Name: laser-induced brain injury in the motor cortex of rats
Uploaded: 2020-09-26T12:30:00
Description: Watch this Scientific Journal Video about Laser-Induced Brain Injury in the Motor Cortex of Rats at JoVE.com

We would like to thank the Department of Anesthesiology of Soroka University Medical Center and the laboratory staff of Ben-Gurion University of the Negev for their help in the performance of this experiment.

The following procedure was conducted according to the Guidelines of the Use of Experimental Animals of the European Community. The experiments were also approved by the Animal Care Committee at the Ben-Gurion University of the Negev.
1. Animal selection and preparation
<ol>
	<li>Select 65 male Sprague-Dawley rats weighing 300 to 350 g with no overt pathology for this procedure. The smaller size poses technical difficulties for the MCAO procedure.</li>
	<li>Assign 3 rats per cage and let the...

<ol>
	<li>World Health Organization. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Global+health+estimates:+deaths+by+cause,+age,+sex+and+country,+2000-2012.">Global health estimates: deaths by cause, age, sex and country, 2000-2012.</a> World Health Organization. 9, (2014).</li><li>Meadows, K. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+models+of+focal+and+multifocal+cerebral+ischemia:+a+review.">Experimental models of focal and multifocal cerebral ischemia: a review.</a> Reviews in the Neurosciences. 29, 661-674 (2018).</li><li>Durukan, A., Strbian, D., Tatlisumak, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rodent+models+of+ischemic+stroke:+a+useful+tool+for+stroke+drug+development.">Rodent models of ischemic stroke: a useful tool for stroke drug development.</a> Current Pharmaceutical Designs. 14, 359-370 (2008).</li><li>Fluri, F., Schuhmann, M. K., Kleinschnitz, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+ischemic+stroke+and+their+application+in+clinical+research.">Animal models of ischemic stroke and their application in clinical research.</a> Drug Design, Development and Therapy. 9, 3445-3454 (2015).</li><li>Li, F., Omae, T., Fisher, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spontaneous+hyperthermia+and+its+mechanism+in+the+intraluminal+suture+middle+cerebral+artery+occlusion+model+of+rats.">Spontaneous hyperthermia and its mechanism in the intraluminal suture middle cerebral artery occlusion model of rats.</a> Stroke. 30, 2464-2470 (1999).</li><li>Boyko, M., 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=An+experimental+model+of+focal+ischemia+using+an+internal+carotid+artery+approach.">An experimental model of focal ischemia using an internal carotid artery approach.</a> Journal of Neuroscience Methods. 193, 246-253 (2010).</li><li>Zhao, Q., Memezawa, H., Smith, M. L., Siesjo, B. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hyperthermia+complicates+middle+cerebral+artery+occlusion+induced+by+an+intraluminal+filament.">Hyperthermia complicates middle cerebral artery occlusion induced by an intraluminal filament.</a> Brain Research. 649, 253-259 (1994).</li><li>Braeuninger, S., Kleinschnitz, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rodent+models+of+focal+cerebral+ischemia:+procedural+pitfalls+and+translational+problems.">Rodent models of focal cerebral ischemia: procedural pitfalls and translational problems.</a> Experimental and Translational Stroke Medicine. 1, 8 (2009).</li><li>Choi, B. I., 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=Neurobehavioural+deficits+correlate+with+the+cerebral+infarction+volume+of+stroke+animals:+a+comparative+study+on+ischaemia-reperfusion+and+photothrombosis+models.">Neurobehavioural deficits correlate with the cerebral infarction volume of stroke animals: a comparative study on ischaemia-reperfusion and photothrombosis models.</a> Environmental Toxicology and Pharmacology. 33, 60-69 (2012).</li><li>Boyko, M., 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=An+Alternative+Model+of+Laser-Induced+Stroke+in+the+Motor+Cortex+of+Rats.">An Alternative Model of Laser-Induced Stroke in the Motor Cortex of Rats.</a> Biological Procedure Online. 21, 9 (2019).</li><li>Bleilevens, C., 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=Effect+of+anesthesia+and+cerebral+blood+flow+on+neuronal+injury+in+a+rat+middle+cerebral+artery+occlusion+(MCAO)+model.">Effect of anesthesia and cerebral blood flow on neuronal injury in a rat middle cerebral artery occlusion (MCAO) model.</a> Experimental Brain Research. 224, 155-164 (2013).</li><li>Kuts, R., 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=A+Middle+Cerebral+Artery+Occlusion+Technique+for+Inducing+Post-stroke+Depression+in+Rats.">A Middle Cerebral Artery Occlusion Technique for Inducing Post-stroke Depression in Rats.</a> Journal of Visualized Experiments. (147), e58875 (2019).</li><li>Boyko, M., 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=Morphological+and+neuro-behavioral+parallels+in+the+rat+model+of+stroke.">Morphological and neuro-behavioral parallels in the rat model of stroke.</a> Behavioural Brain Research. 223, 17-23 (2011).</li></ol>

It is fair to assume that the laser technique is minimally invasive, given that no deaths or SAH occurred in the laser group. The primary cause of death and SAH is the damage to blood vessels that leads to an elevation of intracranial pressure (ICP), as shown in the original MCAO techniques10. The absence of death and SAH in the laser group is likely due to the specific effects of lasers: they do not have direct impact on blood vessels and can induce coagulation in case of leakage. Low infarct vol...

An erratum was issued for:&#160;<a href="https://www.jove.com/t/60928">Laser-Induced Brain Injury in the Motor Cortex of Rats</a>. The Authors section was updated.
One of the author names was updated from:
Dmitri Frank
to
Dmitry Frank

An erratum was issued for:&#160;<a href="https://www.jove.com/t/60928">Laser-Induced Brain Injury in the Motor Cortex of Rats</a>. The Authors section was updated.

Erratum: Laser-Induced Brain Injury in the Motor Cortex of Rats

Globally, stroke is the second leading cause of death and the third leading cause of disability1. Stroke also leads to severe disability, often requiring extra care from medical staff and relatives. There is, therefore, a need to understand the complications associated with the disorder and improve the potential for more positive outcomes.&#160;
The use of animal models is the initial step to understanding diseases. To ensure the best research outcomes, a typical model would include a simple technique, affordability, high reproducibility, and minimal variability. The determinants in ischemic stroke models include brain edema volume, infarct size, the extent of the blood-brain barrier (BBB) breakdown, and functional impairment generally evaluated via neurological severity score2.
The most widely used stroke induction technique in rodent models occludes the middle cerebral artery (MCA) transiently or permanently3. This technique produces a stroke model similar to the ones in humans: it has a penumbra surrounding the stroked area, is highly reproducible, and regulates ischemia duration and reperfusion4. Nevertheless, the MCAO method has some complications. The technique is prone to intracranial hemorrhage and injury to the ipsilateral retina with a dysfunction of the visual cortex and common hyperthermia that often lead to additional outcomes5,6,7. Other limitations include high variations in induced stroke (arising from the probable extension of the ischemia to unintended regions, like the external carotid artery region), insufficient occlusion of the MCA, and premature reperfusion. Also, rats of different strains and sizes exhibit various infarct volumes8. In addition to all the disadvantages mentioned, MCAO model cannot induce small isolated strokes in deep brain areas, because it is limited technically in terms of its requirement of minimum vessel size for catheterization. This makes the need for an alternative model all the more critical. Another method, photothrombosis, provides a possible alternative to MCAO procedures but does not improve on the efficiency9. This technique targets stroke with light and offers some improvements on the previous models. However, photothrombosis requires an invasive craniotomy that is associated with secondary compications9.
In the light of outlined shortcomings, the protocol presented here provides a capable alternative laser technique for inducing brain injury in rodents. The mechanism of action of the laser technique is based on the laser&#8217;s photothermal effects imparted on living tissues, which leads to the absorption of light beams by body tissues and their conversion into heat. The advantages of using a laser technique are its safety and ease of manipulation. A laser&#8217;s ability to produce heat to stop bleeding makes it very important in medicine, while its ability to amplify different beams at a given meet point ensures that lasers avoid destroying healthy tissues that stands in the&#160;way of&#160;the&#160;target point10. The laser beam used in this protocol can pass through a low liquid medium, such as bone, without emitting its energy and/or causing any destruction. Once it reaches a high liquid medium, such as brain tissues, it uses up its energy to destroy the target tissues. The technique, therefore, can induce brain injury only in the appropriate area of the brain.
The technique presented here showed a tremendous amount of ability to regulate its levels of irradiation, producing the chosen variations of brain injury intended from the start. Unlike the original MCAO that impacts both the cortex and striatum, the laser technique was able to regulate the impact of brain injury, inducing injury only on the intended motor cortex. Herein, the laser-induced brain injury protocol and a summary of representative results for the procedure performed on the cerebral cortex of rats are provided.

<table border="0" cellpadding="0" cellspacing="0" style="width:667px;" width="666">
	<tbody>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">2,3,5-Triphenyltetrazolium chloride</td>
			<td style="width:123px;">SIGMA - ALDRICH</td>
			<td style="width:161px;">298-96-4</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">50% trichloroacetic acid</td>
			<td style="width:123px;">SIGMA - ALDRICH</td>
			<td style="width:161px;">76-03-9</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Brain &#38; Tissue Matrices</td>
			<td style="width:123px;">SIGMA - ALDRICH</td>
			<td>15013</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Cannula Venflon 22 G</td>
			<td style="width:123px;">KD-FIX</td>
			<td style="width:161px;">1.83604E+11</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Centrifuge Sigma 2-16P</td>
			<td style="width:123px;">SIGMA - ALDRICH</td>
			<td style="width:161px;">Sigma 2-16P</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Compact Analytical Balances</td>
			<td style="width:123px;">SIGMA - ALDRICH</td>
			<td style="width:161px;">HR-AZ/HR-A</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Digital Weighing Scale</td>
			<td style="width:123px;">SIGMA - ALDRICH</td>
			<td style="width:161px;">Rs 4,000</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Dissecting scissors</td>
			<td style="width:123px;">SIGMA - ALDRICH</td>
			<td style="width:161px;">Z265969</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Eppendorf pipette</td>
			<td style="width:123px;">SIGMA - ALDRICH</td>
			<td style="width:161px;">Z683884</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Eppendorf Tube</td>
			<td style="width:123px;">SIGMA - ALDRICH</td>
			<td>EP0030119460</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Ethanol 96 %</td>
			<td style="width:123px;">ROMICAL</td>
			<td style="width:161px;"></td>
			<td>Flammable Liquid</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Evans Blue 2%</td>
			<td style="width:123px;">SIGMA - ALDRICH</td>
			<td style="width:161px;">314-13-6</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Fluorescence detector</td>
			<td style="width:123px;">Tecan, M&#228;nnedorf Switzerland</td>
			<td style="width:161px;">model Infinite 200 PRO multimode reader</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Heater with thermometer</td>
			<td>Heatingpad-1</td>
			<td>Model: HEATINGPAD-1/2</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Infusion Cuff</td>
			<td style="width:123px;">ABN</td>
			<td style="width:161px;">IC-500</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Isofluran, USP 100%</td>
			<td style="width:123px;">Piramamal Critical Care, Inc</td>
			<td style="width:161px;">NDC 66794-017</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Multiset</td>
			<td style="width:123px;">TEVA MEDICAL</td>
			<td style="width:161px;">998702</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Olympus BX 40 microscope</td>
			<td style="width:123px;">Olympus</td>
			<td style="width:161px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Optical scanner</td>
			<td style="width:123px;">Canon</td>
			<td style="width:161px;">Cano Scan 4200F</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Petri dishes</td>
			<td style="width:123px;">SIGMA - ALDRICH</td>
			<td style="width:161px;">P5606</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Scalpel blades 11</td>
			<td style="width:123px;">SIGMA - ALDRICH</td>
			<td style="width:161px;">S2771</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Sharplan 3000 Nd:YAG (neodymium-doped yttrium aluminum garnet) laser machine</td>
			<td style="width:123px;">Laser Industries Ltd</td>
			<td style="width:161px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Stereotaxic head holder</td>
			<td style="width:123px;">KOPF</td>
			<td style="width:161px;">900LS</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:43px;width:216px;">Sterile Syringe 2 ml</td>
			<td style="width:123px;">Braun</td>
			<td>4606027V</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Syringe-needle 27 G</td>
			<td style="width:123px;">Braun</td>
			<td style="width:161px;">305620</td>
			<td></td>
		</tr>
	</tbody>
</table>

laser-induced brain injury in the motor cortex of rats

A common technique for inducing stroke in experimental rodent models involves the transient (often denoted as MCAO-t) or permanent (designated as MCAO-p) occlusion of the middle cerebral artery (MCA) using a catheter. This generally accepted technique, however, has some limitations, thereby limiting its extensive use. Stroke induction by this method is often characterized by high variability in the localization and size of the ischemic area, periodical occurrences of hemorrhage, and high death rates. Also, the successful completion of any of the transient or permanent procedures requires expertise and often lasts for about 30 minutes. In this protocol, a laser irradiation technique is presented that can serve as an alternative method for inducing and studying brain injury in rodent models.
When compared to rats in the control and MCAO groups, the brain injury by laser induction showed reduced variability in body temperature, infarct volume, brain edema, intracranial hemorrhage, and mortality. Furthermore, the use of a laser-induced injury caused damage to the brain tissues only in the motor cortex unlike in the MCAO experiments where destruction of both the motor cortex and striatal tissues is observed.
Findings from this investigation suggest that laser irradiation could serve as an alternative and effective technique for inducing brain injury in the motor cortex. The method also shortens the time for completing the procedure and does not require expert handlers.

No deaths or SAH were registered in either the control or experimental groups (Table 1). The MCAO group had a 20% rate of both mortality and SAH.
The relative body temperature changes in the rats of both groups were also similar, despite a difference in the variability of both groups (Table 1).
There was a significantly worse NSS in both the laser (16 &#177; 1.1) and MCAO (20 &#177; 1.5) models, compared to the sham-operated control...

Watch this Scientific Journal Video about Laser-Induced Brain Injury in the Motor Cortex of Rats at JoVE.com

Laser-Induced Brain Injury in the Motor Cortex of Rats

The protocol presented here shows a technique to create a rodent model of brain injury. The method described here uses laser irradiation and targets motor cortex.

A common technique for inducing stroke in experimental rodent models involves the transient (often denoted as MCAO-t) or permanent (designated as MCAO-p) ...

Our protocol provides a novel methodology for creating traumatic brain injury in rats using laser irradiation to create a focus impact in the motor cortex. The main advantage of this technique are the low variability in infarct area, the low mortality rates, and the relative simplicity of the procedure which doesn't require expert handlers. Demonstrating the procedure will be Dmitry Natanel, a researcher from our laboratory.To perform a laser-induced brain injury, first assign 20, 300 to 350 gram Sprague Dawley rats into the laser group and 20 to the control Sham-operated group. After confirming a lack of response to withdrawal reflex, place one rat on a rectal temperature regulated heating pad and use a shaver to remove enough hair from the injury site with an approximately two centimeter hair-free margin around the incision. Disinfect the exposed skin with 70%ethanol and place the rat in the prone position in a stereotaxic head holder.Make a three centimeter incision to allow lateral reflection of the scalp to expose the area between bregma and lambda. Holding an Nd:YAG laser with peak wavelength of 1064 nanometers at a two millimeter distance from the skull, administer 50 joules times 10 points with a one-second pulse duration to the exposed area of the skull above the right hemisphere. After the laser injury has been delivered, remove the rat from the device and close the scalp with 3-0 silk surgical sutures.Then, place the rat in its cage with monitoring until full recumbency. 24 hours after the procedure, use a 43 point scoring system to evaluate the neurological severity score. Testing the animals for neurological deficits, behavior disturbances, beam balancing task, and reflexes, and assigning higher scores for more severe disabilities.After the assessment, harvest the brains from each experimental and control animal according to standard protocols. To assess the brain infarct volume, section the harvested brains into six two millimeter thick coronal slices and incubate each slice in 0.05%TTC for 30 minutes at 37 degrees Celsius. Following staining, scan this slices with an optical scanner with a 1600 by 1600 dots per inch resolution.The unstained areas of the fixed brain slices are defined as infarcted. To evaluate the incidence of blood brain barrier breakage, 24 hours after the laser induced injury load a syringe with 2%Evans blue dye diluted in four milliliters per kilogram of saline solution and deliver the solution intravenously to the injured and control rats via the cannulated tail vein. Allow the solution to circulate for one hour before using surgical pincets and scissors to open the chest of the first animal.Perfuse the exposed heart with cooled 0.9%saline via the left ventricle at 110 millimeters of mercury of pressure until a colorless profusion liquid is observed from the right atrium. Next, harvest the brain and obtain two millimeter rostral caudal slices. Separate the left brain slices from the right brain slices to allow evaluation of the injured and non-injured hemispheres separately, and weigh the samples.Homogenize the samples using a mortar and pestle and incubate the tissue samples in 50%trichloroacetic acid for 24 hours. The next day, centrifuge the homogenized brain tissue samples for 20 minutes at 10, 000 times G and room temperature, and mix one milliliter of the supernatant with 1.5 milliliters of 96%ethanol at one to three ratio. Then, use a fluorescence detector at a 620 nanometer excitation and the 680 nanometer emission wavelength to assess the blood brain barrier breakage.As observed by histological analysis, Evans blue staining can be used to reveal the incidence of brain injury at laser and MCAO model animals. In this representative analysis no deaths or subarachnoid hemorrhages were registered in either the control or experimental groups, and the MCAO group had a 20%rate of both mortality and subarachnoid hemorrhage. The relative body temperature changes in the rats from both groups were also similar, despite a difference in the variability of both groups.The neurological severity scores were significantly worse in both the laser and MCAO models compared to the Sham-operated control group. Laser-induced to brain injury also caused a significant increase in infarct volume at the target hemisphere compared to the Sham-operated control group. However, the infarct volume of the laser model was smaller compared to the animals injured by the MCAO technique.No difference in brain edema was observed between the laser-induced brain injury model and the Sham-operated control group. However, there was a significant difference in brain edema between the laser model and MCAO injured groups. Compared to the Sham-operated control group, the laser-induced brain injury and MCAO techniques both caused a significant increase in blood brain barrier breakage at the non-injured and target hemispheres.While attempting this model, remember to precisely target the motor cortex area and to standardize the energy, the number of points being irradiated, and the total exposition time. Following this procedure, a wide plethora of behavioral tests, such as beam walking, Froedert, and other evaluations can be performed.

laser-induced-brain-injury-in-the-motor-cortex-of-rats

Research

JoVE Journal

Neuroscience

Live Imaging of Mitosis in the Developing Mouse Embryonic Cortex

Although of short duration, mitosis is a complex and dynamic multi-step process fundamental for development of organs including the brain. In the developing cerebral cortex, abnormal mitosis of neural progenitors can cause defects in brain size and function. Hence, there is a critical need for tools to understand the mechanisms of neural progenitor mitosis. Cortical development in rodents is an outstanding model for studying this process. Neural progenitor mitosis is commonly examined in fixed brain sections. This protocol will describe in detail an approach for live imaging of mitosis in ex vivo embryonic brain slices. We will describe the critical steps for this procedure, which include: brain extraction, brain embedding, vibratome sectioning of brain slices, staining and culturing of slices, and time-lapse imaging. We will then demonstrate and describe in detail how to perform post-acquisition analysis of mitosis. We include representative results from this assay using the vital dye Syto11, transgenic mice (histone H2B-EGFP and centrin-EGFP), and in utero electroporation (mCherry-&#945;-tubulin). We will discuss how this procedure can be best optimized and how it can be modified for study of genetic regulation of mitosis. Live imaging of mitosis in brain slices is a flexible approach to assess the impact of age, anatomy, and genetic perturbation in a controlled environment, and to generate a large amount of data with high temporal and spatial resolution. Hence this protocol will complement existing tools for analysis of neural progenitor mitosis.

Neural progenitor mitosis is a critical parameter of neurogenesis. Much of our understanding of neural progenitor mitosis is based on analysis of fixed tissue. Live imaging in embryonic brain slices is a versatile technique to assess mitosis with high temporal and spatial resolution in a controlled environment.

Although of short duration, mitosis is a complex and dynamic multi-step process fundamental for development of organs including the brain. In the ...

An Ex Vivo Laser-induced Spinal Cord Injury Model to Assess Mechanisms of Axonal Degeneration in Real-time

Injured CNS axons fail to regenerate and often retract away from the injury site. Axons spared from the initial injury may later undergo secondary axonal degeneration. Lack of growth cone formation, regeneration, and loss of additional myelinated axonal projections within the spinal cord greatly limits neurological recovery following injury. To assess how central myelinated axons of the spinal cord respond to injury, we developed an ex vivo living spinal cord model utilizing transgenic mice that express yellow fluorescent protein in axons and a focal and highly reproducible laser-induced spinal cord injury to document the fate of axons and myelin (lipophilic fluorescent dye Nile Red) over time using two-photon excitation time-lapse microscopy. Dynamic processes such as acute axonal injury, axonal retraction, and myelin degeneration are best studied in real-time. However, the non-focal nature of contusion-based injuries and movement artifacts encountered during in vivo spinal cord imaging make differentiating primary and secondary axonal injury responses using high resolution microscopy challenging. The ex vivo spinal cord model described here mimics several aspects of clinically relevant contusion/compression-induced axonal pathologies including axonal swelling, spheroid formation, axonal transection, and peri-axonal swelling providing a useful model to study these dynamic processes in real-time. Major advantages of this model are excellent spatiotemporal resolution that allows differentiation between the primary insult that directly injures axons and secondary injury mechanisms; controlled infusion of reagents directly to the perfusate bathing the cord; precise alterations of the environmental milieu (e.g., calcium, sodium ions, known contributors to axonal injury, but near impossible to manipulate in vivo); and murine models also offer an advantage as they provide an opportunity to visualize and manipulate genetically identified cell populations and subcellular structures. Here, we describe how to isolate and image the living spinal cord from mice to capture dynamics of acute axonal injury.

An Ex Vivo Laser-induced Spinal Cord Injury Model to Assess Mechanisms of Axonal Degeneration in Real-time

We present a protocol utilizing two-photon excitation time-lapse microscopy to simultaneously visualize the dynamics of axon and myelin injuries in real time. This proposed protocol permits studies of both intrinsic and extrinsic factors which can influence central myelinated axon fate after injury and contribute to permanent clinical disability.

Injured CNS axons fail to regenerate and often retract away from the injury site. Axons spared from the initial injury may later undergo secondary axonal ...

Effects of Transcranial Alternating Current Stimulation on the Primary Motor Cortex by Online Combined Approach with Transcranial Magnetic Stimulation

Transcranial Alternating Current Stimulation (tACS) is a neuromodulatory technique able to act through sinusoidal electrical waveforms in a specific frequency and in turn modulate ongoing cortical oscillatory activity. This neurotool allows the establishment of a causal link between endogenous oscillatory activity and behavior. Most of the tACS studies have shown online effects of tACS. However, little is known about the underlying action mechanisms of this technique because of the AC-induced artifacts on Electroencephalography (EEG) signals. Here we show a unique approach to investigate online physiological frequency-specific effects of tACS of the primary motor cortex (M1) by using single pulse Transcranial Magnetic Stimulation (TMS) to probe cortical excitability changes. In our setup, the TMS coil is placed over the tACS electrode while Motor Evoked Potentials (MEPs) are collected to test the effects of the ongoing M1-tACS. So far, this approach has mainly been used to study the visual and motor systems. However, the current tACS-TMS setup can pave the way for future investigations of cognitive functions. Therefore, we provide a step-by-step manual and video guidelines for the procedure.

Transcranial Alternating Current Stimulation (tACS) allows the modulation of cortical excitability in a frequency-specific fashion. Here we show a unique approach which combines online tACS with single pulse Transcranial Magnetic Stimulation (TMS) in order to "probe" cortical excitability by means of Motor Evoked Potentials.

Transcranial Alternating Current Stimulation (tACS) is a neuromodulatory technique able to act through sinusoidal electrical waveforms in a specific ...

Imaging Neural Activity in the Primary Somatosensory Cortex Using Thy1-GCaMP6s Transgenic Mice

The mammalian brain exhibits marked symmetry across the sagittal plane. However, detailed description of neural dynamics in symmetric brain regions in adult mammalian animals remains elusive. In this study, we describe an experimental procedure for measuring calcium dynamics through dual optical windows above bilateral primary somatosensory corticies (S1) in Thy1-GCaMP6s transgenic mice using 2-photon (2P) microscopy. This method enables recordings and quantifications of neural activity in bilateral mouse brain regions one at a time in the same experiment for a prolonged period in vivo. Key aspects of this method, which can be completed within an hour, include minimally invasive surgery procedures for creating dual optical windows, and the use of 2P imaging. Although we only demonstrate the technique in the S1 area, the method can be applied to other regions of the living brain facilitating the elucidation of structural and functional complexities of brain neural networks.

Imaging Neural Activity in the Primary Somatosensory Cortex Using Thy1-GCaMP6s Transgenic Mice

We describe an experimental procedure for measuring neuronal activity through dual optical windows above bilateral primary somatosensory corticies (S1) in Thy1-GCaMP6s transgenic mice using 2-photon (2P) microscopy in vivo.

The mammalian brain exhibits marked symmetry across the sagittal plane. However, detailed description of neural dynamics in symmetric brain regions in ...

In Vivo Single-Molecule Tracking at the Drosophila Presynaptic Motor Nerve Terminal

An increasing number of super-resolution microscopy techniques are helping to uncover the mechanisms that govern the nanoscale cellular world. Single-molecule imaging is gaining momentum as it provides exceptional access to the visualization of individual molecules in living cells. Here, we describe a technique that we developed to perform single-particle tracking photo-activated localization microscopy (sptPALM) in Drosophila larvae. Synaptic communication relies on key presynaptic proteins that act by docking, priming, and promoting the fusion of neurotransmitter-containing vesicles with the plasma membrane. A range of protein-protein and protein-lipid interactions tightly regulates these processes and the presynaptic proteins therefore exhibit changes in mobility associated with each of these key events. Investigating how mobility of these proteins correlates with their physiological function in an intact live animal is essential to understanding their precise mechanism of action. Extracting protein mobility with high resolution in vivo requires overcoming limitations such as optical transparency, accessibility, and penetration depth. We describe how photoconvertible fluorescent proteins tagged to the presynaptic protein Syntaxin-1A can be visualized via slight oblique illumination and tracked at the motor nerve terminal or along the motor neuron axon of the third instar Drosophila larva.

In Vivo Single-Molecule Tracking at the Drosophila Presynaptic Motor Nerve Terminal

Here we illustrate how single molecule photo-activated localization microscopy can be carried out on the motor nerve terminal of a live Drosophila melanogaster third instar larva.

An increasing number of super-resolution microscopy techniques are helping to uncover the mechanisms that govern the nanoscale cellular world. ...

Evaluation of Hemisphere Lateralization with Bilateral Local Field Potential Recording in Secondary Motor Cortex of Mice

This article demonstrates complete, detailed procedures for both in vivo bilateral recording and analysis of local field potential (LFP) in the cortical areas of mice, which are useful for evaluating possible laterality deficits, as well as for assessing brain connectivity and coupling of neural network activities in rodents. The pathological mechanisms underlying Alzheimer&#39;s disease (AD), a common neurodegenerative disease, remain largely unknown. Altered brain laterality has been demonstrated in aging people, but whether or not abnormal lateralization is one of the early signs of AD has not been determined. To investigate this, we recorded bilateral LFPs in 3-5-month-old AD model mice, APP/PS1, together with littermate wild type (WT) controls. The LFPs of the left and right secondary motor cortex (M2), specifically in the gamma band, were more synchronized in APP/PS1 mice than in WT controls, suggesting a declined hemispheric asymmetry of bilateral M2 in this AD mouse model. Notably, the recording and data analysis processes are flexible and easy to carry out, and can also be applied to other brain pathways when conducting experiments that focus on neuronal circuits.

We present in vivo electrophysiological recording of the local field potential (LFP) in bilateral secondary motor cortex (M2) of mice, which can be applied to evaluate hemisphere lateralization. The study revealed altered levels of synchronization between the left and right M2 in APP/PS1 mice compared to WT controls.

This article demonstrates complete, detailed procedures for both in vivo bilateral recording and analysis of local field potential (LFP) in the cortical ...

Investigating Alterations in Caecum Microbiota After Traumatic Brain Injury in Mice

Increasing evidence shows that the microbiota-gut-brain axis plays an important role in the pathogenesis of brain diseases. Several studies also demonstrate that traumatic brain injuries cause changes to the gut microbiota. However, mechanisms underlying the bidirectional regulation of the brain-gut axis remain unknown. Currently, few models exist for studying the changes in gut microbiota after traumatic brain injury. Therefore, the presented study combines protocols for inducing traumatic brain injury using a lateral fluid percussion device and analysis of caecum samples following injury for investigating alterations in the gut microbiome. Alterations of the gut microbiota composition after traumatic brain injury are determined using 16S-rDNA sequencing. This protocol provides an effective method for studying the relationships between enteric microorganisms and traumatic brain injury.

Presented here is a protocol to induce diffuse traumatic brain injury using a lateral fluid percussion device followed by the collection of the caecum content for gut microbiome analysis.

Increasing evidence shows that the microbiota-gut-brain axis plays an important role in the pathogenesis of brain diseases. Several studies also ...

Non-Invasive Modulation and Robotic Mapping of Motor Cortex in the Developing Brain

Mapping the motor cortex with transcranial magnetic stimulation (TMS) has potential to interrogate motor cortex physiology and plasticity but carries unique challenges in children. Similarly, transcranial direct current stimulation (tDCS) can improve motor learning in adults but has only recently been applied to children. The use of tDCS and emerging techniques like high&#8211;definition tDCS (HD-tDCS) require special methodological considerations in the developing brain. Robotic TMS motor mapping may confer unique advantages for mapping, particularly in the developing brain. Here, we aim to provide a practical, standardized approach for two integrated methods capable of simultaneously exploring motor cortex modulation and motor maps in children. First, we describe a protocol for robotic TMS motor mapping. Individualized, MRI-navigated 12x12 grids centered on the motor cortex guide a robot to administer single-pulse TMS. Mean motor evoked potential (MEP) amplitudes per grid point are used to generate 3D motor maps of individual hand muscles with outcomes including map area, volume, and center of gravity. Tools to measure safety and tolerability of both methods are also included. Second, we describe the application of both tDCS and HD-tDCS to modulate the motor cortex and motor learning. An experimental training paradigm and sample results are described. These methods will advance the application of non-invasive brain stimulation in children.

We demonstrate protocols for the modulation (tDCS, HD-tDCS) and mapping (robotic TMS) of the motor cortex in children.

Mapping the motor cortex with transcranial magnetic stimulation (TMS) has potential to interrogate motor cortex physiology and plasticity but carries ...

Advanced Diffusion Imaging in The Hippocampus of Rats with Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI) is the most common type of acquired brain injury. Since patients with traumatic brain injury show a tremendous variability and heterogeneity (age, gender, type of trauma, other possible pathologies, etc.), animal models play a key role in unraveling factors that are limitations in clinical research. They provide a standardized and controlled setting to investigate the biological mechanisms of injury and repair following TBI. However, not all animal models mimic the diffuse and subtle nature of mTBI effectively. For example, the commonly used controlled cortical impact (CCI) and lateral fluid percussion injury (LFPI) models make use of a craniotomy to expose the brain and induce widespread focal trauma, which are not commonly seen in mTBI. Therefore, these experimental models are not valid to mimic mTBI. Thus, an appropriate model should be used to investigate mTBI. The Marmarou weight drop model for rats induces similar microstructural alterations and cognitive impairments as seen in patients who sustain mild trauma; therefore, this model was selected for this protocol. Conventional computed tomography and magnetic resonance imaging (MRI) scans commonly show no damage following a mild injury, because mTBI induces often only subtle and diffuse injuries. With diffusion weighted MRI, it is possible to investigate microstructural properties of brain tissue, which can provide more insight into the microscopic alterations following mild trauma. Therefore, the goal of this study is to obtain quantitative information of a selected region-of-interest (i.e., hippocampus) to follow up disease progression after obtaining a mild and diffuse brain injury.

The overall goal of this procedure is to obtain quantitative microstructural information of the hippocampus in a rat with mild traumatic brain injury. This is done using an advanced diffusion-weighted magnetic resonance imaging protocol and region-of-interest based analysis of parametric diffusion maps.

Mild traumatic brain injury (mTBI) is the most common type of acquired brain injury. Since patients with traumatic brain injury show a tremendous ...

3D Kinematic Analysis for the Functional Evaluation in the Rat Model of Sciatic Nerve Crush Injury

Compared to the Sciatic Functional Index (SFI), kinematic analysis is a more reliable and sensitive method for performing functional evaluations of sciatic nerve injury rodent models. In this protocol, we describe a novel kinematic analysis method that uses a three-dimensional (3D) motion capture apparatus for functional evaluations using a rat sciatic nerve crush injury model. First, the rat is familiarized with treadmill walking. Markers are then attached to the designated bone landmarks and the rat is made to walk on the treadmill at the desired speed. Meanwhile, the posterior limb movements of the rat are recorded using four cameras. Depending on the software used, marker tracings are created using both automatic and manual modes and the desired data are produced after subtle adjustments. This method of kinematic analysis, which uses a 3D motion capture apparatus, offers numerous advantages, including superior precision and accuracy. Many more parameters can be investigated during the comprehensive functional evaluations. This method has several shortcomings that require consideration: The system is expensive, can be complicated to operate, and may produce data deviations due to skin shifting. Nevertheless, kinematic analysis using a 3D motion capture apparatus is useful for performing functional anterior and posterior limb evaluations. In the future, this method may become increasingly useful for generating accurate assessments of various traumas and diseases.

We introduce a kinematic analysis method that uses a three-dimensional motion capture apparatus containing four cameras and data processing software for performing functional evaluations during fundamental research involving rodent models.

Compared to the Sciatic Functional Index (SFI), kinematic analysis is a more reliable and sensitive method for performing functional evaluations of ...