Este trabajo fue apoyado por la prueba de UC Discovery subvención Concepto y por el NIH (R00 EB007241). Los autores también desean agradecer a Jacqueline Hubbard por su ayuda en este experimento.

1. Preparación quirúrgica <ol><li> Ratones hembra CD 1 entre las edades de 6-8 semanas se usaron en nuestros experimentos. </li><li> Se anestesia el ratón con una inyección intraperitoneal de una combinación de ketamina y xilazina (80 mg / kg ketamine/10 mg / kg de xilazina). Coloque el ratón sobre una almohadilla homeotérmico para garantizar una temperatura corporal óptima a ~ 37 ° C. Supervisar continuamente el nivel de anestesia por probar reflejos animal (por ejemplo, pellizcar pie con fórceps romos) e inyectar más anestesia cuando sea necesario. </li><li> Lubricar ambos ojos con un ungüento de lágrima artificial. Elimine los pelos en el cuero cabelludo con una navaja de afeitar y depilar residual usando 70% almohadillas con alcohol. Aplique una capa delgada de crema de depilación Nair sobre el cuero cabelludo y esperar 2 minutos para que haga efecto. Limpie suavemente el pelo Nair y restantes humedecido con solución salina hisopos de algodón y almohadillas de preparación con alcohol. Scalp ahora debe estar completamente sin pelo. </li><li> Desinfecte cuero cabelludo con un palo betadine hisopo y limpiar con 70% de etanol almohadillas de preparación. </li><li> Envuelva cuidadosamente el animal en paños quirúrgicos para garantizar una temperatura óptima del cuerpo de ~ 37 ° C y montar el animal en un marco estereotáxico para inmovilizar el cráneo. Golpee suavemente el cráneo para asegurar su estabilidad. Una lista de los materiales utilizados se proporcionan en la Tabla 1. </li></ol> 2. Diluido-skull Preparación ventana cortical <ol><li> Inicie la incisión en el punto de la línea media entre los ojos. Continuar caudalmente hasta el punto de la línea media entre las orejas. Parte de la piel con pinzas. </li><li> Localizar el área a ser diluido con un microscopio de disección y se retire suavemente la fascia usando unas pinzas. Seque el cráneo con hisopos de algodón estériles antes de crear la ventana cortical adelgazada. En nuestros experimentos, hemos creado un 4 × 4 mm adelgazada ventana craneal ~ 1 mm posterior y lateral al bregma. </li><li> Comience el adelgazamiento de la calavera con una fresa redonda de carburo con el tamaño de la broca de 0,75 mm en un taladro quirúrgico utilizando sólo su luz movimiento de barridoy. No aplique presión directa en el cráneo. Deje de perforar cada segundo 20-30 para eliminar el polvo de hueso con solución salina estéril y torundas de algodón y evitar el sobrecalentamiento del cráneo. La solución salina también ayuda a disipar el calor por todo el cráneo. </li><li> Una vez que la capa exterior del hueso compacto se elimina por completo la capa media del hueso esponjoso debe ser visible. Puede haber un poco de sangrado como los vasos sanguíneos son más evidentes en la capa de hueso esponjoso. Cambie a una fresa de piedra verde y continuar perforando con mucho cuidado ya que la capa esponjosa es más delicado. La fresa de piedra verde se retire el material menos hueso al crear uniformidad en toda la ventana craneal. Detener la perforación de vez en cuando para quitar el polvo de hueso y para enfriar el cráneo. </li><li> Finalmente, cuando el cráneo se ha vuelto más transparente y la vasculatura del cerebro es ahora visible, empezar a pulir el cráneo con una fresa de pulido. Esto permitirá una más precisa adelgazamiento mientras alisar el cráneo. Compruebe delgadez de la skull golpeando suavemente sobre ella con fórceps. Deje de pulido cuando el cráneo se vuelve ligeramente flexible. </li><li> La ventana craneal adelgazado ahora debe ser completamente lisa y reflectante y listo para la formación de imágenes (Figura 1). Debido a la naturaleza de los tejidos altamente dispersión del cerebro, el cráneo debe ser diluido a por lo menos 55 micras de profundidad de penetración óptima. Una lista de los materiales utilizados se proporcionan en la Tabla 1. </li></ol> 3. Tomografía de Coherencia Óptica de imagen <ol><li> Después de la cirugía se ha completado, compruebe tasa de respiración de los animales y los reflejos para asegurar un nivel adecuado de anestesia y administrar anestesia adicional si es necesario. Eliminar el animal a la estructura estereotáxica, mantener los animales envuelto en paños quirúrgicos, y el transporte de animales a la estación de formación de imágenes. </li><li> Antes de imágenes para verificar si existen signos reflejos y aplicar lágrimas artificiales adicional si es necesario. Montar los animales en el marco estereotáxico para asegurar el cráneo. </li><li> Lugar animal bajoOctubre cámara y la posición de la TSCW bajo el haz óptico (Figura 2). Una vista en sección transversal del cráneo y el cerebro ahora se puede visualizar (Figura 3). </li><li> La adquisición de datos puede comenzar una vez área de interés se encuentra. Para los propósitos de formación de imágenes, se utiliza espejos galvo para conseguir una ventana de imagen con una anchura de 4,0 mm. Una profundidad de imagen de 2 mm se obtuvo con 6 mW de potencia incidente y un punto focal 1 mm por debajo del cráneo adelgazada. Cada área transversal consistió de 2.048 cortes axiales con una velocidad de adquisición de 0,14 seg por imagen. </li><li> Exploraciones volumétricas del cerebro también se puede obtener mediante la recopilación de una serie de 2D imágenes transversales mediante el uso de dos conjuntos de espejos galvo de barrido XY con la primera espejo galvo barrido del haz en la dirección sagital y el segundo espejo de escaneo galvo en el coronal dirección. </li></ol>

<ol>
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No hay conflictos de interés declarado.

Proyección de imagen con OCT y un cráneo adelgazado-es una novela de neuroimagen técnica que sólo se ha investigado recientemente 15, 16. En nuestros experimentos, hemos demostrado la viabilidad de la SD-OCT imágenes a través de un TSCW en un modelo de ratón in vivo. A partir de nuestros resultados, el cráneo se adelgaza a aproximadamente 55 micras y con la profundidad de penetración se obtiene en aproximadamente 1 mm con una resolución de imagen de 8 micras y 20 micras en la dirección axi...

Desde su introducción en la década de 1990, octubre se ha utilizado ampliamente para formación de imágenes biológicas de la estructura tisular y la función 2. Octubre genera imágenes transversales mediante la medición de retardo del eco de tiempo de 4 luz dispersada por la aplicación de fuente bajo la luz coherencia con un interferómetro de Michelson fibra óptica 2,4. SD-OCT, también conocido como dominio de Fourier OCT (OCT-DF), fue introducido por primera vez en 1995 5, y ofrece una modalidad de imagen superior en comparación con el tradicional dominio de tiempo OCT (OCT-DT). En SD-octubre, el brazo de referencia se mantiene estacionaria que resulta en una velocidad alta y ultra adquisición de imagen de alta resolución 6-9. Actualmente, los modelos TSCW se han utilizado en gran medida para aplicaciones in vivo de imágenes del cerebro de dos fotones microscopía en lugar de una craneotomía tradicional. Estos TSCW se han utilizado conjuntamente con una placa de cráneo personalizado o un cubreobjetos de vidrio 10-13 para proporcionar adicional imaging estabilidad. En nuestros estudios, hemos observado que los accesorios de este tipo no son necesarios para octubre de imagen cuando se utiliza un TSCW. Por lo tanto, la falta de una placa de cráneo o cubierta de vidrio se desliza permite una gama más amplia de tamaño de imagen de la ventana ya que pueden interferir con el haz óptico y modificar las imágenes octubre Una preparación adelgazada cráneo ha demostrado ser ventajosa en los estudios de imágenes del cerebro usando microscopía de dos fotones 10-13. En nuestros experimentos, utilizamos un sistema SD-OCT para la imagen de la corteza en vivo a través de un TSCW. Nuestra costumbre SD-OCT configuración de imagen contiene una banda ancha, de baja coherencia fuente de luz que consiste en dos diodos superluminiscente (SLD) con centro en 1295 nm con un ancho de banda de 97 nm que resulta en una resolución axial y lateral de 8 micras y 20 micras, respectivamente 14 . Con nuestro dispositivo de formación de imágenes ópticas, prevemos que las imágenes a través de un TSCW tiene un gran potencial en la identificación y la visualización de las estructuras y funciones en la juntacerebro ptically denso tejido.

<table border="1"><tbody><tr><td> Materiales </td><td> Empresa </td><td> Número de catálogo </td><td> Comentarios </td></tr><tr><td> La ketamina </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> Lágrimas artificiales Ungüento </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 Alcohol Prep Pad </td><td> Kendall Healthcare </td><td> 6818 </td><td></td></tr><tr><td> Aplicadores con punta de algodón </td><td> Fisherbrand </td><td> 23-400-115 </td><td></td></tr><tr><td> Betadine solución bastoncillo con hisopo </td><td> Purdue Productos &lt;/ Td&gt; <td> 67618-153-01 </td><td></td></tr><tr><td> Solución salina, 0,9% </td><td> Phoenix Pharmaceuticals </td><td> 57319-555-08 </td><td></td></tr><tr><td> Estereotáctica Frame </td><td> Stoelting </td><td></td><td></td></tr><tr><td> Alta velocidad Taladro quirúrgico </td><td> Foredom </td><td></td><td> 38.000 rpm </td></tr><tr><td> Carburo de fresa redonda </td><td> Stoelting </td><td></td><td> 0,75 mm </td></tr><tr><td> Dura-Green Stones </td><td> Shofu </td><td></td><td> Shank: HP Forma: BA1 </td></tr><tr><td> CompoMaster gruesa y pulidora CompoMaster </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

Tomografía de Coherencia Óptica (OCT) es una técnica de imagen biomédica con alta resolución espacial y temporal. Con su enfoque mínimamente invasivo octubre se ha utilizado ampliamente en oftalmología, dermatología, gastroenterología y 1-3. Usando una ventana adelgazado-skull cortical (TSCW), empleamos dominio espectral OCT (SD-OCT) modalidad como una herramienta para la imagen de la corteza en vivo. Comúnmente, un cráneo abierto-se ha utilizado para neuroimagen, ya que proporciona más versatilidad, sin embargo, un enfoque TSCW es menos invasiva y es un medio eficaz para la formación de imágenes a largo plazo en los estudios de neuropatología. Aquí, se presenta un método de creación de un TSCW en un modelo de ratón para la formación de imágenes in vivo octubre de la corteza cerebral.

Después de crear una ventana adelgazada sobre la corteza cerebral de la vasculatura ahora debería ser más visualmente prominente (Figura 1) y permitirá una profundidad de imagen más profundo (hasta 1 mm). La corteza derecha se adelgaza a aproximadamente 55 micras, en comparación con un cráneo normal medido a 140 micras (figura 1) y proporciona una mayor claridad óptica. Además adelgazamiento a 10-15 micras es posible 11 no obstante, es necesario que el uso de cubreob...

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

Se presenta un método de creación de una ventana adelgazada cráneo cortical (TSCW) en un modelo de ratón para<em&gt; In vivo</em&gt; Imágenes de OCT de la corteza cerebral.

Diluido-skull técnica de ventana cortical para<em&gt; En Vivo</em&gt; Tomografía de Coherencia Óptica de imagen

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

thinned-skull-cortical-window-technique-for-vivo-optical-coherence

Research

JoVE Journal

Neuroscience

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

15.1K vistas.  University of California, Riverside. Se presenta un método de creación de una ventana adelgazada cráneo cortical (TSCW) en un modelo de ratón para In vivo Imágenes de OCT de la corteza cerebral.

Video: 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.

Una delgada del cráneo ventana Técnica para la crónica de dos fotones En vivo Imágenes de la microglía murina en los modelos de la neuroinflamación

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

Investigación

Neurociencias

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.

Imagen crónica de la corteza visual del ratón usando una preparación de Diluido-cráneo

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.

Un pulido y reforzado Diluido cráneo-Ventana para a largo plazo de imágenes del cerebro de ratón

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.

In vivo de dos fotones de imágenes de dependientes Experience-Los cambios moleculares en las neuronas corticales

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.

De dos fotones<em&gt; In vivo</em&gt; Imágenes de las espinas dendríticas en la corteza del ratón Usando un Diluido-cráneo Preparación

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.

Tomografía de coherencia óptica: Proyección de imagen de ratón ganglionares de la retina las 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.

En Vivo Proyección de imagen de dos fotones de neuronas corticales en ratones neonatales

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.

Utilizando tomografía de coherencia óptica y respuesta Optokinetic como lecturas de sistema Visual estructural y funcional en ratones y ratas

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.

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.

Reactividad Vascular Retinal evaluada por Angiografía por Tomografía de Coherencia Óptica

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

Diluido-skull técnica de ventana cortical para

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