Name: implantation of a cranial window for repeated in vivo imaging in awake mice
Uploaded: 2021-06-22T15:00:00
Description: Watch this Scientific Journal Video about Implantation of a Cranial Window for Repeated In Vivo Imaging in Awake Mice at JoVE.com

All animal experiments were performed in accordance with guidelines approved by the IACUC at the University of Nebraska Medical Center.
1. Before surgery
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	<li>Prepare pipettes for viral injections. Pull borosilicate glass capillaries using a pipette puller and bevel the pipette at a 20&#176; angle. Sterilize the pipettes overnight.</li>
	<li>Prepare fresh pieces of sterile gel foam by cutting them into small squares. Submerge the gel foam in a sterile microfuge tube containing 0.5 mL of...

<ol>
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(88), e51869 (2014).</li><li>Holtmaat, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=high-resolution+imaging+in+the+mouse+neocortex+through+a+chronic+cranial+window.">high-resolution imaging in the mouse neocortex through a chronic cranial window.</a> Nature Protocols. 4 (8), 1128-1144 (2009).</li><li>Hauglund, N. 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Here, we have presented a protocol for the implantation of chronic cranial windows for in vivo imaging of cortical astrocytes and neurons in awake, head-restrained mice on an air-lifted home cage. Specific examples have been provided of the cranial window application for imaging astrocytes that express GECIs and neuronal synaptic structures. With the use of multiphoton microscopy, astrocytic calcium signaling dynamics and structural synaptic dynamics can be recorded repeatedly over days.
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The ability to perform in vivo multiphoton fluorescence microscopy in the cortex of mice is paramount to the study of cellular signaling and structure1,2,3,4,5,6,7,8,9, disease pathology10,11, and cellular development12,13. With the implantation of chronic cranial windows, longitudinal imaging is possible, allowing for repeated imaging of cortical areas for days, weeks, or months13,14 in live animals. Multiphoton microscopy is ideal for in vivo, repeated imaging because of improved depth probing and reduced photodamage associated with the infrared laser used. This allows for the study of molecular and cellular dynamics of specific cells in various cortical regions.
Multiphoton microscopy has been used for in vivo imaging of neuronal and glial cells in mice15,16,17,18,19,20. Various strategies can be implemented to label particular cell types and areas of interest. One common approach is to drive the expression of genetically encoded fluorescent proteins in a cell-specific manner using the Cre-Lox recombination system. This can be performed with genetically modified mice, e.g., crossing tdTomato &#34;floxed&#34; mouse (Ai14) with a mouse expressing Cre-recombinase under a promoter of interest21. Alternatively, cell- and site-specific labeling can be achieved with viral injections. Here, a virus encoding Cre recombinase under a cell-specific promotor and a virus encoding a floxed gene of interest are injected into a defined region. Appropriate cell types receiving both viral vectors will then express the desired gene(s). These genes can be structural markers, such as tdTomato, to view changes in cellular morphology22 or genetically encoded calcium indicators (GECIs), such as GCaMP and/or RCaMP, to examine calcium dynamics23. Methods of genetic recombination can be applied individually or in combination to label one or more cell types. A third approach, not requiring transgenic mice or viral constructs (which have limited packaging capacity), is in utero electroporation of DNA constructs24. Depending on the timing of the electroporation, different cell types can be targeted25,26,27.
When performing multiphoton imaging, mice can be imaged while awake or anesthetized. Imaging of awake mice can be performed by securing the mouse via an attached head plate28. This approach is made less stressful by allowing relatively free movement of the animal using methods, such as free-floating, air-supported Styrofoam balls29, free-floating treadmills1, or an air-lifted home cage system where mice are fastened by an attached head plate and allowed to move in an open chamber30. For each of these imaging conditions, it will first be necessary to habituate the mice to the imaging setup. This paper describes the habituation and imaging procedure using an air-lifted home cage system.
This protocol describes the implantation of a chronic cranial window for longitudinal in vivo imaging in the cortex. Here, we will use mice that conditionally express GCaMP6f in astrocytes to monitor calcium signaling dynamics. Further, this paper describes the procedure for viral injections using tdTomato as a label for neurons. This allows the determination of changes in neuronal synaptic structure and/or the availability as a structural marker that enables repeated imaging of the same astrocyte. Throughout the protocol, crucial steps will be highlighted to ensure the best possible quality of images obtained from multiphoton microscopy.

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			<td>Mylan Institutional, LLC.</td>
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			<td>Dissecting Microscope</td>
			<td>Nikon</td>
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			<td>Duralay Liquid&#160; (dental cement liquid)</td>
			<td>Patterson Dental</td>
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			<td>Eye Ointment</td>
			<td>Dechra</td>
			<td>17033-211-38</td>
			<td>Surgery Supply</td>
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		<tr>
			<td>Fiber Lite High Intensity Illuminator</td>
			<td>Dolan-Jenner Industries</td>
			<td></td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>Forceps (Large)</td>
			<td>World Precision Instruments</td>
			<td>14099</td>
			<td>Surgery Tools</td>
		</tr>
		<tr>
			<td>Forceps (Small)</td>
			<td>World Precision Instruments</td>
			<td>501764</td>
			<td>Surgery Tools</td>
		</tr>
		<tr>
			<td>GCaMP6f B6; 129S-Gt(ROSA)26Sortm95.1(CAGGCaMP6f)Hze/J</td>
			<td>The Jackson Laboratory</td>
			<td>Stock No: 024105</td>
			<td>Mouse line</td>
		</tr>
		<tr>
			<td>Germinator</td>
			<td>Fisher Scientific</td>
			<td></td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>GLAST-CreER Tg(Slc1a3-cre/ERT) 1Nat/J</td>
			<td>The Jackson Laboratory</td>
			<td>Stock No: 012586</td>
			<td>Mouse Line</td>
		</tr>
		<tr>
			<td>Headplate</td>
			<td>Neurotar</td>
			<td>Model 1, Model 3</td>
			<td>Surgery Supply</td>
		</tr>
		<tr>
			<td>Hemostatic forceps</td>
			<td>World Precision Instruments</td>
			<td>501705</td>
			<td>Surgery Tools</td>
		</tr>
		<tr>
			<td>Holder for 15o Pointed Blade</td>
			<td>World Precision Instruments</td>
			<td>501247</td>
			<td>Surgery Tools</td>
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		<tr>
			<td>Holder for Scalpel Blades</td>
			<td>World Precision Instruments</td>
			<td>500236</td>
			<td>Surgery Tools</td>
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		<tr>
			<td>Iodine Prep Pads</td>
			<td>Avantor</td>
			<td>15648-926</td>
			<td>Surgery Supply</td>
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		<tr>
			<td>Isoflurane</td>
			<td>Piramal</td>
			<td></td>
			<td>Surgery Supply</td>
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		<tr>
			<td>Isoflurane table top system with Induction Box</td>
			<td>Harvard Apparatus</td>
			<td></td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>Isoflurane Vaporizer</td>
			<td>SurgiVet</td>
			<td></td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>Krazy Glue</td>
			<td>Office Depot</td>
			<td>KG517</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Loctite 401</td>
			<td>Henkel</td>
			<td>40140</td>
			<td>fast-curing instant adhesive</td>
		</tr>
		<tr>
			<td>Loctite 454</td>
			<td>Fisher Scientific</td>
			<td>NC9194415</td>
			<td>cyanoacrylate adhesive gel</td>
		</tr>
		<tr>
			<td>Micropipette Puller</td>
			<td>Sutter Instruments</td>
			<td></td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>Multiphoton Microscope</td>
			<td></td>
			<td></td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>Nitrogen</td>
			<td>Matheson</td>
			<td>NI M200</td>
			<td>Gas</td>
		</tr>
		<tr>
			<td>Oxygen</td>
			<td>Matheson</td>
			<td>OX M250</td>
			<td>Gas</td>
		</tr>
		<tr>
			<td>Picospritzer</td>
			<td>Parker</td>
			<td></td>
			<td>intracellular microinjection dispense system</td>
		</tr>
		<tr>
			<td>Pipette Tips</td>
			<td>Rainin</td>
			<td>17014340</td>
			<td>Surgery Supply</td>
		</tr>
		<tr>
			<td>Rodent Hair Trimmer</td>
			<td>Wahl</td>
			<td></td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>Saline (0.9% Sodium Chloride)</td>
			<td>Med Vet International</td>
			<td>RX0.9NACL-30BAC</td>
			<td>Surgery Supply</td>
		</tr>
		<tr>
			<td>Scalpel Blades, Size 11</td>
			<td>Integra</td>
			<td>4-111</td>
			<td>Surgery Tools</td>
		</tr>
		<tr>
			<td>Scissors</td>
			<td>World Precision Instruments</td>
			<td>503667</td>
			<td>Surgery Tools</td>
		</tr>
		<tr>
			<td>Stereotaxic Instrument</td>
			<td>Stoelting</td>
			<td></td>
			<td>Equipment</td>
		</tr>
		<tr>
			<td>Sugi Sponge Strips (sponge strips)</td>
			<td>Kettenbach Dental</td>
			<td>31002</td>
			<td>Surgery Supply</td>
		</tr>
		<tr>
			<td>SURGIFOAM (gel foam)</td>
			<td>Ethicon</td>
			<td>1972</td>
			<td>Surgery Supply</td>
		</tr>
		<tr>
			<td>Syringe with 26 G Needle</td>
			<td>BD</td>
			<td>309625</td>
			<td>Surgery Supply</td>
		</tr>
		<tr>
			<td>Tamoxifen</td>
			<td>Sigma Aldrich</td>
			<td>T5648-1G</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Ti:Sapphire Laser</td>
			<td>Coherent</td>
			<td></td>
			<td>Equipment</td>
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		<tr>
			<td>Transfer Pipettes</td>
			<td>Fisher Scientific</td>
			<td>13-711-9AM</td>
			<td>Surgery Supply</td>
		</tr>
		<tr>
			<td>Water Blanket</td>
			<td>Fisher Scientific</td>
			<td></td>
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		</tr>
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			<td>Xylocaine MPF with Epinephrine (1:200,000), 10 mg/mL</td>
			<td>Fresenius Kabi USA</td>
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implantation of a cranial window for repeated in vivo imaging in awake mice

To fully understand the cellular physiology of neurons and glia in behaving animals, it is necessary to visualize their morphology and record their activity in vivo in behaving mice. This paper describes a method for the implantation of a chronic cranial window to allow for the longitudinal imaging of brain cells in awake, head-restrained mice. In combination with genetic strategies and viral injections, it is possible to label specific cells and regions of interest with structural or physiological markers. This protocol demonstrates how to combine viral injections to label neurons in the vicinity of GCaMP6-expressing astrocytes in the cortex for simultaneous imaging of both cells through a cranial window. Multiphoton imaging of the same cells can be performed for days, weeks, or months in awake, behaving animals. This approach provides researchers with a method for viewing cellular dynamics in real time and can be applied to answer a number of questions in neuroscience.

The quality of the cranial window can be assessed by how crisp the neuronal structures appear. In a good window, dendritic spines are clearly visible (Figure 1). With the structural and positional data stored, the same animal can be imaged repeatedly for days, weeks, or months to examine the same cells (Figure 1). The images in Figure 1 were obtained from the forelimb region of the primary motor cortex (in a 5 mm window). A variety ...

Watch this Scientific Journal Video about Implantation of a Cranial Window for Repeated In Vivo Imaging in Awake Mice at JoVE.com

Implantation of a Cranial Window for Repeated In Vivo Imaging in Awake Mice

Presented here is a protocol for the implantation of a chronic cranial window for the longitudinal imaging of brain cells in awake, head-restrained mice.

Implantation of a Cranial Window for Repeated In Vivo Imaging in Awake Mice

To fully understand the cellular physiology of neurons and glia in behaving animals, it is necessary to visualize their morphology and record their ...

The protocol describes how to perform viral injections and implant a cranial window for imaging of brain cells in awake, head-restrained mice. The advantage of this method is that structure and activity of neurons and astrocytes can be imaged repeatedly over multiple sessions. This approach can be used to determine how neural cells are altered in models of neurodevelopmental, or neurodegenerative disorders, or whether experience-dependent plasticity is impaired.Begin by securing an anesthetized mouse to a stereotaxic frame using the snout clamp and ear bars. Using sterile surgical tools, cut and remove the skin from the frontal sutures anterior to the bregma to posteriorly to lambda. Using a sterile size 11 carbon steel surgical blade, gently scrape all the connective tissue from the skull.With the help of a dental drill, gradually drill the skull bone along the outline of the opening in concentric circles to facilitate even thinning of the bone. After each concentric pass, add a drop, or two of saline to the drilled area, and allow the saline to sit for at least 10 seconds before resuming the drilling. Gently push on the central area of the skull bone with fine forceps to check that the skull is adequately thinned and moves.Ensure that the underlying vasculature where the drilling occurred is intact, and that the bone is not cracked. Carefully insert a miniature 15-degree pointed blade into the thinned bone and cut and use the gel foam soaked in saline to stop any bleeds that may occur. Using forceps, carefully lift and remove the bone, taking care to not damage the dura mater.For the injection, fill a sterile beveled glass pipette with a 20-micrometer tip with the virus mixture. Then lower the pipette to touch the surface of the brain, and continue to lower for an additional 200 to 300 micrometers for layer 2/3 injections. Using an intracellular microinjection dispense system, pressure inject the system 12 to 15 times over two minutes.For the cranial window implantation, place the cover glass over the opening in the skull. Use forceps to ensure that the glass is flush over the opening. To seal the edges of the glass window to the skull, apply cyanoacrylate adhesive gel around the perimeter of the glass surface.Over the adhesive gel, apply a layer of glue. Then add a layer of dental cement liquid. When dental cement hardens, apply a thin layer of glue around the central opening of the helicopter type head plate, and place the helicopter type head plate of the appropriate size over the cover glass.Allow the glue to dry. Add dental cement powder in a 1.5-milliliter microfuge tube up to the 0.1 milliliter mark. Mix seven to eight drops of fast-curing instant adhesive into the powder, and draw the resultant mixture into a one-milliliter syringe with a 19 gauge needle that has been cut to create a larger opening.Inject the powder mixture through the lateral holes of the helicopter bar until it seeps from either side. Apply the dental cement adhesive mixture to the rest of the exposed skull to fasten the head plate to the skull. Wrap the mouse in cloth, and secure it via its head plate to the head fixation arm of the airlifted home cage, then leave the home cage exposed to light.After a habituation time of 15 minutes, remove the mouse from the home cage. Using the wide field mode of the microscope, select two to three positions of easily identifiable vasculature. Save the images of the blood vessels, and record the x and y-coordinates that appear on the motor controller.Image the synaptic structures of neurons, and GCaMP6f activity in astrocytes. In the representative analysis, the quality of the cranial window was evaluated with repeated imaging of dendrites and GCaMP6f-expressing astrocytes over days. In a good window, the neuronal structures appeared crisp with clearly visible dendritic spines.Two new spines appeared on day two of imaging. Only one spine persisted and was visible on day five. Calcium activity was studied in astrocytes expressing GCaMP6f at different time points.A global event encompassing the entire cell was witnessed during a locomotion bout. The two critical steps of this protocol are that the bone needs to be adequately thinned prior to removal of the bone, and the proper placement of the cover glass over the opening. Imaging can be combined with behavioral analysis, either during imaging, or post-behavior, such as learning a new motor skill, to determine how neuronal and astrocyte structure and function is modulated by learning.

implantation-cranial-window-for-repeated-vivo-imaging-awake

Research

JoVE Journal

Neuroscience

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.

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

Multimodal Imaging of Stem Cell Implantation in the Central Nervous System of Mice

During the past decade, stem cell transplantation has gained increasing interest as primary or secondary therapeutic modality for a variety of diseases, both in preclinical and clinical studies. However, to date results regarding functional outcome and/or tissue regeneration following stem cell transplantation are quite diverse. Generally, a clinical benefit is observed without profound understanding of the underlying mechanism(s)1. Therefore, multiple efforts have led to the development of different molecular imaging modalities to monitor stem cell grafting with the ultimate aim to accurately evaluate survival, fate and physiology of grafted stem cells and/or their micro-environment. Changes observed in one or more parameters determined by molecular imaging might be related to the observed clinical effect. In this context, our studies focus on the combined use of bioluminescence imaging (BLI), magnetic resonance imaging (MRI) and histological analysis to evaluate stem cell grafting.
BLI is commonly used to non-invasively perform cell tracking and monitor cell survival in time following transplantation2-7, based on a biochemical reaction where cells expressing the Luciferase-reporter gene are able to emit light following interaction with its substrate (e.g. D-luciferin)8, 9. MRI on the other hand is a non-invasive technique which is clinically applicable10 and can be used to precisely locate cellular grafts with very high resolution11-15, although its sensitivity highly depends on the contrast generated after cell labeling with an MRI contrast agent. Finally, post-mortem histological analysis is the method of choice to validate research results obtained with non-invasive techniques with highest resolution and sensitivity. Moreover end-point histological analysis allows us to perform detailed phenotypic analysis of grafted cells and/or the surrounding tissue, based on the use of fluorescent reporter proteins and/or direct cell labeling with specific antibodies.
In summary, we here visually demonstrate the complementarities of BLI, MRI and histology to unravel different stem cell- and/or environment-associated characteristics following stem cell grafting in the CNS of mice. As an example, bone marrow-derived stromal cells, genetically engineered to express the enhanced Green Fluorescent Protein (eGFP) and firefly Luciferase (fLuc), and labeled with blue fluorescent micron-sized iron oxide particles (MPIOs), will be grafted in the CNS of immune-competent mice and outcome will be monitored by BLI, MRI and histology (Figure 1).

This article describes an optimized sequence of events for multimodal imaging of cellular grafts in rodent brain using: (i) in vivo bioluminescence and magnetic resonance imaging, and (ii) post mortem histological analysis. Combining these imaging modalities on a single animal allows cellular graft evaluation with high resolution, sensitivity and specificity.

During the past decade, stem cell transplantation has gained increasing interest as primary or secondary therapeutic modality for a variety of diseases, ...

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

Optical coherence tomography (OCT) is a biomedical imaging technique with high spatial-temporal resolution. With its minimally invasive approach OCT has been used extensively in ophthalmology, dermatology, and gastroenterology1-3. Using a thinned-skull cortical window (TSCW), we employ spectral-domain OCT (SD-OCT) modality as a tool to image the cortex in vivo. Commonly, an opened-skull has been used for neuro-imaging as it provides more versatility, however, a TSCW approach is less invasive and is an effective mean for long term imaging in neuropathology studies. Here, we present a method of creating a TSCW in a mouse model for in vivo OCT imaging of the cerebral cortex.

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

We present a method of creating a thinned-skull cortical window (TSCW) in a mouse model for in vivo OCT imaging of the cerebral cortex.

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

Lateral Chronic Cranial Window Preparation Enables In Vivo Observation Following Distal Middle Cerebral Artery Occlusion in Mice

Focal cerebral ischemia (i.e., ischemic stroke) may cause major brain injury, leading to a severe loss of neuronal function and consequently to a host of motor and cognitive disabilities. Its high prevalence poses a serious health burden, as stroke is among the principal causes of long-term disability and death worldwide1. Recovery of neuronal function is, in most cases, only partial. So far, treatment options are very limited, in particular due to the narrow time window for thrombolysis2,3. Determining methods to accelerate recovery from stroke remains a prime medical goal; however, this has been hampered by insufficient mechanistic insights into the recovery process. Experimental stroke researchers frequently employ rodent models of focal cerebral ischemia. Beyond the acute phase, stroke research is increasingly focused on the sub-acute and chronic phase following cerebral ischemia. Most stroke researchers apply permanent or transient occlusion of the MCA in mice or rats. In patients, occlusions of the MCA are among the most frequent causes of ischemic stroke4. Besides proximal occlusion of the MCA using the filament model, surgical occlusion of the distal MCA is probably the most frequently used model in experimental stroke research5. Occlusion of a distal (to the branching of the lenticulo-striate arteries) MCA branch typically spares the striatum and primarily affects the neocortex. Vessel occlusion can be permanent or transient. High reproducibility of lesion volume and very low mortality rates with respect to the long-term outcome are the main advantages of this model. Here, we demonstrate how to perform a chronic cranial window (CW) preparation lateral to the sagittal sinus, and afterwards how to surgically induce a distal stroke underneath the window using a craniotomy approach. This approach can be applied for sequential imaging of acute and chronic changes following ischemia via epi-illuminating, confocal laser scanning, and two-photon intravital microscopy.

Lateral Chronic Cranial Window Preparation Enables In Vivo Observation Following Distal Middle Cerebral Artery Occlusion in Mice

Surgical occlusion of a distal middle cerebral artery branch (MCAo) is a frequently used model in experimental stroke research. This manuscript describes the basic technique of permanent MCAo, combined with the insertion of a lateral cranial window, which offers the opportunity for longitudinal intravital microscopy in mice.

Focal cerebral ischemia (i.e., ischemic stroke) may cause major brain injury, leading to a severe loss of neuronal function and consequently to a host of ...

Piezo High Accuracy Surgical Osteal Removal (PHASOR): A Technique for Improved Cranial Window Surgery in Mice

Multiphoton microscopy has been widely adapted for imaging neurons in vivo. Repeated imaging requires implantation of a cranial window or repeated thinning of the skull. Cranial window surgery is typically performed with a high speed rotary drill, and many investigators find it challenging to prevent the drill from damaging the delicate dura and blood vessels. Extensive training and practice is required to remove the bone without damage to underlying tissue and thus cranial window surgery can be difficult, time consuming, and produce tissue damage. Piezoelectric surgery, which is extensively used for maxillofacial and dental surgery, utilizes ultrasonic vibrations to remove bone without damaging soft tissues. We have developed a method applying piezoelectric surgery to improve cranial window surgery in mice in preparation for multiphoton imaging. Comparisons within our lab find that the method requires less surgery time and has a lower average rate of complications due to dural bleeding than cranial window surgery with a rotary drill.

Piezo High Accuracy Surgical Osteal Removal PHASOR: A Technique for Improved Cranial Window Surgery in Mice

Piezoelectric surgery has led to improvements in human maxillofacial and dental surgery. We have developed a protocol to optimize piezoelectric surgery for cranial window surgery in mice.

Multiphoton microscopy has been widely adapted for imaging neurons in vivo. Repeated imaging requires implantation of a cranial window or repeated ...

Laminectomy and Spinal Cord Window Implantation in the Mouse

This protocol describes a method for spinal cord laminectomy and glass window implantation for in vivo imaging of the mouse spinal cord. An integrated digital vaporizer is utilized to achieve a stable plane of anesthesia at a low-flow rate of isoflurane. A single vertebral spine is removed, and a commercially available cover-glass is overlaid on a thin agarose bed. A 3D-printed plastic backplate is then affixed to the adjacent vertebral spines using tissue adhesive and dental cement. A stabilization platform is used to reduce motion artifact from respiration and heartbeat. This rapid and clamp-free method is well-suited for acute multi-photon fluorescence microscopy. Representative data are included for an application of this technique to two-photon microscopy of the spinal cord vasculature in transgenic mice expressing eGFP:Claudin-5 &#8212; a tight junction protein.

This protocol describes implantation of a glass window onto the spinal cord of a mouse to facilitate visualization by intravital microscopy.

This protocol describes a method for spinal cord laminectomy and glass window implantation for in vivo imaging of the mouse spinal cord. An integrated ...

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.

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 ...

In vivo Calcium Imaging in Mouse Inferior Olive

Inferior olive (IO), a nucleus in the ventral medulla, is the only source of climbing fibers that form one of the two input pathways entering the cerebellum. IO has long been proposed to be crucial for motor control and its activity is currently considered to be at the center of many hypotheses of both motor and cognitive functions of the cerebellum. While its physiology and function have been relatively well studied on single-cell level in vitro, presently there are no reports on the organization of the IO network activity in living animals. This is largely due to the extremely challenging anatomical location of the IO, making it difficult to subject to conventional fluorescent imaging methods, where an optic path must be created through the entire brain located dorsally to the region of interest.
Here we describe an alternative method for obtaining state-of-the-art -level calcium imaging data from the IO network. The method takes advantage of the extreme ventral location of the IO and involves a surgical procedure for inserting a gradient-refractive index (GRIN) lens through the neck viscera to come into contact with the ventral surface of the calcium sensor GCaMP6s-expressing IO in anesthetized mice. A representative calcium imaging recording is shown to demonstrate the feasibility to record IO neuron activity after the surgery. While this is a non-survival surgery and the recordings must be conducted under anesthesia, it avoids damage to life-critical brainstem nuclei and allows conducting large variety of experiments investigating spatiotemporal activity patterns and input integration in the IO. This procedure with modifications could be used for recordings in other, adjacent regions of the ventral brainstem.

In vivo Calcium Imaging in Mouse Inferior Olive

We present a protocol to expose the brainstem of adult mouse from the ventral side. By using a gradient-refractive index lens with a miniature microscope, calcium imaging can be used to examine the activity of inferior olive neural somata in vivo.

Inferior olive (IO), a nucleus in the ventral medulla, is the only source of climbing fibers that form one of the two input pathways entering the ...

Simultaneous Imaging of Microglial Dynamics and Neuronal Activity in Awake Mice

Since brain functions are under the continuous influence of the signals derived from peripheral tissues, it is critical to elucidate how glial cells in the brain sense various biological conditions in the periphery and transmit the signals to neurons. Microglia, immune cells in the brain, are involved in synaptic development and plasticity. Therefore, the contribution of microglia to neural circuit construction in response to the internal state of the body should be tested critically by intravital imaging of the relationship between microglial dynamics and neuronal activity.
Here, we describe a technique for the simultaneous imaging of microglial dynamics and neuronal activity in awake mice. Adeno-associated virus encoding R-CaMP, a gene-encoded calcium indicator of red fluorescence protein, was injected into layer 2/3 of the primary visual cortex in CX3CR1-EGFP transgenic mice expressing EGFP in microglia. After viral injection, a cranial window was installed onto the brain surface of the injected region. In vivo two-photon imaging in awake mice 4 weeks after the surgery demonstrated that neural activity and microglial dynamics could be recorded simultaneously at the sub-second temporal resolution. This technique can uncover the coordination between microglial dynamics and neuronal activity, with the former responding to peripheral immunological states and the latter encoding the internal brain states.

Here, we describe a protocol combining adeno-associated virus injection with cranial window implantation for simultaneous imaging of microglial dynamics and neuronal activity in awake mice.

Since brain functions are under the continuous influence of the signals derived from peripheral tissues, it is critical to elucidate how glial cells in ...

In Vivo Wide-Field and Two-Photon Calcium Imaging from a Mouse Using a Large Cranial Window

Wide-field calcium imaging from the mouse&#39;s neocortex allows one to observe cortex-wide neural activity related to various brain functions. On the other hand, two-photon imaging can resolve the activity of local neural circuits at the single-cell level. It is critical to make a large cranial window to perform multiple-scale analysis using both imaging techniques in the same mouse. To achieve this, one must remove a large section of the skull and cover the exposed cortical surface with transparent materials. Previously, glass skulls and polymer-based cranial windows have been developed for this purpose, but these materials are not easily fabricated. The present protocol describes a simple method for making a large cranial window consisting of commercially available polyvinylidene chloride (PVDC) wrapping film, a transparent silicone plug, and a cover glass. For imaging the dorsal surface of an entire hemisphere, the window size was approximately 6 x 3 mm2. Severe brain vibrations were not observed regardless of such a large window. Importantly, the condition of the brain surface did not deteriorate for more than one month. Wide-field imaging of a mouse expressing a genetically-encoded calcium indicator (GECI), GCaMP6f, specifically in astrocytes, revealed synchronized responses in a few millimeters. Two-photon imaging of the same mouse showed prominent calcium responses in individual astrocytes over several seconds. Furthermore, a thin layer of an adeno-associated virus was applied to the PVDC film and successfully expressed GECI in cortical neurons over the cranial window. This technique is reliable and cost-effective for making a large cranial window and facilitates the investigation of the neural and glial dynamics and their interactions during behavior at the macroscopic and microscopic levels.

In Vivo Wide-Field and Two-Photon Calcium Imaging from a Mouse Using a Large Cranial Window

The present protocol describes making a large (6 x 3 mm2) cranial window using food wrap, transparent silicone, and cover glass. This cranial window allows in vivo wide-field and two-photon calcium imaging experiments in the same mouse.

Wide-field calcium imaging from the mouse&#39;s neocortex allows one to observe cortex-wide neural activity related to various brain functions. On the ...