação VEP. </li></ol> 2. Optic Nerve Injeção <ol><li> Anestesiar o animal, preparar a pele e aplicar drapejar como acima (1.1 e 1.2). </li><li> Adicione um, de 1 a 1,5 cm de incisão na pele acima da órbita de um olho seleccionada aleatoriamente. Abra o tecido subcutâneo para alcançar a cavidade orbital usando íris tesoura fina. Abra a conjuntiva e anterior da cápsula de Tenon sob o microscópio de operação. </li><li> Retrair o extraocularmúsculos e as glândulas lacrimais intraobital para expor aproximadamente 3 mm de comprimento do nervo óptico. Abra as camadas da dura e matéria aracnóide ao redor do nervo óptico longitudinalmente usando uma lâmina oftalmológica. </li><li> Inserir a pipeta de vidro para o nervo óptico a uma distância de 2 mm posterior ao globo. A micropipeta de vidro é ligada a uma seringa Hamilton. </li><li> Injectar 1% lisolecitina (0,4-1,0 mL, com 0,02% de azul de Evan, que não tem efeitos sobre a mielinização) lentamente no nervo aproximadamente ao longo de um período de 30 seg. </li><li> Suturar a incisão na pele. Aplicar pomada antibiótica para prevenir a infecção. Olhos do companheiro pode ser servido como controles internos para gravações de eletrofisiologia. </li><li> Colocar os animais numa almofada de aquecimento para recuperar da anestesia. </li></ol> 3. VEP Recording <ol><li> Anestesiar o animal e preparar a pele como 1.1 e 1.2. Nota: Baixa dose de anestésico pode ser utilizado para reco electrofisiológicording (cetamina 40 mg / kg de medetomidina e 0,25 mg / kg). </li><li> Coloque o rato em um quarto escuro e deixe-a adaptar-se à escuridão por 5-30 min. Em alguns casos os ratos podem respectivamente ser escuro O adaptados / N para scotopic ou luz adequada para gravações photopic VEP 8. </li><li> Manter a temperatura do corpo a 37 ± 0,5 ° C, segundo o sistema de cobertor Homeotérmica com uma sonda do termómetro rectal. </li><li> Dilatar as pupilas com 1,0% tropicamide colírio. Abra a pele sobre o crânio para aceder ao pré-colocada em eléctrodos de parafuso situ. </li><li> Ligar o parafuso ao longo do córtex visual do olho contralateral estimulada e o parafuso de referência para o amplificador. Insira um eletrodo de agulha na cauda como o chão. Medir e manter a impedância do eléctrodo inferior a 5 kW. </li><li> Coloque um estimulador mini-Ganzfeld diretamente sobre a pele ao redor das pálpebras para fornecer isolamento superior de olho 7. A iluminação do estimulador necessita de ser calibrado de antemãopor um fotómetro. </li><li> Entregar fotostimulação através de flashes de luz 100 vezes a uma frequência de 1 Hz, com configurações de filtro passa-banda de baixa e alta de 1 e 100 Hz, respectivamente. A taxa de amostragem de sinal é a 5 kHz. Nota: devem ser sujeitos a amostragem Sinais de, pelo menos, a cerca de 250-300 Hz para assegurar que mais que duas amostras são recolhidas durante cada ciclo. </li><li> Suturar a pele para trás e manter os animais em uma almofada de aquecimento para se recuperar da anestesia. A gravação pode ser repetidamente gravado em animais individuais para monitorar as alterações funcionais ao longo de um período de tempo. </li><li> No ponto final, administrar uma injecção sobredosagem de pentobarbitona de sódio (100 mg / kg, ip) de sacrificar o animal. Confirme a eutanásia por parada cardíaca, parada respiratória e diminuição da temperatura corporal. </li></ol> 4. Preparação de tecidos e Histologia <ol><li> Remova os nervos ópticos de animais sacrificados sob o microscópio e fixar o tecido em paraformaldeído 1% O / N. </li> &lt;li&gt; Lavar cuidadosamente o tecido com solução salina. Tratar o tecido em um processador de tecido automático e incorporar em parafina. Seções de corte (5-10 um) usando um micrótomo rotativo. Nota: Para o estudo imuno-histoquímica, fixar o tecido em paraformaldeído a 1%, lavou-se com solução salina e incubar com 30% de sacarose S / N. Tecido incorporar em outubro incorporação médio e fazer criosecções usando um criostato. </li><li> Incubar seções em 0,1% rápida solução de azul, como Luxol (em 95% de etanol) O / N a 56 ° C. Diferenciar as secções em 0,05% de carbonato de lítio durante 30 seg e em seguida etanol a 70% durante mais 30 seg. Finalmente, contracoloração em solução violeta de cresilo a 0,1% durante 30 s antes de montar as secções. Utilizar a coloração com azul rápido para identificar mielina no nervo óptico 5. </li></ol>

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	<li>Balcer, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+practice.+Optic+neuritis.">Clinical practice. Optic neuritis.</a> N Engl J Med. 354 (12), 1273-1280 (2006).</li><li>Lassmann, H., Waxman, S. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Multiple sclerosis as a neuronal disease. , 153-164 (2005).</li><li>Fahle, M., Bach, M., Heckenlively, J., Arden, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Principles and practice of clinical electrophysiology of vision. , 207-234 (2006).</li><li>Halliday, A. M., McDonald, W. 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None of the authors have competing interests or conflicting interests.

The optic nerve is very susceptible to mechanical damage. Optic nerve crush injury over a duration of 1 s can lead to about 75% loss of RGC over a period of 2 weeks10. Therefore, extreme care is required while performing the surgical procedures. According to the authors&#8217; experience, it is much better to adapt a blunt dissection approach to expose and make way through the tissues around the optic nerve along the orientation of the nerve, rather than penetrating in a perpendicular orientation to the optic ...

Optic neuritis is one of the most common form of optic neuropathy, causing complete or partial loss of vision1. Histologically, it is featured by inflammatory demyelination, retinal ganglion cell axonal loss and varying degrees of remyelination in the optic nerve2. Optic neuritis is usually the manifest onset of multiple sclerosis. The visual evoked potential (VEP) is a non-invasive tool for investigating the function of the visual system. It reflects the post-retinal function from the retina to the primary visual cortex and is affected in many optic nerve disease conditions3. The VEP has been predominantly used in optic neuritis patients to assess the integrity of the visual pathway4. 
The latency of VEP, which reflects the velocity of signal conduction along the visual pathway, is considered to be an accurate measurement of the level of myelin associated changes in the optic nerve5; while the amplitude of VEP is believed to be closely correlated with axonal damage of the retinal ganglion cells (RGC)6. This hypothesis has been fairly well established using the rat model of lysolecithin-induced optic nerve demyelination5. 
Here, we explicate a comprehensive protocol of optic nerve microinjection technique in rodents, which can minimise the surgical manipulation-related damage to the nerve per se as well as to the adjacent tissues such as extraocular muscles and blood vessels. Also, the skull electrode implantation surgery has been described for VEP recording in animals7. The VEP recordings can be repeatedly carried out on animals over a period of time to assess demyelination/remyelination related changes as well as impact on axonal integrity in the optic nerve.

<table><tbody><tr><td>Ketamine 100 mg/ml (Ketamil)</td><td>Troy Laboratories</td><td>AC 116</td><td></td></tr><tr><td>Medetomidine 1 mg/ml (Domitor)</td><td>Pfizer</td><td>sc-204073</td><td></td></tr><tr><td>Tropicamide 1.0% (Mydriacyl)</td><td>Alcon</td><td>sc-202371</td><td></td></tr><tr><td>Homoeothermic blanket system</td><td>Harvard Apparatus</td><td>NC9203819</td><td></td></tr><tr><td>Impedance meter&amp;nbsp;</td><td>Grass</td><td>F-EZM5</td><td></td></tr><tr><td>Screw electrodes&amp;nbsp;</td><td>Micro Fasteners</td><td>M1.0&amp;times;3mm Csk Slot M/T 304 S/S</td><td></td></tr><tr><td>Subdermal needle electrodes&amp;nbsp;</td><td>Grass</td><td>F-E3M-72</td><td></td></tr><tr><td>Rapid Repair&amp;nbsp;</td><td>DeguDent GmbH</td><td></td><td></td></tr><tr><td>Light-emitting diode&amp;nbsp;</td><td>Nichia</td><td>NSPG300A</td><td></td></tr><tr><td>Bioamplifier</td><td>CWE, Inc.</td><td>BMA-400</td><td></td></tr><tr><td>CED system</td><td>Cambridge Electronic Design, Ltd.</td><td>Power1401</td><td></td></tr><tr><td>Hamilton syringe&amp;nbsp;</td><td>Hamilton</td><td>87930</td><td></td></tr><tr><td>Lysolecithin</td><td>Sigma</td><td>L4129</td><td></td></tr><tr><td>Evan&amp;rsquo;s blue&amp;nbsp;</td><td>Sigma</td><td>E2129</td><td></td></tr></tbody></table>

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.

Vestígios VEP intra-sessões reprodutíveis são mostrados na Figura 1 e um atraso significativo na latência N1 pode ser visto depois da injecção do nervo óptico. Lesões do nervo óptico parciais de desmielinização pode ser observado em secções histológicas utilizando coloração com azul rápido Luxol 5. A Figura 2 mostra uma secção representativa com uma pequena lesão demyelinated focal no centro do nervo óptico. Note-se que a secção transversal não repres...

Watch this Scientific Journal Video about Visual Evoked Potential Recording in a Rat Model of Experimental Optic Nerve Demyelination at JoVE.com

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

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 ...

visual-evoked-potential-recording-rat-model-experimental-optic-nerve

Universidad de Cartagena UDEC

Research

JoVE Journal

Neuroscience

12.2K visualizações.  Macquarie University. 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. 

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

Single-unit In vivo Recordings from the Optic Chiasm of Rat

Information about the visual world is transmitted to the brain in sequences of action potentials in retinal ganglion cell axons that make up the optic nerve. In vivo recordings of ganglion cell spike trains in several animal models have revealed much of what is known about how the early visual system processes and encodes visual information. However, such recordings have been rare in one of the most common animal models, the rat, possibly owing to difficulty in detecting spikes fired by small diameter axons. The many retinal disease models involving rats motivate a need for characterizing the functional properties of ganglion cells without disturbing the eye, as with intraocular or in vitro recordings. Here, we demonstrate a method for recording ganglion cell spike trains from the optic chiasm of the anesthetized rat. We first show how to fabricate tungsten-in-glass electrodes that can pick up electrical activity from single ganglion cell axons in rat. The electrodes outperform all commercial ones that we have tried. We then illustrate our custom-designed stereotaxic system for in vivo visual neurophysiology experiments and our procedures for animal preparation and reliable and stable electrode placement in the optic chiasm.

Single-unit In vivo Recordings from the Optic Chiasm of Rat

Retinal ganglion cells transmit visual information from the eye to the brain with sequences of action potentials. Here, we demonstrate how to record the action potentials of single ganglion cells in vivo from anesthetized rats.

Única unidade de In vivo Gravações do quiasma óptico de rato

Information about the visual world is transmitted to the brain in sequences of action potentials in retinal ganglion cell axons that make up the optic ...

Neurociência

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

Rat Model of Photochemically-Induced Posterior Ischemic Optic Neuropathy

Posterior Ischemic optic neuropathy (PION) is a sight-devastating disease in clinical practice. However, its pathogenesis and natural history have&#160;remained poorly understood. Recently, we developed a reliable, reproducible animal model of PION and tested the treatment effect of some neurotrophic factors in this model1. The purpose of this video is to demonstrate our photochemically induced model of posterior ischemic optic neuropathy, and to evaluate its effects with retrograde labeling of retinal ganglion cells. Following surgical exposure of the posterior optic nerve, a photosensitizing dye, erythrosin B, is intravenously injected and a laser beam is focused onto the optic nerve surface. Photochemical interaction of erythrosin B and the laser during irradiation damages the vascular endothelium, prompting microvascular occlusion mediated by platelet thrombosis and edematous compression. The resulting ischemic injury yields a gradual but pronounced retinal ganglion cell dieback, owing to a loss of axonal input - a remote, injury-induced and clinically relevant outcome. Thus, this model provides a novel platform to study the pathophysiologic course of PION,&#160;and can be further optimized for testing therapeutic approaches for optic neuropathies as well as other CNS ischemic diseases.

The goal of this protocol is to photochemically induce ischemic injury to the posterior optic nerve in rat. This model is critical to studies of the pathophysiology of posterior ischemic optic neuropathy, and therapeutic approaches for this and other optic neuropathies, as well as of other CNS ischemic diseases.

Modelo de Rato Induzida fotoquimicamente posterior neuropatia óptica isquémica

Posterior Ischemic optic neuropathy (PION) is a sight-devastating disease in clinical practice. However, its pathogenesis and natural history ...

Medicina

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.

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 ...

Visual Evoked Potential Recordings in Mice Using a Dry Non-invasive Multi-channel Scalp EEG Sensor

For scalp EEG research environments with laboratory mice, we designed a dry-type 16 channel EEG sensor which is non-invasive, deformable, and re-usable because of the plunger-spring-barrel structural facet and mechanical strengths resulting from metal materials. The whole process for acquiring the VEP responses in vivo from a mouse consists of four steps: (1) sensor assembly, (2) animal preparation, (3) VEP measurement, and (4) signal processing. This paper presents representative measurements of VEP responses from multiple mice with a submicro-voltage signal resolution and sub-hundred millisecond temporal resolution. Although the proposed method is safer and more convenient compared to other previously reported animal EEG acquiring methods, there are remaining issues including how to enhance the signal-to-noise ratio and how to apply this technique with freely moving animals. The proposed method utilizes easily available resources and shows a repetitive VEP response with a satisfactory signal quality. Therefore, this method could be utilized for longitudinal experimental studies and reliable translational research exploiting non-invasive paradigms.

We designed a dry-type 16 channel EEG sensor which is non-invasive, deformable, and re-usable. This paper describes the whole process from manufacturing the proposed EEG electrode to signal processing of visual evoked potential (VEP) signals measured on a mouse scalp using a dry non-invasive multi-channel EEG sensor.

Gravações de potenciais evocadas visuais em ratos usando um não-invasivo seco multi-canal do couro cabeludo Sensor de EEG

For scalp EEG research environments with laboratory mice, we designed a dry-type 16 channel EEG sensor which is non-invasive, deformable, and re-usable ...

In Vivo Methods to Assess Retinal Ganglion Cell and Optic Nerve Function and Structure in Large Animals

The optic nerve collects axons signals from the retinal ganglion cells and transmits visual signal to the brain. Large animal models of optic nerve injury are essential for translating novel therapeutic strategies from rodent models to clinical application due to their closer similarities to humans in size and anatomy. Here we describe some in vivo methods to evaluate the function and structure of the retinal ganglion cells (RGCs) and optic nerve (ON) in large animals, including visual evoked potential (VEP), pattern electroretinogram (PERG) and optical coherence tomography (OCT). Both goat and non-human primate were employed in this study. By presenting these in vivo methods step by step, we hope to increase experimental reproducibility among different labs and facilitate the usage of large animal models of optic neuropathies.

In Vivo Methods to Assess Retinal Ganglion Cell and Optic Nerve Function and Structure in Large Animals

Here we demostrate several in vivo tests (flash visual evoked potential, pattern electroretinogram and optic coherence tomography) in goat and rhesus macaque to understand the structure and function of the optic nerve and its neurons.

In vivo Métodos para avaliar a função e estrutura do gânglio de gânglios da retina e da estrutura em animais grandes

The optic nerve collects axons signals from the retinal ganglion cells and transmits visual signal to the brain. Large animal models of optic nerve injury ...

Inducing Local Demyelination in the Optic Nerve Using Lysolecithin

Source: You, Y. et al., <a href="https://appjove.unicartagenaproxy.elogim.com/v/52934">Visual Evoked Potential Recording in a Rat Model of Experimental Optic Nerve Demyelination.</a> J. Vis. Exp. (2015)
This video demonstrates the procedure of surgically accessing the optic nerve in an anesthetized animal and precisely delivering lysolecithin to induce focal demyelination, creating neuropathological conditions for further study.

Induzindo desmielinização local no nervo óptico usando lisolecitina

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

JoVE Encyclopedia of Experiments

Neuropathology

Epilepsy and Seizure Disorders

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

Source: Nguyen, C. T. et al., <a href="https://appjove.unicartagenaproxy.elogim.com/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. ...

Neurophysiology

Electrophysiology Techniques

Electron Microscopic Analysis of Myelin Damage in a Rat Model of Optic Nerve Injury

Take fixed optic nerve sections from a control rat and a rat with optic nerve injury.
The control section exhibits axons with tightly packed myelin sheaths containing concentric plasma membrane layers. The injured section exhibits decompacted myelin with large gaps.
Incubate with an osmium-ferrocyanide complex that binds to lipids and enhances the myelin sheath&#39;s contrast.
Treat with thiocarbohydrazide to create additional binding sites for osmium.
Reapply osmium to further enhance lipid contrast.
Stain with heavy metals, which bind to macromolecules and enhance structural contrast.
Dehydrate using increasing alcohol concentrations and rinse with acetone for resin embedding.
Embed the tissue in resin, and coat the resin with gold to improve image quality.
Use serial block-face scanning electron microscopy to simultaneously slice and image. Focus the electron beam on the surface and detect the backscattered electrons to generate images.
Myelin sheaths appear dark, while spaces within damaged sheaths appear lighter, allowing differentiation between normal and damaged myelin.

Análise Microscópica Eletrônica de Dano de Mielina em um Modelo de Rato de Lesão do Nervo Óptico

Neuromuscular Disorders

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

Source: You, Y., et al. <a href="https://appjove.unicartagenaproxy.elogim.com/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 ...