Este trabalho foi financiado pela Prova Descoberta UC da concessão Conceito e pelo NIH (R00 EB007241). Os autores também gostariam de agradecer a Jacqueline Hubbard por sua assistência neste experimento.

1. Preparação cirúrgico <ol><li> CD 1 fêmea ratos com idades entre 6-8 semanas foram utilizados nas nossas experiências. </li><li> Anestesiar o rato com uma injecção intraperitoneal de uma combinação de cetamina e xilazina (80 mg / kg ketamine/10 mg / kg de xilazina). Posicione o mouse sobre uma almofada de homeotérmicos para garantir a temperatura corporal ideal em ~ 37 ° C. Monitorar continuamente o nível de anestesia, testando os reflexos do animal (por exemplo, apertando o pé com uma pinça sem corte) e injetar mais anestesia quando necessário. </li><li> Lubrifique os dois olhos com uma pomada de lágrima artificial. Remova os cabelos no couro cabeludo utilizando uma lâmina de barbear e depilar residual utilizando almofadas de preparação de 70% de álcool. Aplique uma fina camada de Nair creme de depilação sobre o couro cabeludo e esperar 2 min para que ela tenha efeito. Limpe cuidadosamente afastado cabelo Nair e restantes utilizando solução salina umedecido cotonetes e almofadas de preparação de álcool. Couro cabeludo deve agora ser completamente sem pêlos. </li><li> Desinfetar couro cabeludo usando um betadine vara cotonete e limpe com 7Almofadas prep 0% de etanol. </li><li> Cuidadosamente enrole o animal em campos cirúrgicos para garantir a temperatura corporal ideal de ~ 37 ° C e montar o animal sobre uma armação estereotáxica para imobilizar o crânio. Bata levemente o crânio para garantir a sua estabilidade. A lista de materiais utilizados são fornecidas na Tabela 1. </li></ol> 2. Diluído crânio-Preparação Janela Cortical <ol><li> Iniciar a incisão na linha média, no ponto entre os olhos. Continuar caudalmente ao ponto da linha média entre as orelhas. Parte da pele com fórceps. </li><li> Localizar a área a ser diluído sob um microscópio de dissecação e retire cuidadosamente a fáscia usando uma pinça. Seque o crânio com cotonetes estéreis antes de criar a janela diluído cortical. Em nossos experimentos, nós criamos um 4 × 4 mm diluído janela craniana ~ 1 mm posterior e lateral para bregma. </li><li> Comece diluindo o crânio com uma rodada carbide com tamanho de broca 0,75 milímetros em uma broca cirúrgica com onl leve movimento radicaly. Não aplique pressão directa sobre o crânio. Pare de perfuração cada seg 20-30 para remover o pó de osso utilizando solução salina estéril e cotonetes e para evitar o superaquecimento do crânio. A solução salina irá também ajudar na dissipação do calor em todo o crânio. </li><li> Uma vez que a camada externa do osso compacto é completamente removido a camada de osso esponjoso do meio deve ser agora visíveis. Pode haver algum sangramento leve como vasos sanguíneos são mais evidentes na camada de osso esponjoso. Mudar para uma broca de pedra verde e continuar a perfuração utilizando cuidado extra como a camada esponjosa é mais delicada. A broca de pedra verde irá remover o material menos osso ao criar uniformidade em toda a janela craniano. Pare a perfuração de vez em quando para remover o pó de osso e para arrefecer o crânio. </li><li> Finalmente, quando o crânio tornou-se mais transparente e vasculatura do cérebro é agora visível, iniciar o polimento do crânio utilizando uma broca de polimento. Isso permitirá uma mais precisa desbaste enquanto alisando o crânio. Verifique magreza do skull batendo nele com uma pinça. Parar de polimento quando o crânio fica ligeiramente flexível. </li><li> A janela craniana diluído deve agora ser completamente liso e reflector e prontos para imagiologia (Figura 1). Devido à natureza dos tecidos altamente espalhamento do cérebro, do crânio deve ser diluído até, pelo menos, 55 mm para a penetração de profundidade óptima. A lista de materiais utilizados são fornecidas na Tabela 1. </li></ol> 3. Tomografia de coerência óptica <ol><li> Após a cirurgia está completa, verificar a taxa de animal respiração e reflexos para assegurar um nível adequado de anestesia e administrar anestesia adicional se necessário. Remover animal da armação estereotáxica, manter animais envolvido em panos cirúrgicos, e animais de transporte para a estação de imagiologia. </li><li> Antes de imagem para verificar os sinais reflexos e aplicar lágrima artificial adicional se necessário. Montar animal sobre a armação estereotáxica para fixar o crânio. </li><li> Coloque o animal sobOutubro câmara ea posição do TSCW sob o feixe óptico (Figura 2). Uma vista em corte transversal do crânio e no cérebro podem agora ser visualizada (Figura 3). </li><li> A aquisição de dados pode começar uma vez que área de interesse está localizada. Para os fins de imagem, usamos espelhos Galvo para alcançar uma janela de imagem com uma largura de 4,0 mm. Uma profundidade de 2 mm de imagem foi obtida com 6 mW de potência incidente e um ponto focal 1 mm abaixo do crânio diluído. Cada área transversal consistindo de 2.048 scans axiais com uma taxa de aquisição de 0,14 segundos por imagem. </li><li> Digitalizações volumétricas do cérebro pode também ser obtido por recolha de uma série de 2D imagens transversais usando dois conjuntos de espelhos para Galvo xy digitalização com o espelho de digitalização Galvo primeiro feixe na direcção sagital e o espelho Galvo segunda análise no coronal direção. </li></ol>

<ol>
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Imagens com outubro e um diluído crânio-se de uma técnica neuro-imaging romance que só recentemente foram investigadas 15, 16. Em nossos experimentos, demonstramos a viabilidade do SD-outubro de imagem através de um TSCW em um modelo de rato in vivo. A partir dos resultados, o crânio é diluído para cerca de 55 ^ m e a profundidade de penetração é obtida em cerca de 1 mm, com resolução de imagem de 8 um e 20 um na direcção axial e lateral, respectivamente. No perfil de intensidade do si...

Desde a sua introdução no início dos anos 1990, OCT tem sido amplamente utilizado para a imagiologia biológica da estrutura e função do tecido 2. Outubro gera imagens transversais através da medição de atraso de eco de tempo de 4 a luz retrodifundida pela implementação fonte de luz baixa coerência com um interferómetro de Michelson fibra óptica 2,4. SD-outubro, também conhecido como domínio de Fourier outubro (FD-OCT), foi introduzido pela primeira vez em 1995 5 e oferece uma modalidade de imagem superior em comparação com o tradicional domínio do tempo outubro (TD-OCT). Em SD-OCT, o braço de referência é mantido estacionário, resultando em uma alta velocidade e de aquisição de imagem ultra-alta resolução 6-9. Presentemente, os modelos TSCW têm sido largamente utilizados para aplicações em imagiologia do cérebro in vivo de dois fotões microscopia no lugar de uma craniotomia tradicional. Estes TSCW foram usados ​​simultaneamente com uma placa de crânio personalizado ou uma lamínula de vidro 10-13 para fornecer ima adicionalging estabilidade. Nos nossos estudos, observou-se que os acessórios tais como estes não são necessários para outubro de imagem quando um TSCW é usado. Portanto, a ausência de uma placa de crânio ou lamelas de vidro permite uma gama mais ampla de tamanho de janela de imagem uma vez que podem interferir com o feixe óptico e alterar imagens outubro A preparação diluída crânio tem provado ser vantajoso em estudos de imagem do cérebro utilizando dois fotões microscopia 10-13. Em nossos experimentos, nós utilizamos um sistema SD-OCT para a imagem do córtex in vivo através de um TSCW. Nosso costume SD-outubro de configuração de imagem contém uma banda larga, fonte de luz de baixa coerência consiste em dois diodos superluminescent (SLD) centradas em 1295 nm com uma largura de banda de 97 nm, resultando em uma resolução axial e lateral de 8 m e 20 um, respectivamente 14 . Com o nosso dispositivo de imagem óptica, prevemos que a imagem através de um TSCW tem um grande potencial na identificação e visualização de estruturas e funções no ctecido cerebral ptically denso.

<table border="1"><tbody><tr><td> Materiais </td><td> Companhia </td><td> Número de catálogo </td><td> Comentários </td></tr><tr><td> Cetamina </td><td> Phoenix Pharmaceuticals </td><td> 57319-542-02 </td><td></td></tr><tr><td> Xilazina </td><td> Akorn, Inc. </td><td> 139-236 </td><td></td></tr><tr><td> Pomada Lágrimas artificiais </td><td> Rugby </td><td> 0536-6550-91 </td><td></td></tr><tr><td> Nair </td><td> Church &amp; Dwight Co., Inc. </td><td> 4010130 </td><td></td></tr><tr><td> Estéril Álcool Prep Pad </td><td> Kendall Healthcare </td><td> 6818 </td><td></td></tr><tr><td> Algodão aplicadores com ponta </td><td> Fisherbrand </td><td> 23-400-115 </td><td></td></tr><tr><td> Vareta com tampão da solução Betadine </td><td> Purdue Produtos &lt;/ Td&gt; <td> 67618-153-01 </td><td></td></tr><tr><td> Solução Salina 0,9% </td><td> Phoenix Pharmaceuticals </td><td> 57319-555-08 </td><td></td></tr><tr><td> Quadro estereotáxico </td><td> Stoelting </td><td></td><td></td></tr><tr><td> Alta velocidade da broca cirúrgica das mãos </td><td> Foredom </td><td></td><td> 38.000 rpm </td></tr><tr><td> Carbide Rodada Bur </td><td> Stoelting </td><td></td><td> 0,75 milímetros </td></tr><tr><td> Dura-Green Pedras </td><td> Shofu </td><td></td><td> Shank: HP Shape: BA1 </td></tr><tr><td> Compomaster Grossa e Compomaster Polisher </td><td> Shofu </td><td></td><td> Forma: Mini-Pt. </td></tr><tr><td> SpaceDrapes </td><td> Braintree Scientific, Inc. </td><td></td><td></td></tr></tbody></table>

thinned-skull cortical window technique for in vivo optical coherence tomography imaging

Tomografia de coerência óptica (OCT) é uma técnica de imagem biomédica com resolução espacial-temporal. Com a sua abordagem minimamente invasiva outubro tem sido amplamente utilizado em oftalmologia, dermatologia, gastroenterologia e 1-3. Usando uma janela diluído crânio-cortical (TSCW), empregamos espectral-domínio outubro modalidade (SD-OCT) como uma ferramenta para a imagem do córtex in vivo. Comumente, uma abertura de caveira foi usada para neuroimagem, pois proporciona uma maior versatilidade, no entanto, uma abordagem TSCW é menos invasivo e é um meio eficaz para imagiologia de longa duração em estudos neuropatologia. Aqui, apresentamos um método de criação de um TSCW em um modelo de camundongo in vivo para outubro de imagem do córtex cerebral.

Após a criação de uma janela diluído sobre o córtex cerebral a vasculatura agora deve ser visualmente mais proeminente (Figura 1) e vai permitir uma maior profundidade de imagens (até 1 mm). O córtex direito é diluído para cerca de 55 pM quando comparado com um crânio normal, medido a 140 ^ m (Figura 1) e proporciona uma maior clareza óptica. Além disso o desbaste de 10-15 uM é possível 11 não, contudo, necessário que a utilização de folhas de vidro de cober...

Watch this Scientific Journal Video about Thinned-skull Cortical Window Technique for In Vivo Optical Coherence Tomography Imaging at JoVE.com

Thinned-skull Cortical Window Technique for In Vivo Optical Coherence Tomography Imaging

Apresenta-se um método de criação de uma janela diluído crânio-cortical (TSCW) em um modelo de rato para<em&gt; In vivo</em&gt; Outubro de imagem do córtex cerebral.

Diluído crânio-técnica de janela cortical para<em&gt; Em Vivo</em&gt; Tomografia de coerência óptica

Optical coherence tomography (OCT) is a biomedical imaging technique  with high spatial-temporal resolution. With its minimally invasive approach OCT  has ...

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Neuroscience

Thinned-skull Cortical Window Technique for In Vivo Optical Coherence Tomography Imaging

15.1K visualizações.  University of California, Riverside. Apresenta-se um método de criação de uma janela diluído crânio-cortical (TSCW) em um modelo de rato para In vivo Outubro de imagem do córtex cerebral.

Vídeo: Thinned-skull Cortical Window Technique for In Vivo Optical Coherence Tomography Imaging

A Thin-skull Window Technique for Chronic Two-photon In vivo Imaging of Murine Microglia in Models of Neuroinflammation

Traditionally in neuroscience, in vivo two photon imaging of the murine central nervous system has either involved the use of open-skull1,2 or thinned-skull 3 preparations. While the open-skull technique is very versatile, it is not optimal for studying microglia because it is invasive and can cause microglial activation. Even though the thinned-skull approach is minimally invasive, the repeated re-thinning of skull required for chronic imaging increases the risks of tissue injury and microglial activation and allows for a limited number of imaging sessions. Here we present a chronic thin-skull window method for monitoring murine microglia in vivo over an extended period of time using two-photon microscopy. We demonstrate how to prepare a stable, accessible, thinned-skull cortical window (TSCW) with an apposed glass coverslip that remains translucent over the course of three weeks of intermittent observation. This TSCW preparation is far more immunologically inert with respect to microglial activation than open craniotomy or repeated skull thinning and allows an arbitrary number of imaging sessions during a time period of weeks. We prepare TSCW in CX3CR1 GFP/+ mice 4 to visualize microglia with enhanced green fluorescent protein to &le;150 &mu;m beneath the pial surface. We also show that this preparation can be used in conjunction with stereotactic brain injections of the HIV-1 neurotoxic protein Tat, adjacent to the TSCW, which is capable of inducing durable microgliosis. Therefore, this method is extremely useful for examining changes in microglial morphology and motility over time in the living brain in models of HIV Associated Neurocognitive Disorder (HAND) and other neurodegenerative diseases with a neuroinflammatory component.

A Thin-skull Window Technique for Chronic Two-photon In vivo Imaging of Murine Microglia in Models of Neuroinflammation

We describe a method for repeatedly visualizing murine microglia and circulating monocytes in vivo over hours, days or weeks using transcranial two-photon microscopy. We demonstrate how to prepare a thinned-skull window that allows intermittent observation of quiescent microglia that can be activated by adjacent stereotactic injection of the HIV-1 regulatory protein Tat.

A Técnica de Janela crânio-fino para Crônica de dois fótons In vivo Imaging da Microglia murino em Modelos de Neuroinflammation

Traditionally in neuroscience, in vivo two photon imaging of the murine central nervous system has either involved the use of open-skull1,2 or ...

Neurociência

Chronic Imaging of Mouse Visual Cortex Using a Thinned-skull Preparation

In vivo imaging using two-photon laser scanning microscopy (2PLSM) allows the study of living cells and neuronal processes in the intact brain. The technique presented here allows the imaging of the same area of the brain at several time points (chronic imaging) with microscopic resolution allowing the tracking of dendritic spines which are the small structures that represent the majority of postsynaptic excitatory sites in the CNS. The ability to clearly resolve fine cortical structures over several time points has many advantages, specifically in the study of brain plasticity in which morphological changes at synapses and circuit remodeling may help explain underlying mechanisms. In this video and supplementary material, we show a protocol for chronic in vivo imaging of the intact brain using a thinned-skull preparation. The thinned-skull preparation is a minimally invasive approach, which avoids potential damage to the dura and/or cortex, thus reducing the onset of an inflammatory response. When this protocol is performed correctly, it is possible to clearly monitor changes in dendritic spine characteristics in the intact brain over a prolonged period of time.

In this video and supplemental material, we show a protocol for chronic in vivo imaging of the intact brain using a thinned-skull preparation.

Imagem crônica de rato Visual Cortex usando uma preparação diluída crânio-

In vivo imaging using two-photon laser scanning microscopy (2PLSM) allows the study of living cells and neuronal processes in the intact brain. The ...

A Polished and Reinforced Thinned-skull Window for Long-term Imaging of the Mouse Brain

In vivo imaging of cortical function requires optical access to the brain without disruption of the intracranial environment. We present a method to form a polished and reinforced thinned skull (PoRTS) window in the mouse skull that spans several millimeters in diameter and is stable for months. The skull is thinned to 10 to 15 &mu;m in thickness with a hand held drill to achieve optical clarity, and is then overlaid with cyanoacrylate glue and a cover glass to: 1) provide rigidity, 2) inhibit bone regrowth and 3) reduce light scattering from irregularities on the bone surface. Since the skull is not breached, any inflammation that could affect the process being studied is greatly reduced. Imaging depths of up to 250 &mu;m below the cortical surface can be achieved using two-photon laser scanning microscopy. This window is well suited to study cerebral blood flow and cellular function in both anesthetized and awake preparations. It further offers the opportunity to manipulate cell activity using optogenetics or to disrupt blood flow in targeted vessels by irradiation of circulating photosensitizers.

We present a method to form an imaging window in the mouse skull that spans millimeters and is stable for months without inflammation of the brain. This method is well suited for longitudinal studies of blood flow, cellular dynamics, and cell/vascular structure using two-photon microscopy.

A polido e reforçado Janela afinado crânio para longo prazo de imagens do cérebro de camundongo

In vivo imaging of cortical function requires optical access to the brain without disruption of the intracranial environment. We present a method to form ...

In Vivo Two-photon Imaging Of Experience-dependent Molecular Changes In Cortical Neurons

The brain's ability to change in response to experience is essential for healthy brain function, and abnormalities in this process contribute to a variety of brain disorders1,2. To better understand the mechanisms by which brain circuits react to an animal's experience requires the ability to monitor the experience-dependent molecular changes in a given set of neurons, over a prolonged period of time, in the live animal. While experience and associated neural activity is known to trigger gene expression changes in neurons1,2, most of the methods to detect such changes do not allow repeated observation of the same neurons over multiple days or do not have sufficient resolution to observe individual neurons3,4. Here, we describe a method that combines in vivo two-photon microscopy with a genetically encoded fluorescent reporter to track experience-dependent gene expression changes in individual cortical neurons over the course of day-to-day experience. 
One of the well-established experience-dependent genes is Activity-regulated cytoskeletal associated protein (Arc)5,6. The transcription of Arc is rapidly and highly induced by intensified neuronal activity3, and its protein product regulates the endocytosis of glutamate receptors and long-term synaptic plasticity7. The expression of Arc has been widely used as a molecular marker to map neuronal circuits involved in specific behaviors3. In most of those studies, Arc expression was detected by in situ hybridization or immunohistochemistry in fixed brain sections. Although those methods revealed that the expression of Arc was localized to a subset of excitatory neurons after behavioral experience, how the cellular patterns of Arc expression might change with multiple episodes of repeated or distinctive experiences over days was not investigated. 
In vivo two-photon microscopy offers a powerful way to examine experience-dependent cellular changes in the living brain8,9. To enable the examination of Arc expression in live neurons by two-photon microscopy, we previously generated a knock-in mouse line in which a GFP reporter is placed under the control of the endogenous Arc promoter10. This protocol describes the surgical preparations and imaging procedures for tracking experience-dependent Arc-GFP expression patterns in neuronal ensembles in the live animal. In this method, chronic cranial windows were first implanted in Arc-GFP mice over the cortical regions of interest. Those animals were then repeatedly imaged by two-photon microscopy after desired behavioral paradigms over the course of several days. This method may be generally applicable to animals carrying other fluorescent reporters of experience-dependent molecular changes4.

In Vivo Two-photon Imaging Of Experience-dependent Molecular Changes In Cortical Neurons

Experience-dependent molecular changes in neurons are essential for the brain's ability to adapt in response to behavioral challenges. An in vivo two-photon imaging method is described here that allows the tracking of such molecular changes in individual cortical neurons through genetically encoded reporters.

Vivo em dois fótons de imagem de experiência dependentes de alterações moleculares em neurônios corticais

The brain's ability to change in response to experience is essential for healthy brain function, and abnormalities in this process contribute to a variety ...

Two-Photon in vivo Imaging of Dendritic Spines in the Mouse Cortex Using a Thinned-skull Preparation

In the mammalian cortex, neurons form extremely complicated networks and exchange information at synapses. Changes in synaptic strength, as well as addition/removal of synapses, occur in an experience-dependent manner, providing the structural foundation of neuronal plasticity. As postsynaptic components of the most excitatory synapses in the cortex, dendritic spines are considered to be a good proxy of synapses. Taking advantages of mouse genetics and fluorescent labeling techniques, individual neurons and their synaptic structures can be labeled in the intact brain. Here we introduce a transcranial imaging protocol using two-photon laser scanning microscopy to follow fluorescently labeled postsynaptic dendritic spines over time in vivo. This protocol utilizes a thinned-skull preparation, which keeps the skull intact and avoids inflammatory effects caused by exposure of the meninges and the cortex. Therefore, images can be acquired immediately after surgery is performed. The experimental procedure can be performed repetitively over various time intervals ranging from hours to years. The application of this preparation can also be expanded to investigate different cortical regions and layers, as well as other cell types, under physiological and pathological conditions.

Two-Photon in vivo Imaging of Dendritic Spines in the Mouse Cortex Using a Thinned-skull Preparation

Time-lapse imaging in the living animal provides valuable information on structural reorganization in the intact brain. Here, we introduce a thinned-skull preparation that allows transcranial imaging of fluorescently labeled synaptic structures in the living mouse cortex by two-photon microscopy.

Two-Photon<em&gt; In vivo</em&gt; Imagem de espinhas dendríticas no Rato Cortex Usando um desbaste-crânio Preparação

In the mammalian cortex, neurons form extremely complicated networks and exchange information at synapses. Changes in synaptic strength, as well as ...

Optical Coherence Tomography: Imaging Mouse Retinal Ganglion Cells In Vivo

Structural changes in the retina are common manifestations of ophthalmic diseases. Optical coherence tomography (OCT) enables their identification in vivo&#8212;rapidly, repetitively, and at a high resolution. This protocol describes OCT imaging in the mouse retina as a powerful tool to study optic neuropathies (OPN). The OCT system is an interferometry-based, non-invasive alternative to common post mortem histological assays. It provides a fast and accurate assessment of retinal thickness, allowing the possibility to track changes, such as retinal thinning or thickening. We present the imaging process and analysis with the example of the Opa1delTTAG mouse line. Three types of scans are proposed, with two quantification methods: standard and homemade calipers. The latter is best for use on the peripapillary retina during radial scans; being more precise, is preferable for analyzing thinner structures. All approaches described here are designed for retinal ganglion cells (RGC) but are easily adaptable to other cell populations. In conclusion, OCT is efficient in mouse model phenotyping and has the potential to be used for the reliable evaluation of therapeutic interventions.

Optical Coherence Tomography: Imaging Mouse Retinal Ganglion Cells In Vivo

This manuscript describes a protocol for the in vivo imaging of the mouse retina with high-resolution spectral domain optical coherence tomography (SD-OCT). It focuses on retinal ganglion cells (RGC) in the peripapillary region, with several scanning and quantifying approaches described.

Tomografia de coerência óptica: Imagens Mouse ganglionares da retina células In Vivo

Structural changes in the retina are common manifestations of ophthalmic diseases. Optical coherence tomography (OCT) enables their identification in ...

In Vivo Two-photon Imaging of Cortical Neurons in Neonatal Mice

Two-photon imaging is a powerful tool for the in vivo analysis of neuronal circuits in the mammalian brain. However, a limited number of in vivo imaging methods exist for examining the brain tissue of live newborn mammals. Herein we summarize a protocol for imaging individual cortical neurons in living neonatal mice. This protocol includes the following two methodologies: (1) the Supernova system for sparse and bright labeling of cortical neurons in the developing brain, and (2) a surgical procedure for the fragile neonatal skull. This protocol allows the observation of temporal changes of individual cortical neurites during neonatal stages with a high signal-to-noise ratio. Labeled cell-specific gene silencing and knockout can also be achieved by combining the Supernova with RNA interference and CRISPR/Cas9 gene editing systems. This protocol can, thus, be used for analyzing the developmental dynamics of cortical neurons, molecular mechanisms that control the neuronal dynamics, and changes in neuronal dynamics in disease models.

In Vivo Two-photon Imaging of Cortical Neurons in Neonatal Mice

We present an in vivo two-photon imaging protocol for imaging the cerebral cortex of neonatal mice. This method is suitable for analyzing the developmental dynamics of cortical neurons, the molecular mechanisms that control the neuronal dynamics, and the changes in neuronal dynamics in disease models.

Na Vivo Imagem de dois fotões de neurônios Cortical em camundongos Neonatais

Two-photon imaging is a powerful tool for the in vivo analysis of neuronal circuits in the mammalian brain. However, a limited number of in vivo imaging ...

Using Optical Coherence Tomography and Optokinetic Response As Structural and Functional Visual System Readouts in Mice and Rats

Optical coherence tomography (OCT) is a fast, non-invasive, interferometric technique allowing high-resolution retinal imaging. It is an ideal tool for the investigation of processes of neurodegeneration, neuroprotection and neuro-repair involving the visual system, as these often correlate well with retinal changes. As a functional readout, visually evoked compensatory eye and head movements are commonly used in experimental models involving the visual function. Combining both techniques allows a quantitative in vivo investigation of structure and function, which can be used to investigate the pathological conditions or to evaluate the potential of novel therapeutics. A great benefit of the presented techniques is the possibility to perform longitudinal analyses allowing the investigation of dynamic processes, reducing variability and cuts down the number of animals needed for the experiments. The protocol described aims to provide a manual for acquisition and analysis of high quality retinal scans of mice and rats using a low cost customized holder with an option to deliver inhalational anesthesia. Additionally, the proposed guide is intended as an instructional manual for researchers using optokinetic response (OKR) analysis in rodents, which can be adapted to their specific needs and interests.

A detailed protocol for the assessment of structural and visual readouts in rodents by optical coherence tomography and optokinetic response is presented. The results provide valuable insights for ophthalmologic as well as neurologic research.

Usando a tomografia de coerência óptica e resposta Optokinetic como estrutural e funcional sistema Visual leituras em camundongos e ratos

Optical coherence tomography (OCT) is a fast, non-invasive, interferometric technique allowing high-resolution retinal imaging. It is an ideal tool for ...

In Vivo Optical Calcium Imaging of Learning-Induced Synaptic Plasticity in Drosophila melanogaster

Decades of research in many model organisms have led to the current concept of synaptic plasticity underlying learning and memory formation. Learning-induced changes in synaptic transmission are often distributed across many neurons and levels of processing in the brain. Therefore, methods to visualize learning-dependent synaptic plasticity across neurons are needed. The fruit fly Drosophila melanogaster represents a particularly favorable model organism to study neuronal circuits underlying learning. The protocol presented here demonstrates a way in which the processes underlying the formation of associative olfactory memories, i.e., synaptic activity and their changes, can be monitored in vivo. Using the broad array of genetic tools available in Drosophila, it is possible to specifically express genetically encoded calcium indicators in determined cell populations and even single cells. By fixing a fly in place, and opening the head capsule, it is possible to visualize calcium dynamics in these cells whilst delivering olfactory stimuli. Additionally, we demonstrate a set-up in which the fly can be subjected, simultaneously, to electric shocks to the body. This provides a system in which flies can undergo classical olfactory conditioning - whereby a previously na&#239;ve odor is learned to be associated with electric shock punishment - at the same time as the representation of this odor (and other untrained odors) is observed in the brain via two-photon microscopy. Our lab has previously reported the generation of synaptically localized calcium sensors, which enables one to confine the fluorescent calcium signals to pre- or postsynaptic compartments. Two-photon microscopy provides a way to spatially resolve fine structures. We exemplify this by focusing on neurons integrating information from the mushroom body, a higher-order center of the insect brain. Overall, this protocol provides a method to examine the synaptic connections between neurons whose activity is modulated as a result of olfactory learning.

In Vivo Optical Calcium Imaging of Learning-Induced Synaptic Plasticity in Drosophila melanogaster

Here we present a protocol with which pre- and/or postsynaptic calcium can be visualized in the context of Drosophila learning and memory. In vivo calcium imaging using synaptically localized calcium sensors is combined with a classical olfactory conditioning paradigm such that the synaptic plasticity underlying this type of associative learning may be determined.

In vivo Optical cálcio Imaging de aprendizagem induzida por plasticidade sináptica em Drosophila melanogaster

Decades of research in many model organisms have led to the current concept of synaptic plasticity underlying learning and memory formation. ...

Retinal Vascular Reactivity as Assessed by Optical Coherence Tomography Angiography

The vascular supply to the retina has been shown to dynamically adapt through vasoconstriction and vasodilation to accommodate the metabolic demands of the retina. This process, referred to as retinal vascular reactivity (RVR), is mediated by neurovascular coupling, which is impaired very early in retinal vascular diseases such as diabetic retinopathy. Therefore, a clinically feasible method of assessing vascular function may be of significant interest in both research and clinical settings. Recently, in vivo imaging of the retinal vasculature at the capillary level has been made possible by the FDA approval of optical coherence tomography angiography (OCTA), a noninvasive, minimal risk and dyeless angiography method with capillary level resolution. Concurrently, physiological and pathological changes in RVR have been shown by several investigators. The method shown in this manuscript is designed to investigate RVR using OCTA with no need for alterations to the clinical imaging procedures or device. It demonstrates real time imaging of the retina and retinal vasculature during exposure to hypercapnic or hyperoxic conditions. The exam is easily performed with two personnel in under 30 min with minimal subject discomfort or risk. This method is adaptable to other ophthalmic imaging devices and the applications may vary based on the composition of the gas mixture and patient population. A strength of this method is that it allows for an investigation of retinal vascular function at the capillary level in human subjects in vivo. Limitations of this method are largely those of OCTA and other retinal imaging methods including imaging artifacts and a restricted dynamic range. The results obtained from the method are OCT and OCTA images of the retina. These images are amenable to any analysis that is possible on commercially available OCT or OCTA devices. The general method, however, can be adapted to any form of ophthalmic imaging.

This article describes a method for measuring retinal vasculature reactivity in vivo with human subjects using a gas breathing provocation technique to deliver vasoactive stimuli while acquiring retinal images.

Reatividade Vascular da Retina avaliada pela Angiografia de Tomografia de Coerência Óptica

The vascular supply to the retina has been shown to dynamically adapt through vasoconstriction and vasodilation to accommodate the metabolic demands of ...

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