Name: inducing post-traumatic epilepsy in a mouse model of repetitive diffuse traumatic brain injury
Uploaded: 2020-02-10T12:30:00
Description: Watch this Scientific Journal Video about Inducing Post-Traumatic Epilepsy in a Mouse Model of Repetitive Diffuse Traumatic Brain Injury at JoVE.com

This work was supported by R01 NS105807/NS/NINDS NIH HHS/United States and CURE based on a grant CURE received from the United States Army Medical Research and Materiel Command, Department of Defense (DoD), through the Psychological Health and Traumatic Brain Injury Research Program under Award No. W81XWH-15-2-0069. Ivan Zuidhoek is greatly appreciated for proofreading the manuscript.

All animal procedures described in this protocol were performed in accordance with the Institutional Animal Care and Use Committee (IACUC) of Virginia Tech and in compliance with the National Institutes of Health&#39;s &#39;Guide for the Care and Use of Laboratory Animals&#39;.
1. Animal handling protocol
NOTE: This protocol is intended to habituate animals ordered from a vendor to the facility after arrival and to condition them to being handled by the experimenter. ...

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In contrast to CCI and FPI models inducing either focal or combination of focal and diffuse injury, the model of repetitive diffuse TBI described in this protocol allows for the induction of diffuse injury in the absence of focal brain injury and does not require scalp or cranial openings and the associated inflammation. An added benefit of the absence of craniectomy in this model is that it allows to not only implant the electrodes for chronic continuous EEG recording, but also the creation of a thinned-skull cranial wi...

Every year TBI affects an estimated 60 million people worldwide. Impacted individuals are at higher risk of developing epilepsy, which can manifest years after the initial injury. Though severe TBIs are associated with a higher risk of epilepsy, even mild TBI increases an individual&rsquo;s chance of developing epilepsy1,2,3,4. All TBIs can be classified as focal, diffuse, or a combination of both. Diffuse brain injury, present in many if not all TBIs, is a result of brain tissues of different densities shearing against each other due to acceleration-deceleration and rotational forces. By definition, diffuse injury only occurs in isolation in mild/concussive non-penetrating brain injury, in which no brain lesions are visible on computed tomography scans5.
There are currently two critical problems in the management of patients who have, or are at risk of, developing post-traumatic epilepsy (PTE). The first is that once PTE has manifested, seizures are resistant to available anti-epileptic drugs (AEDs)6. Secondly, AEDs are equally ineffective at preventing epileptogenesis, and there are no effective alternative therapeutic approaches. In order to address this deficit and find better therapeutic targets and candidates for treatment, it will be necessary to explore new cellular and molecular mechanisms at the root of PTE6.
One of the prominent features of post-traumatic epilepsy is the latent period between the initial traumatic event and the onset of spontaneous, unprovoked, recurrent seizures. The events that occur within this temporal window are a natural focus for researchers, because this time window might allow treatment and prevention of PTE altogether. Animal models are most commonly used for this research because they offer several distinct benefits, not the least of which is that continuous monitoring of human patients would be both impractical and costly over such potentially long spans of time. Additionally, cellular and molecular mechanisms at the root of epileptogenesis can only be explored in animal models.
Animal models with spontaneous post-traumatic seizures and epilepsy are preferred over models where seizures are induced after TBI by less physiologically relevant means, such as by chemoconvulsants or electric stimulation acutely, chronically, or by kindling. Spontaneous post-traumatic seizure models test how TBI modifies the healthy brain network leading to epileptogenesis. Studies using additional stimulation after TBI assess how exposure to TBI reduces seizure threshold and affects susceptibility to seizures. The advantages of animal models with seizures induced chemically or with electric stimulation are in testing the specific mechanisms of refractoriness to AEDs and the efficacy of existing and novel AEDs. Yet, the degree of relevance and translation of these data to humans may be ambiguous7 due to the following: 1) seizure mechanisms may be different from those induced by TBI alone; 2) not all of these models lead to spontaneous seizures7; 3) lesions created by the convulsant agent itself, with the cannula required for its delivery, or by stimulating electrode placement in depth structures (e.g., the hippocampus or amygdala) can already cause increased seizure susceptibility and even hippocampal epileptiform field potentials7. Furthermore, some convulsant agents (i.e., kainic acid) produce direct hippocampal lesions and sclerosis, which is not typical after diffuse TBI.
Until recently, only two animal models of post-traumatic epilepsy existed: controlled cortical impact (CCI, focal) or fluid percussion injury (FPI, focal and diffuse)8. Both models result in large focal lesions alongside tissue loss, hemorrhage, and gliosis in rodents8. These models mimic post-traumatic epilepsy induced by large focal lesions. A recent study demonstrated that repeated (3x) diffuse TBI is sufficient for the development of spontaneous seizures and epilepsy in mice even in the absence of focal lesions9, adding a third rodent PTE model with confirmed spontaneous recurrent seizures. This new model mimics cellular and molecular changes induced by diffuse TBI, better representing the human population with mild, concussive TBIs. In this model, the latent period of three weeks or more before seizure onset and the emergence of late, spontaneous, recurrent seizures allows for investigating the root causes of post-traumatic epileptogenesis, testing the efficacy of preventive approaches and new therapeutic candidates after seizure onset, and has potential for the development of biomarkers of post-traumatic epileptogenesis because approximately half of the animals develop post-traumatic epilepsy.
The choice of animal model for the study of post-traumatic epilepsy depends on the scientific question, the type of brain injury investigated, and what tools will be used to determine the underlying cellular and molecular mechanisms. Ultimately, any model of post-traumatic epilepsy must demonstrate both the emergence of spontaneous seizures after TBI and an initial latency period in a subset of TBI animals, because not all patients who incur a TBI go on to develop epilepsy. To do this, electroencephalography (EEG) with simultaneous video acquisition is used in this protocol. Understanding the technical aspects behind data acquisition hardware and approaches is critical for accurate data interpretation. The critical hardware aspects include the type of recording system, type of electrodes (screw or wire lead) and material they are made of, synchronized video acquisition (as part of the EEG system or third party), and properties of the computer system. It is imperative to set the appropriate acquisition parameters in any type of system depending on study goal, EEG events of interest, further analysis method, and sustainability of data storage. Lastly, the method of electrode configuration (montage) must be considered, as each has advantages and disadvantages and will affect the data interpretation.
This protocol details how to use the modified Marmarou weight drop model10,11 to induce diffuse injury resulting in spontaneous, unprovoked, recurrent seizures in mice, describes surgical approaches to acquire a single- and multi-channel continuous, and synchronized video EEG using monopolar, bipolar, or mixed montage.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.10&#34; screw</td>
			<td>Pinnacle Technology Inc., KS, USA</td>
			<td>8209</td>
			<td>0.10 inch long stainless steel</td>
		</tr>
		<tr>
			<td>0.10&#34; screw</td>
			<td>Pinnacle Technology Inc., KS, USA</td>
			<td>8403</td>
			<td>0.10 inch long with pre-soldered wire lead</td>
		</tr>
		<tr>
			<td>0.12&#34; screw</td>
			<td>Pinnacle Technology Inc., KS, USA</td>
			<td>8212</td>
			<td>0.12 inch long stainless steel</td>
		</tr>
		<tr>
			<td>1EEG headmount</td>
			<td>Invitro1 (subsidiary of Plastics One), VA, USA</td>
			<td>MS333/8-A/SPC</td>
			<td>3 individually Teflon-insulated platinum iridium wire electrodes (twisted or untwisted, 0.005 inch diameter) extending below threaded plastic pedestal</td>
		</tr>
		<tr>
			<td>2EEG/1EMG headmount</td>
			<td>Pinnacle Technology Inc., KS, USA</td>
			<td>8201</td>
			<td>2EEG/1EMG channels</td>
		</tr>
		<tr>
			<td>3% hydrogen peroxide</td>
			<td></td>
			<td></td>
			<td>Pharmacy</td>
		</tr>
		<tr>
			<td>3EEG headmount</td>
			<td>Pinnacle Technology Inc., KS, USA</td>
			<td>8235-SM-C</td>
			<td>custom 6-Pin Connector for 3EEG channels</td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td>Par Pharmaceuticals, Cos. Inc., Spring Valley, NY, USA</td>
			<td>060969</td>
			<td></td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td>Par Pharmaceuticals, Cos. Inc., Spring Valley, NY, USA</td>
			<td>060969</td>
			<td></td>
		</tr>
		<tr>
			<td>C57BL/6 mice</td>
			<td>Harlan/Envigo Laboratories Inc</td>
			<td></td>
			<td>male, 12-16 weeks old</td>
		</tr>
		<tr>
			<td>C57BL/6 mice</td>
			<td>The Jackson Laboratory</td>
			<td></td>
			<td>male, 12-16 weeks old</td>
		</tr>
		<tr>
			<td>Carprofen</td>
			<td>Zoetis Services LLC, Parsippany, NJ, USA</td>
			<td>026357</td>
			<td>NOTE: this drug is added during weight drop only if stereotactic electrode implantation will be performed on the same day</td>
		</tr>
		<tr>
			<td>Chlorhexidine antiseptic</td>
			<td></td>
			<td></td>
			<td>Pharmacy</td>
		</tr>
		<tr>
			<td>Dental cement and solvent kit</td>
			<td>Stoelting Co., USA</td>
			<td>51459</td>
			<td></td>
		</tr>
		<tr>
			<td>Drill</td>
			<td>Foredom</td>
			<td>HP4-917</td>
			<td></td>
		</tr>
		<tr>
			<td>Drill bit</td>
			<td>Meisinger USA, LLC, USA</td>
			<td>HM1-005-HP</td>
			<td>0.5 mm, Round, 1/4, Steel</td>
		</tr>
		<tr>
			<td>Dry sterilizer</td>
			<td>Cellpoint Scientific, USA</td>
			<td></td>
			<td>Germinator 500</td>
		</tr>
		<tr>
			<td>EEG System 1</td>
			<td>Biopac Systems, CA, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>EEG System 2</td>
			<td>Pinnacle Technology Inc., KS, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol &#8805;70%</td>
			<td>VWR, USA</td>
			<td>71001-652</td>
			<td>KOPTEC USP, Biotechnology Grade (140 Proof)</td>
		</tr>
		<tr>
			<td>Eye ointment</td>
			<td>Pro Labs Ltd, USA</td>
			<td></td>
			<td>Puralube Vet Ointment Sterile Ocular Lubricant available in general online stores and pharmacies</td>
		</tr>
		<tr>
			<td>Fluriso liquid for inhalation anesthesia</td>
			<td>MWI Veterinary Supply Co., USA</td>
			<td>502017</td>
			<td></td>
		</tr>
		<tr>
			<td>Hair removal product</td>
			<td>Church &#38; Dwight Co., Inc., USA</td>
			<td></td>
			<td>Nair cream</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>MWI Veterinary Supply Co., USA</td>
			<td>502017</td>
			<td></td>
		</tr>
		<tr>
			<td>Povidone-iodine surgical solution</td>
			<td>Purdue Products, USA</td>
			<td>004677</td>
			<td>Betadine</td>
		</tr>
		<tr>
			<td>Rimadyl/Carprofen</td>
			<td>Zoetis Services LLC, Parsippany, NJ, USA</td>
			<td>026357</td>
			<td></td>
		</tr>
		<tr>
			<td>Solder</td>
			<td></td>
			<td></td>
			<td>Harware store</td>
		</tr>
		<tr>
			<td>Soldering iron</td>
			<td>Weller, USA</td>
			<td>WP35</td>
			<td>ST7 tip, 0.8mm</td>
		</tr>
		<tr>
			<td>Stainless steel disc</td>
			<td></td>
			<td></td>
			<td>Custom made</td>
		</tr>
		<tr>
			<td>Sterile cotton swabs</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile gauze pads</td>
			<td>Fisher Scientific, USA</td>
			<td>22362178</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile poly-lined absorbent towels pads</td>
			<td>Cardinal Health, USA</td>
			<td>3520</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue adhesive</td>
			<td>3M Animal Care Products, USA</td>
			<td>1469SB</td>
			<td></td>
		</tr>
	</tbody>
</table>

inducing post-traumatic epilepsy in a mouse model of repetitive diffuse traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of acquired epilepsy. TBI can result in a focal or diffuse brain injury. Focal injury is a result of direct mechanical forces, sometimes penetrating through the cranium, creating a direct lesion in the brain tissue. These are visible during brain imaging as areas with contusion, laceration, and hemorrhage. Focal lesions induce neuronal death and glial scar formation and are present in 20%&minus;25% of all people who incur a TBI. However, in the majority of TBI cases, injury is caused by acceleration-deceleration forces and subsequent tissue shearing, resulting in nonfocal, diffuse damage. A subpopulation of TBI patients continues to develop post-traumatic epilepsy (PTE) after a latency period of months or years. Currently, it is impossible to predict which patients will develop PTE, and seizures in PTE patients are challenging to control, necessitating further research. Until recently, the field was limited to only two animal/rodent models with validated spontaneous post-traumatic seizures, both presenting with large focal lesions with massive tissue loss in the cortex and sometimes subcortical structures. In contrast to these approaches, it was determined that diffuse TBI induced using a modified weight drop model is sufficient to initiate development of spontaneous convulsive and non-convulsive seizures, even in the absence of focal lesions or tissue loss. Similar to human patients with acquired post-traumatic epilepsy, this model presents with a latency period after injury before seizure onset. In this protocol, the community will be provided with a new model of post-traumatic epilepsy, detailing how to induce diffuse non-lesional TBI followed by continuous long-term video-electroencephalographic animal monitoring over the course of several months. This protocol will detail animal handling, the weight drop procedure, the electrode placement for two acquisition systems, and the frequent challenges encountered during each of the steps of surgery, postoperative monitoring, and data acquisition.

The protocol outlined here describes the method for induction of a diffuse injury in isolation (e.g., in the absence a focal lesion) using a mouse model of repetitive diffuse TBI (Figure 1). Figure 1A depicts the weight drop device and its components (Figure 1A, a1&#8722;a5) used for induction of TBI in this model and crucial steps during the procedure (Figure 1...

Watch this Scientific Journal Video about Inducing Post-Traumatic Epilepsy in a Mouse Model of Repetitive Diffuse Traumatic Brain Injury at JoVE.com

Inducing Post-Traumatic Epilepsy in a Mouse Model of Repetitive Diffuse Traumatic Brain Injury

This systematic protocol describes a new animal model of post-traumatic epilepsy after repetitive mild traumatic brain injury. The first part details steps for traumatic brain injury induction using a modified weight drop model. The second part provides instructions on the surgical approach for single- and multi-channel electroencephalographic data acquisition systems.

Traumatic brain injury (TBI) is a leading cause of acquired epilepsy. TBI can result in a focal or diffuse brain injury. Focal injury is a result of ...

Our protocol is the first to detail a mouse model of post-traumatic epilepsy induced by mild traumatic brain injury. The use of a mild diffused traumatic brain injury model mimics an important aspect of the pathology of human traumatic brain injury which almost always has a diffused component. In order to develop biomarkers and treatments, research using models that appropriately reproduce aspects of human pathology is needed.Our traumatic brain injury model also has the potential to provide insight into the mechanisms that cause impairment of brain function after mild traumatic brain injury or concussion. After confirming a lack of response to pain reflex, place the mouse onto a foam pad and position the head of the mouse under the weight drop tube. Place a flat 1.3 centimeter diameter one millimeter thick 880 milligram weight stainless steel disc in the center of the animal's head between the eyes and the ears.Remove the pin in the weight drop tube to release the 100 gram weight rod from a height of 50 centimeters. To induce a sham injury in the control mice, remove the weight rod from the tube to prevent accidental release of the pin during weight drop. After weight drop induction, place the animal on its back on a heating pad covered with a sterile poly lined absorbent towel with monitoring until full recumbency.Then place the mouse in a clean cage that has been warmed on a heating pad with recovery gel and a few moistened chow pieces for 45 minutes. To prepare the surgical field for EEG electrode implantation, place a temperature sensor onto the pad and place the re-anesthetized brain injured mouse onto a sterile drape on top of the heating pad on the stereotactic apparatus. After fixing the head in place with ear bars, apply lubricating ointment to the animal's eyes and use depilatory cream to remove the hair from the scalp.Disinfect the exposed skin with three 20-second alternating swabs of povidone iodine surgical antiseptic solution and 70%ethanol in a circular motion. After removing the scalp, apply small hemostats on the opened skin borders to expand the exposed area. Next, use the scalpel to gently remove the periosteum and swab the cranium with hydrogen peroxide.When the cranium is cleared of tissue and exhibits a whitish appearance, dry the bone with a sterile gauze or swab. For electrode implantation, use a high-speed drill with a round 0.5 millimeter steel bit at 5, 000 to 6, 000 rotations per minute to create six burr holes for the screw electrodes. When all of the holes have been drilled, place the six screw electrodes into the burr holes and mix a half scoop of dental cement powder with several drops of solvent.Use a spatula to stir until the dental cement mixture is tacky but malleable and stiff enough to be properly condensed when placed on the animal's cranium. Apply the cement over the entire exposed surface of the cranium and each screw electrode. After one to two minutes, turn on the soldering iron and place the three EEG head mount into a stereotactic holder arm.Position the head mount over the skull so that the six wire lead positions match the position of the wire lead of each screw electrode. Lower the device so that its ventral part rests on top of the dental cement. Twist the wire of each lead from each of the screw electrodes with the corresponding wire lead of the head mount, solder each twisted pair of wire for proper signal conduction and use scissors to trim any excess wire.Bend each soldered pair of wire leads around the head mount. When all of the pairs have been bent, cover all of the wire with fresh dental cement leaving only the black portion of the head mount exposed. Release the hemostats holding the skin flaps and apply chlorhexidine antiseptic to the area around the implant to avoid infection.Then transfer the animal from the apparatus to a balance to measure the animal's weight as a reference for future monitoring before placing the animal in a clean cage on a warm heating pad with monitoring, recovery gel, and a few moistened chow pieces. In this figure, a spontaneous seizure in a mouse 97 days after repeated weight drop traumatic brain injury recorded using a three EEG head mount configured as demonstrated in this video protocol is shown. Here, a spontaneous non-convulsive electrographic seizure recorded in a mouse 65 days after repeated weight drop traumatic brain injury is shown.In this figure, a spontaneous seizure in a mouse 23 days after repeated weight drop traumatic brain injury was recorded using a one EEG head mount. The spectral power of a typical seizure indicates the highest density to be in the range of 10 to 40 hertz with a peak at 15 hertz. This protocol demonstrates the timelines for seizure onset in animals after repetitive weight drop traumatic brain injury demonstrating the incidence of seizure clustering in some animals and emphasizing the importance of acquiring continuous rather than intermittent recordings.Proper placement of the steel disc, careful implantation of the screw electrodes and careful soldering of the wire leads are all crucial for a successful long-term experiment. After EEG monitoring, animals with brain injury that develop seizures can be stratified from those that do not for subsequent analysis of their cellular, molecular, and physiological differences. To stratify animals with post-traumatic epilepsy from those that incur traumatic brain injury but do not develop seizures is critical for the development of interventions and biomarkers.

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Research

JoVE Journal

Behavior

Compensatory Limb Use and Behavioral Assessment of Motor Skill Learning Following Sensorimotor Cortex Injury in a Mouse Model of Ischemic Stroke

Mouse models have become increasingly popular in the field of behavioral neuroscience, and specifically in studies of experimental stroke. As models advance, it is important to develop sensitive behavioral measures specific to the mouse. The present protocol describes a skilled motor task for use in mouse models of stroke. The Pasta Matrix Reaching Task functions as a versatile and sensitive behavioral assay that permits experimenters to collect accurate outcome data and manipulate limb use to mimic human clinical phenomena including compensatory strategies (i.e., learned non-use) and focused rehabilitative training. When combined with neuroanatomical tools, this task also permits researchers to explore the mechanisms that support behavioral recovery of function (or lack thereof) following stroke. The task is both simple and affordable to set up and conduct, offering a variety of training and testing options for numerous research questions concerning functional outcome following injury. Though the task has been applied to mouse models of stroke, it may also be beneficial in studies of functional outcome in other upper extremity injury models.

Mouse models have become increasingly popular in studies of behavioral neuroscience. As models advance, it is important to develop sensitive behavioral measures specific to the mouse. This protocol describes the Pasta Matrix Reaching Task, which is a skilled motor task for use in mouse models of stroke.

Mouse models have become increasingly popular in the field of behavioral neuroscience, and specifically in studies of experimental stroke. As models ...

The Modified Hole Board - Measuring Behavior, Cognition and Social Interaction in Mice and Rats

This protocol describes the modified hole board (mHB), which combines features from a traditional hole board and open field and is designed to measure multiple dimensions of unconditioned behavior in small laboratory mammals (e.g., mice, rats, tree shrews and small primates). This paradigm is a valuable alternative for the use of a behavioral test battery, since a broad behavioral spectrum of an animal&#8217;s behavioral profile can be investigated in one single test.
The apparatus consists of a box, representing the &#8216;protected&#8217; area, separated from a group compartment. A board, on which small cylinders are staggered in three lines, is placed in the center of the box, representing the &#8216;unprotected&#8217; area of the set-up. The cognitive abilities of the animals can be measured by baiting some cylinders on the board and measuring the working and reference memory. Other unconditioned behavior, such as activity-related-, anxiety-related- and social behavior, can be observed using this paradigm. Behavioral flexibility and the ability to habituate to a novel environment can additionally be observed by subjecting the animals to multiple trials in the mHB, revealing insight into the animals&#8217; adaptive capacities.
Due to testing order effects in a behavioral test battery, na&#239;ve animals should be used for each individual experiment. By testing multiple behavioral dimensions in a single paradigm and thereby circumventing this issue, the number of experimental animals used is reduced. Furthermore, by avoiding social isolation during testing and without the need to food deprive the animals, the mHB represents a behavioral test system, inducing if any, very low amount of stress.

This protocol describes the modified hole board, which is a behavioral test set-up that comprises the characteristics of an open field and a traditional hole board. This set-up enables the differential analysis of unconditioned behavior of small laboratory mammals as well as the analysis of cognitive abilities.

This protocol describes the modified hole board (mHB), which combines features from a traditional hole board and open field and is designed to measure ...

Exploring the Use of Isolated Expressions and Film Clips to Evaluate Emotion Recognition by People with Traumatic Brain Injury

The current study presented 60 people with traumatic brain injury (TBI) and 60 controls with isolated facial emotion expressions, isolated vocal emotion expressions, and multimodal (i.e., film clips) stimuli that included contextual cues. All stimuli were presented via computer. Participants were required to indicate how the person in each stimulus was feeling using a forced-choice format. Additionally, for the film clips, participants had to indicate how they felt in response to the stimulus, and the level of intensity with which they experienced that emotion.

This paper describes how to implement a battery of behavioral tasks to examine emotion recognition of isolated facial and vocal emotion expressions, and a novel task using commercial television and film clips to assess multimodal emotion recognition that includes contextual cues.

The current study presented 60 people with traumatic brain injury (TBI) and 60 controls with isolated facial emotion expressions, isolated vocal emotion ...

Repetitive Transcranial Magnetic Stimulation to the Unilateral Hemisphere of Rat Brain

Previous rodent models of repetitive transcranial magnetic stimulation (rTMS) adopted whole-brain stimulation instead of unilateral hemispheric rTMS, which is unlike the protocols used for human subjects. We report a successful application of rTMS to the unilateral hemisphere of rat brain. The rTMS was delivered with a low-frequency (1 Hz), high-frequency (20 Hz), or sham stimulation protocol to one side of the brain by using a small 25-mm figure-8 coil. We placed the center of the coil 1 cm lateral to the vertex on the biauricular line and angulated the coil 45&#176; to the ground to minimize a potential direct effect of rTMS on the contralateral cortex. We also used an in-house water cooling system to enable repetitive magnetic stimulation for more than 20 min, even at a 20-Hz stimulation frequency. Increases in the transcriptions of immediate early genes (Arc, Junb, and Egr2) were greater after rTMS than after sham stimulation. After 5 consecutive days of 20-min 1-Hz rTMS, bdnf mRNA expression was significantly higher in stimulated cortex than in contralateral side. The model presented herein will elucidate the molecular mechanisms of rTMS by allowing analysis of the inter-hemispheric difference in its effect.

We applied repetitive transcranial magnetic stimulation (rTMS) to the unilateral hemisphere of rat brain, by placing a 25-mm figure-8 coil 1 cm lateral to the vertex on the biauricular line and angulating the coil by 45&#176;. An in-house water cooling system was used for rTMS for more than 20 min.

Previous rodent models of repetitive transcranial magnetic stimulation (rTMS) adopted whole-brain stimulation instead of unilateral hemispheric rTMS, ...

Wheel Running and Environmental Complexity as a Therapeutic Intervention in an Animal Model of FASD

Aerobic exercise (e.g., wheel running (WR) extensively used in animal research) positively impacts many measures of neuroplastic potential in the brain, such as rates of adult neurogenesis, angiogenesis, and expression of neurotrophic factors in rodents. This intervention has also been shown to mitigate behavioral and neuroanatomical aspects of the negative impacts of teratogens (i.e., developmental exposure to alcohol) and age-related neurodegeneration in rodents. Environmental complexity (EC) has been shown to produce numerous neuroplastic benefits in cortical and subcortical structures and can be coupled with wheel running to increase the proliferation and survival of new cells in the adult hippocampus. The combination of these two interventions provides a robust &#34;superintervention&#34; (WR-EC) that can be implemented in a range of rodent models of neurological disorders. We will discuss the implementation of WR/EC and its constituent interventions for use as a more powerful therapeutic intervention in rats using the animal model of prenatal exposure to alcohol in humans. We will also discuss which elements of the procedures are absolutely necessary for the interventions and which ones may be altered depending on the experimenter&#39;s question or facilities.

Cardiovascular exercise and stimulating experiences in a complex environment have positive benefits on multiple measures of neuroplasticity within the rodent brain. This article will discuss the implementation of these interventions as a &#34;superintervention&#34; which combines wheel running and environmental complexity and will address the limitations of these interventions.

Aerobic exercise (e.g., wheel running (WR) extensively used in animal research) positively impacts many measures of neuroplastic potential in the brain, ...

Assessing Spatial Memory Impairment in a Mouse Model of Traumatic Brain Injury Using a Radial Water Tread Maze

Despite the recent increase in use of mouse models in scientific research, researchers continue to use cognitive tasks that were originally designed and validated for rat use. The Radial Water Tread (RWT) maze test of spatial memory (designed specifically for mice and requiring no swimming) has been shown previously to successfully distinguish between controlled cortical impact-induced TBI mice and sham controls. Here, a detailed protocol for this task is presented. The RWT maze capitalizes on the natural tendency of mice to avoid open areas in favor of hugging the sides of an apparatus (thigmotaxis). The walls of the maze are lined with nine escape holes placed above the floor of the apparatus, and mice are trained to use visual cues to locate the escape hole that leads out of the maze. The maze is filled with an inch of cold water, sufficient to motivate escape but not deep enough to require that the mouse swim. The acquisition period takes only four training days, with a test of memory retention on day five and a long-term memory test on day 12. The results reported here suggest that the RWT maze is a feasible alternative to rat-validated, swimming-based cognitive tests in the assessment of spatial memory deficits in mouse models of TBI.

Here we present a protocol for a mouse-specific test of cognition that does not require swimming. This test can be used to successfully distinguish controlled cortical impact-induced traumatic brain injury mice from sham controls.

Despite the recent increase in use of mouse models in scientific research, researchers continue to use cognitive tasks that were originally designed and ...

Detecting Behavioral Deficits in Rats After Traumatic Brain Injury

With the increasing incidence of traumatic brain injury (TBI) in both civilian and military populations, TBI is now considered a chronic disease; however, few studies have investigated the long-term effects of injury in rodent models of TBI. Shown here are behavioral measures that are well-established in TBI research for times early after injury, such as two weeks, until two months. Some of these methods have previously been used at later times after injury, up to one year, but by very few laboratories. The methods demonstrated here are a short neurological assessment to test reflexes, a Beam-Balance to test balance, a Beam-Walk to test balance and motor coordination, and a working memory version of the Morris water maze that can be sensitive to deficits in reference memory. Male rats were handled and pre-trained to neurological, balance, and motor coordination tests prior to receiving parasagittal fluid percussion injury (FPI) or sham injury. Rats can be tested on the short neurological assessment (neuroscore), the beam-balance, and the Beam-Walk multiple times, while testing on the water maze can only be done once. This difference is because rats can remember the task, thus confounding the results if repeated testing is attempted in the same animal. When testing from one to three days after injury, significant differences are detected in all three non-cognitive tasks. However, differences in the Beam-Walk task were not detectable at later time points (after 3 months). Deficits were detected at 3 months in the Beam-Balance and at 6 months in the neuroscore. Deficits in working memory were detected out to 12 months after injury, and a deficit in a reference memory first appeared at 12 months. Thus, standard behavioral tests can be useful measures of persistent behavioral deficits after FPI.

The goal of the behavioral tests presented here is to detect functional deficits in rats after traumatic brain injury. Four specific tests are presented that detect deficits in behaviors to reflect the damage to specific brain areas at times extending to one year after injury.

With the increasing incidence of traumatic brain injury (TBI) in both civilian and military populations, TBI is now considered a chronic disease; however, ...

Using Laser Doppler Imaging and Monitoring to Analyze Spinal Cord Microcirculation in Rat

Laser Doppler flowmetry (LDF) is a noninvasive method for blood flow (BF) measurement, which makes it preferable for measuring microcirculatory alterations of the spinal cord. In this article, our goal was to use both Laser Doppler imaging and monitoring to analyze the change of BF after spinal cord injury. Both the laser Doppler image scanner and the probe/monitor were being employed to obtain each readout. The data of LDPI provided a local distribution of BF, which gave an overview of perfusion around the injury site and made it accessible for comparative analysis of BF among different locations. By intensely measuring the probing area over a period of time, a combined probe was used to simultaneously measure the BF and oxygen saturation of the spinal cord, showing overall spinal cord perfusion and oxygen supply. LDF itself has a few limitations, such as relative flux, sensitivity to movement, and biological zero signal. However, the technology has been applied in clinical and experimental study due to its simple setup and rapid measurement of BF.

Here we present a combination of laser Doppler perfusion imaging (LDPI) and laser Doppler perfusion monitoring (LDPM) to measure spinal cord local blood flows and oxygen saturation (SO2), as well as a standardized procedure for introducing spinal cord trauma on rat.

Laser Doppler flowmetry (LDF) is a noninvasive method for blood flow (BF) measurement, which makes it preferable for measuring microcirculatory ...

A New Method for Inducing a Depression-Like Behavior in Rats

Contagious depression is a phenomenon that is yet to be fully recognized and this stems from insufficient material on the subject. At the moment, there is no existing format for studying the mechanism of action, prevention, containment, and treatment of contagious depression. The purpose of this study, therefore, was to establish the first animal model of contagious depression.
Healthy rats can contract depressive behaviors if exposed to depressed rats. Depression is induced in rats by subjecting them to several manipulations of chronic unpredictable stress (CUS) over 5 weeks, as described in the protocol. A successful sucrose preference test confirmed the development of depression in the rats. The CUS-exposed rats were then caged with na&#239;ve rats from the contagion group (1 na&#239;ve rat/2 depressed rats in a cage) for an additional 5 weeks. 30 social groups were created from the combination of CUS-exposed rats and na&#239;ve rats.
This proposed depression-contagion protocol in animals consists mainly of cohabiting CUS-exposed and healthy rats for 5 weeks. To ensure that this method works, a series of tests are carried out - first, the sucrose preference test upon inducing depression to rats, then, the sucrose preference test, alongside the open field and forced-swim tests at the end of the cohabitation period. Throughout the experiment, rats are given tags and are always returned to their cages after each test.
A few limitations to this method are the weak differences recorded between the experimental and control groups in the sucrose preference test and the irreversible traumatic outcome of the forced swim test. These may be worth considering for suitability before any future application of the protocol. Nonetheless, following the experiment, na&#239;ve rats developed contagion depression after 5 weeks of sharing the same cage with the CUS-exposed rats.

This protocol describes a new model by which healthy rats could contract depression over a given time periodthrough contagion by exposure to chronic unpredictable stressed (CUS) rats.

Contagious depression is a phenomenon that is yet to be fully recognized and this stems from insufficient material on the subject. At the moment, there is ...

Stress-Enhanced Fear Learning, a Robust Rodent Model of Post-Traumatic Stress Disorder

Fear behaviors are important for survival, but disproportionately high levels of fear can increase the vulnerability for developing psychiatric disorders such as post-traumatic stress disorder (PTSD). To understand the biological mechanisms of fear dysregulation in PTSD, it is important to start with a valid animal model of the disorder. This protocol describes the methodology required to conduct stress-enhanced fear learning (SEFL) experiments, a preclinical model of PTSD, in both rats and mice. SEFL was developed to recapitulate critical aspects of PTSD, including long-term sensitization of fear learning caused by an acute stressor. SEFL uses aspects of Pavlovian fear conditioning but produces a distinct and robust sensitized fear response far greater than normal conditional fear responses. The trauma procedure involves placing a rodent in a conditioning chamber and administering 15 unsignaled shocks randomly distributed over 90 minutes (for rat experiments; for mouse experiments, 10 unsignaled shocks randomly distributed over 60 minutes are used). On day 2, rodents are placed in a novel conditioning context where they receive a single shock; then, on day 3 they are placed back in the same context as on day 2 and tested for changes in freezing levels. Rodents that previously received the trauma display enhanced levels of freezing on the test day compared to those that received no shocks on the first day. Thus, with this model, a single highly stressful experience (the trauma) produces extreme fear of the stimuli associated with the traumatic event.

Here we describe the detailed methodology required to conduct stress-enhanced fear learning (SEFL) experiments, a preclinical model of post-traumatic stress disorder, in both rats and mice. The model utilizes aspects of Pavlovian fear conditioning and freezing as an index of enhanced fear in rodents.

Fear behaviors are important for survival, but disproportionately high levels of fear can increase the vulnerability for developing psychiatric disorders ...