The work done are part of Dmitry Frank&#39;s PhD thesis.

The experiments were approved by the Animal Care Committee of the Ben-Gurion University of the Negev.The experiments were performed following the recommendations of the Declarations of Helsinki and Tokyo and the Guidelines for the Care and Use of Laboratory Animals of the European Community. Adult male Sprague-Dawley rats, weighing 300-350 g, were used in the present study. The animals were housed at a room temperature of 22 &#176;C &#177; 1 &#176;C and a humidity of 40%-60% with light-dark cycles.
1. Animal preparation
<ol>
	<li>Select at random 30 adult male rats, and divide them into two groups: TBI and sham.</li>
	<li>Provide chow (see the Table of Materials) and water ad libitum. 
	NOTE: Perform all the steps of the test at the same time to control for the effect of time of day on behavioral performance. It is best to conduct the behavior tests in the morning (between 6:00 a.m. and 12:00 p.m.) to avoid disturbance from general activity.</li>
	<li>Perform baseline assessments of the neurological severity score before injury in both groups of rats, as detailed in step 3 and Table 1.</li>
	<li>Anesthetize the rats with 4% (for induction) and 1.5% (for maintenance) isoflurane. Inject Buprenorphine (0.05-0.1 mg/kg; SC) for preemptive analgesia.</li>
	<li>Check for the immobilization of the rat by testing for a lack of movement or pedal reflex in response to a stimulant. 
	NOTE: For anesthesia administration, a continuous flow of isoflurane is recommended.</li>
</ol>
2. Surgical procedure
NOTE: All procedures are to be performed in aseptic conditions. Use sterile gloves. Change the gloves if any non-sterile surface is touched. Apply ophthalmic lubricant to both eyes to prevent drying. The parasagittal fluid-percussion injury was performed following previously published reports18,20.
<ol>
	<li>Infiltrate the scalp with 0.5% bupivacaine (see the Table of Materials), perform a 10 mm incision, and retract the tissues laterally.</li>
	<li>Perform craniotomy18,20 4 mm posterior and 4 mm lateral of bregma. 
	NOTE: The surgical area must be disinfected several times in a circular motion with both an iodine-based or chlorhexidine-based scrub and alcohol.&#160;</li>
	<li>Induce TBI18,19 by a fluid-percussion device (see the Table of Materials) over 21-23 ms through the three-way stopcock. 
	NOTE: Perform moderate TBI with an amplitude of 2.5 atm.</li>
	<li>Perform craniotomy on the group of sham-operated rats (Figure 1). Do not induce TBI for the sham-operated group.</li>
	<li>Perform 0.1% bupivacaine infiltration before closing the wound. Administer intramuscular buprenorphine (0.01-0.05 mg/kg) as postoperative analgesia before withdrawing the isoflurane. 
	NOTE: Repeat doses of buprenorphine every 12 h for at least 48 h.</li>
	<li>Transfer the rat to the recovery room, and monitor its respiratory (e.g., respiratory arrest), neurological (e.g., paralysis), and cardiovascular state (e.g., changes in the color of pupils, decreases in soft tissue perfusion, and bradycardia) for 24 h.</li>
</ol>
3. Neurological severity score evaluation
NOTE: The highest possible score for behavioral alterations and motor function is 24 points. A score of 0 represents intact neurological status, and a score of 24 represents severe neurological dysfunction21,22,23 (Table 1).
<ol>
	<li>Evaluate the neurological severity score (NSS) as previously described24 on the TBI and sham rats before surgery, at 48 h after surgery (Figure 2A), and on day 28 after surgery (Figure 2B).</li>
</ol>
4. Studying the dominant- submissive behavior
<ol>
	<li>Randomly divide the rats into cages 1 week before the test. 
	NOTE: Each cage should contain one sham-operated rat and one TBI rat.</li>
	<li>Perform one 15 min session every day for 2 days before testing so that rats can acclimate to the protocol. 
	NOTE: The dominant-submissive task was initiated on day 29 after injury (Figure 1).</li>
	<li>Use an apparatus (see the Table of Materials) made from two transparent acrylic glass boxes (30 cm x 20 cm x 20 cm, Box A and Box B, Figure 3) connected by a slender 15 cm x 15 cm x 60 cm tunnel15,19,25.</li>
	<li>Fill a feeder (Figure 3) with sweetened milk, and place it at the tunnel&#39;s center. Use milk consisting of 10% sugar and 3% fat.</li>
	<li>Place the apparatus on a table with a height of 80 cm above the floor.</li>
	<li>Place each rat in the apparatus for 15 min for habituation on the first 2 days. Start the task after 2 habituation days.</li>
	<li>Randomly select one rat from the control group and one from the traumatic brain injury (TBI) group, and set them at equal distances from the feeder, allowing them to explore for 5 min.</li>
	<li>Allow the rats access to water ad libitum. 
	NOTE: The task lasted for 5 days. Food restriction was performed for the entire task period. The food was given every day for 1 h after the test period.</li>
	<li>Clean the equipment with 5% alcohol before performing the subsequent tests with other rats. 
	&#8203;NOTE: Cleaning the apparatus will eliminate the smell of the previous rats. Perform the test in a room with proper air circulation.</li>
</ol>
5. Recording the video and data analysis
<ol>
	<li>Position a camera, and install the recommended computer software (see the Table of Materials) to capture, save, and process the data. 
	NOTE: The camera needs to be installed at a height of 290 cm from the floor.</li>
	<li>Record the video while the rats are in the arena. 
	NOTE: The camera and the apparatus were positioned 210 cm apart. The part of the arena where the test is conducted must be visible in the camera frame.</li>
	<li>Perform data analysis23 manually by two analysts blinded to the groups.</li>
</ol>

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</ol>

The authors have nothing to disclose.

Clinical studies indicate that brain injury may increase the risk of psychiatric disorders26,27. Moreover, TBI affects the development of social behavior28,29. In this protocol, the TBI model had an effect on the presentation of dominant-submissive behavior. Dominant-submissive behavior manifested itself in terms of time spent on the feeder and who came first to the feeder.
In ...

Intraspecies competition occurs when members of the same species compete for a limited resource at the same time1. In contrast, interspecies competition occurs between members of two different species2. Intraspecies competition is divided into two types, including interference (adapted) and exploitation (contest), and arises depending on the type of resource in contention, such as food and territory3.
The existence of social hierarchies is impossible without dominant-submissive relationships (DSRs). Dominance presents as &#34;winning&#34; and subordination as &#34;losing&#34; within pairs of animals4. However, DSRs appear not only in pairs but also in groups of three or more. In 1922, Thorleif Schjelderup-Ebbe described the dominance hierarchy in domestic chickens. The principal distinguishing signs between the dominant and subordinate animals were time spent at the feeder and aggressive behavior. The dominance hierarchy is divided into two forms: linear and nonlinear5. Linear dominance involves two groups, A and B. In this paradigm of transitive relationships6, group A dominates group B, or group B dominates group A. Nonlinear dominance occurs when there is at least one circular relationship: A dominates B, B dominates C, and C dominates A7.
Models for assessing dominant-submissive behavior exist for different species, including rodents, birds8, non-human primates9,10,11, and humans12. The dominant-submissive method is well represented in the literature and has been applied as a model to assess mania and depression13, as well as antidepressant drug activity14. This model has been used to investigate early life stress after maternal separation in adult rats15. The DSR paradigms can be divided into three models: the reduction of dominant behavior model13,16, the reduction of submissive behavior model14, and the clonidine-reversal of dominance model17.
This study demonstrates an investigation of DSR through tasks based on food competition. The advantages of this method are its easy reproducibility and the ability to observe and accurately analyze dominant-submissive behavior. In addition, the dominant-submissive behavioral task relies on food rather than territory, unlike comparable behavioral tasks, which makes this behavioral task lower cost and simpler and researchers do not need to undergo complicated training to perform the task and process the data.
The overall goal of the current study is to demonstrate the development of DSR after traumatic brain injury (TBI). TBI is associated with social impairments, depression, and anxiety. The model of inducing TBI is a simple and effective standard model that involves inducing traumatic brain injury with a fluid percussion device18,19.

<table><tbody><tr><td>2% chlorhexidine in 70% alcohol solution</td><td>SIGMA - ALDRICH</td><td>500 cc</td><td>For general antisepsis of the skin in the operatory field</td></tr><tr><td>4 boards of different thicknesses (1.5 cm, 2.5 cm, 5 cm and 8.5 cm)</td><td>This is to evaluate neurological defect</td><td></td><td></td></tr><tr><td>4-0 Nylon suture</td><td>4-00</td><td></td><td></td></tr><tr><td>Bottles</td><td>Techniplast</td><td>ACBT0262SU</td><td></td></tr><tr><td>Bupivacaine 0.1 %</td><td></td><td></td><td></td></tr><tr><td>Diamond Hole Saw Drill 3 mm diameter</td><td>Glass Hole Saw Kit</td><td></td><td>Optional.</td></tr><tr><td>Digital Weighing Scale</td><td>SIGMA - ALDRICH</td><td>Rs 4,000</td><td></td></tr><tr><td>Dissecting scissors</td><td>SIGMA - ALDRICH</td><td>Z265969</td><td></td></tr><tr><td>Ethanol 99.9 %</td><td>Pharmacy</td><td></td><td>5%-10% solution used to clean equipment and remove odors</td></tr><tr><td>Fluid-percussion device</td><td>custom-made at the university workshop</td><td></td><td>No specific brand is recommended.</td></tr><tr><td>Gauze Sponges</td><td>Fisher</td><td></td><td></td></tr><tr><td>Gloves (thin laboratory gloves)</td><td></td><td></td><td>Optional.</td></tr><tr><td>Heater with thermometer</td><td>Heatingpad-1</td><td>Model: HEATINGPAD-1/2</td><td>No specific brand is recommended.</td></tr><tr><td>Horizon-XL</td><td>Mennen Medical Ltd</td><td></td><td></td></tr><tr><td>Isofluran, USP 100%</td><td>Piramamal Critical Care, Inc</td><td>NDC 66794-017</td><td>Anesthetic liquid for inhalation</td></tr><tr><td>Logitech Webcam Software</td><td>Logitech</td><td>2.51</td><td>Software for video camera</td></tr><tr><td>Operating forceps</td><td>SIGMA - ALDRICH</td><td></td><td></td></tr><tr><td>Operating Scissors</td><td>SIGMA - ALDRICH</td><td></td><td></td></tr><tr><td>PC Computer for USV recording and data analyses</td><td>Intel</td><td></td><td>Intel core i5-6500 CPU @ 3.2GHz, 16 GB RAM, 64-bit operating system</td></tr><tr><td>Plexiglass boxes linked by a narrow passage</td><td></td><td></td><td>Two transparent 30 cm &amp;times; 20 cm &amp;times; 20 cm plexiglass boxes linked by a narrow 15 cm &amp;times; 15 cm &amp;times; 60 cm passage</td></tr><tr><td>Purina Chow</td><td>Purina</td><td>5001</td><td>Rodent laboratory chow given to rats,&amp;nbsp; is a lifecycle nutrition that has been used in biomedical research</td></tr><tr><td>Rat cages (rat home cage or another enclosure)</td><td>Techniplast</td><td>2000P</td><td>No specific brand is recommended</td></tr><tr><td>Scalpel blades 11</td><td>SIGMA - ALDRICH</td><td>S2771</td><td></td></tr><tr><td>SPSS</td><td>SPSS Inc., Chicago, IL, USA</td><td>A 20 package</td><td></td></tr><tr><td>Stereotaxic Instrument</td><td>custom-made at the university workshop</td><td></td><td>No specific brand is recommended</td></tr><tr><td>Timing device</td><td>Interval Timer:Timing for recording USV&#039;s</td><td></td><td>Optional. Any timer will do, although it is convenient to use an interval timer if you are tickling multiple rats</td></tr><tr><td>Video camera</td><td>Logitech</td><td>C920 HD PRO WEBCAM</td><td>Digital video camera for high definition recording of rat behavior under dominant submissive test</td></tr></tbody></table>

assessing dominant-submissive behavior in adult rats following traumatic brain injury

Competition over resources such as food, territory, and mates significantly influences relationships within animal species and is mediated through social hierarchies that are often based on dominant-submissive relationships. The dominant-submissive relationship is a normal behavioral pattern among the individuals of a species. Traumatic brain injury is a frequent cause of social interaction impairment and the reorganization of dominant-submissive relationships in animal pairs. This protocol describes submissive behavior in adult male Sprague-Dawley rats after the induction of traumatic brain injury using a fluid-percussion model compared to naive rats through a series of dominant-submissive tests performed between 29 days and 33 days after induction. The dominant-submissive behavior test shows how brain injury can induce submissive behavior in animals competing for food. After traumatic brain injury, the rodents were more submissive, as indicated by them spending less time at the feeder and being less likely to arrive first at the trough compared to the control animals. According to this protocol, submissive behavior develops after traumatic brain injury in adult male rats.

Neurological severity score assessment 
Neurological deficits were assessed in male rats after TBI using the NSS. The rats were divided into two groups: one TBI group and one control group. The control group was subjected to sham surgery. The NSS allowed for the assessment of motor function and behavior alteration by a points system22,23; a score of 24 indicated a severe neurological dysfunction, and a score of 0 represented intact neurologi...

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Assessing Dominant-Submissive Behavior in Adult Rats Following Traumatic Brain Injury

The present protocol describes a rat model of fluid percussion-induced traumatic brain injury followed by a series of behavioral tests to understand the development of dominant and submissive behavior. Using this model of traumatic brain injury in conjunction with specific behavioral tests enables the study of social impairments following brain injury.

Competition over resources such as food, territory, and mates significantly influences relationships within animal species and is mediated through social ...

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Research

JoVE Journal

Behavior

1.4K Views.  Ben-Gurion University of the Negev. In deze studie willen we een onderzoek naar dominant-onderdanige relaties aantonen door middel van tests op basis van voedselconcurrentie. Het algemene doel van de huidige studie is om de ontwikkeling van dominant-onderdanige relatie na traumatisch hersenletsel aan te tonen. De voordelen van deze methode zijn de eenvoudige reproduceerbaarheid en het vermogen om dominant-onderdanig gedrag te observeren en nauwkeurig te analyseren.De dominant-onderdanige methode is goed vertegenwoordigd ...

Video: Assessing Dominant-Submissive Behavior in Adult Rats Following Traumatic Brain Injury

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, ...

Peering into the Dynamics of Social Interactions: Measuring Play Fighting in Rats

Play fighting in the rat involves attack and defense of the nape of the neck, which if contacted, is gently nuzzled with the snout. Because the movements of one animal are countered by the actions of its partner, play fighting is a complex, dynamic interaction. This dynamic complexity raises methodological problems about what to score for experimental studies. We present a scoring schema that is sensitive to the correlated nature of the actions performed. The frequency of play fighting can be measured by counting the number of playful nape attacks occurring per unit time. However, playful defense, as it can only occur in response to attack, is necessarily a contingent measure that is best measured as a percentage (#attacks defended/total # attacks X 100%). How a particular attack is defended against can involve one of several tactics, and these are contingent on defense having taken place; consequently, the type of defense is also best expressed contingently as a percentage. Two experiments illustrate how these measurements can be used to detect the effect of brain damage on play fighting even when there is no effect on overall playfulness. That is, the schema presented here is designed to detect and evaluate changes in the content of play following an experimental treatment.

Play fighting in the rat involves attack and defense of the nape of the neck, which if contacted, is gently nuzzled with the snout. Because the movements of one animal are countered by the actions of its partner, play fighting is a complex, dynamic interaction. This dynamic complexity raises methodological problems about what to score for experimental studies. We present a scoring schema that is sensitive to the correlated nature of the actions performed. Two experiments illustrate how these measurements can be used to detect the effect of brain damage on play fighting even when there is no effect on overall playfulness. That is, the schema presented here is designed to detect and evaluate changes in the content of play following an experimental treatment.

Play fighting in the rat involves attack and defense of the nape of the neck, which if contacted, is gently nuzzled with the snout. Because the movements ...

Neuroscience

A Novel Model of Mild Traumatic Brain Injury for Juvenile Rats

Despite growing evidence that childhood represents a major risk period for mild traumatic brain injury (mTBI) from sports-related concussions, motor vehicle accidents, and falls, a reliable animal model of mTBI had previously not been developed for this important aspect of development. The modified weight-drop technique employs a glancing impact to the head of a freely moving rodent transmitting acceleration, deceleration, and rotational forces upon the brain. When applied to juvenile rats, this modified weight-drop technique induced clinically relevant behavioural outcomes that were representative of post-concussion symptomology. The technique is a rapidly applied procedure with an extremely low mortality rate, rendering it ideal for high-throughput studies of therapeutics. In addition, because the procedure involves a mild injury to a closed head, it can easily be used for studies of repetitive brain injury. Owing to the simplistic nature of this technique, and the clinically relevant biomechanics of the injury pathophysiology, the modified weight-drop technique provides researchers with a reliable model of mTBI that can be used in a wide variety of behavioural, molecular, and genetic studies.

The modified weight-drop technique is an easy, cost-effective procedure used for the induction of mild traumatic brain injury in juvenile rats. This novel technique produces clinically relevant symptomology that will advance the study of mild traumatic brain injury (mTBI) and concussion.

Despite growing evidence that childhood represents a major risk period for mild traumatic brain injury (mTBI) from sports-related concussions, motor ...

Medicine

A Mouse Model of Single and Repetitive Mild Traumatic Brain Injury

Mild Traumatic Brain Injury (mTBI) can result in the acute loss of brain function, including a period of confusion, a loss of consciousness (LOC), focal neurological deficits and even amnesia. Athletes participating in contact sports are at high risk of exposure to large number of mTBIs. In terms of the level of injury in a sporting athlete, a mTBI is defined as a mild injury that does not cause gross pathological changes, but does cause short-term neurological deficits that are spontaneously resolved. Despite previous attempts to model mTBI in mice and rats, many have reported gross adverse effects including skull fractures, intracerebral bleeding, axonal injury and neuronal cell death. Herein, we describe our highly reproducible animal model of mTBI that reproduces clinically relevant symptoms. This model uses a custom made pneumatic impactor device to deliver a closed-head trauma. This impact is made under precise velocity and deformation parameters, creating a reliable and reproducible model to examine the mechanisms that contribute to effects of single or repetitive concussive mTBI.

Athletes absorb several hundred mild traumatic brain injuries (mTBI)/concussions every year; however, the consequence of these on the brain is poorly understood. Therefore, an animal model of single and repetitive mTBI that consistently replicates clinically relevant symptoms provides the means to advance the study of mTBI and concussion.

Mild Traumatic Brain Injury (mTBI) can result in the acute loss of brain function, including a period of confusion, a loss of consciousness (LOC), focal ...

Spinal Cord Lateral Hemisection and Asymmetric Behavioral Assessments in Adult Rats

Incomplete spinal cord injury (SCI) often leads to impairments of sensorimotor functions and is clinically the most frequent type of SCI. Human Brown-S&#233;quard syndrome&#160;is a common type of incomplete SCI caused by a lesion to one half of the spinal cord which results in paralysis and loss of&#160;proprioception&#160;on the same (or ipsilesional) side as the injury, and loss of pain and temperature sensation on the opposite (or contralesional) side. Adequate methodologies for producing a spinal cord lateral hemisection (HX) and assessing neurological impairments are essential to establish a reliable animal model of Brown-S&#233;quard syndrome. Although lateral hemisection model plays a pivotal role in basic and translational research, standardized protocols for creating such a hemisection and assessing unilateralized function are lacking. The goal of this study is to describe step-by-step procedures to produce a rat spinal lateral HX at the 9th thoracic (T9) vertebral level. We, then, describe a combined behavior scale for HX (CBS-HX) that provides a simple and sensitive assessment of asymmetric neurological performance for unilateral SCI. The CBS-HX, ranging from 0 to 18, is composed of 4 individual assessments which include unilateral hindlimb stepping (UHS), coupling, contact placing, and grid walking. For CBS-HX, the ipsilateral and contralateral hindlimbs are assessed separately. We found that, after a T9 HX, the ipsilateral hindlimb showed impaired behavior function whereas the contralateral hindlimb showed substantial recovery. The CBS-HX effectively discriminated behavioral functions between ipsilateral and contralateral hindlimbs and detected temporal progression of recovery of the ipsilateral hindlimb. The CBS-HX components can be analyzed separately or in combination with other measures when needed. Although we only provided visual descriptions of the surgical procedures and behavioral assessments of a thoracic HX, the principle may be applied to other incomplete SCIs and at other levels of the injury.

Here we describe surgical procedures to produce a reliable spinal cord lateral hemisection (HX) at the 9th thoracic level in adult rats and neurobehavioral assessments designed for detecting asymmetric deficits after such a unilateral injury.

Incomplete spinal cord injury (SCI) often leads to impairments of sensorimotor functions and is clinically the most frequent type of SCI. Human ...

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 ...

A Metric Test for Assessing Spatial Working Memory in Adult Rats Following Traumatic Brain Injury

Impairments to sensory, short-term, and long-term memory are common side effects after traumatic brain injury (TBI). Due to the ethical limitations of human studies, animal models provide suitable alternatives to test treatment methods, and to study the mechanisms and related complications of the condition. Experimental rodent models have historically been the most widely used due to their accessibility, low cost, reproducibility, and validated approaches. A metric test, which tests the ability to recall the placement of two objects at various distances and angles from one another, is a technique to study impairment in spatial working memory (SWM) after TBI. The significant advantages of metric tasks include the possibility of dynamic observation, low cost, reproducibility, relative ease of implementation, and low stress environment. Here, we present a metric test protocol to measure impairment of SWM in adult rats after TBI. This test provides a feasible way to evaluate physiology and pathophysiology of brain function more effectively.

Traumatic brain injury (TBI) is commonly associated with memory impairment. Here, we present a protocol to assess spatial working memory after TBI via a metric task. A metric test is a useful tool to study spatial working memory impairment after TBI.

Impairments to sensory, short-term, and long-term memory are common side effects after traumatic brain injury (TBI). Due to the ethical limitations of ...

Assessing Changes in Synaptic Plasticity Using an Awake Closed-Head Injury Model of Mild Traumatic Brain Injury

Mild traumatic brain injuries (mTBIs) are a prevalent health issue in North America. There is increasing pressure to utilize ecologically valid models of closed-head mTBI in the preclinical setting to increase translatability to the clinical population. The awake closed-headed injury (ACHI) model uses a modified controlled cortical impactor to deliver closed-headed injury, inducing clinically relevant behavioral deficits without the need for a craniotomy or the use of an anesthetic.
This technique does not normally induce fatalities, skull fractures, or brain bleeds, and is more consistent with being a mild injury. Indeed, the mild nature of the ACHI procedure makes it ideal for studies investigating repetitive mTBI (r-mTBI). Growing evidence indicates that r-mTBI can result in a cumulative injury that produces behavioral symptoms, neuropathological changes, and neurodegeneration. r-mTBI is common in youths playing sports, and these injuries occur during a period of robust synaptic reorganization and myelination, making the younger population particularly vulnerable to the long-term influences of r-mTBI.
Further, r-mTBI occurs in cases of intimate partner violence, a condition for which there are few objective screening measures. In these experiments, synaptic function was assessed in the hippocampus in juvenile rats that had experienced r-mTBI using the ACHI model. Following the injuries, a tissue slicer was utilized to make hippocampal slices to evaluate bidirectional synaptic plasticity in the hippocampus at either 1 or 7 days following the r-mTBI. Overall, the ACHI model provides researchers with an ecologically valid model to study changes in synaptic plasticity following mTBI and r-mTBI.

Here, it is demonstrated how an awake closed-head injury model can be used for examining the effects of repeated mild traumatic brain injury (r-mTBI) on synaptic plasticity in the hippocampus. The model replicates important features of r-mTBI in patients and is used in conjunction with in vitro electrophysiology.

Mild traumatic brain injuries (mTBIs) are a prevalent health issue in North America. There is increasing pressure to utilize ecologically valid models of ...

Validating Injury Response and Behavioral Assessments in an mTBI Rat Model

Rat Model of Closed-Head Mild Traumatic Injury and its Validation

Animal models are crucial for advancing our understanding of mild traumatic brain injury (mTBI) and guiding clinical research. To achieve meaningful insights, developing a stable and reproducible animal model is essential. In this study, we report a detailed description of a closed-head mTBI model and a representative validation method using Sprague-Dawley rats to verify the modeling effect. The model involves dropping a 550 g mass weight from a height of 100 cm directly onto the head of a rat on a destructible surface, followed by a 180-degree turn. To assess the injury, rats underwent a series of neurobehavioral assessments 10 min post-injury, including time of loss of consciousness, first seeking-behavior time, escape ability, and beam balance ability test. During the acute and subacute stages following the injury, behavioral tests were conducted to assess motor coordination ability (Beam task), anxiety (Open Field test), and learning and memory abilities (Morris Water Maze test). The closed-head mTBI model produced a consistent injury response with minimal mortality and replicated real-life situations. The validation method effectively verified the model development and ensured the stability and consistency of the model.

Author Spotlight: Advancing Traumatic Brain Injury Research - A Closed-Head Model for Accurate Replication and Rapid Assessment 

Here, we present a closed-head mild traumatic brain injury (mTBI) rat model and its validation exhibiting remarkable similarity to human mTBI concerning behavioral manifestations during the acute and subacute stages.

Animal models are crucial for advancing our understanding of mild traumatic brain injury (mTBI) and guiding clinical research. To achieve meaningful ...

rmTBI Induction in Mice via a Closed-Head Injury Method

Modified Mouse Model of Repetitive Mild Traumatic Brain Injury Incorporating Thinned-Skull Window and Fluid Percussion

Mild traumatic brain injury is a clinically highly heterogeneous neurological disorder. Highly reproducible traumatic brain injury (TBI) animal models with well-defined pathologies are urgently needed for studying the mechanisms of neuropathology after mild TBI and testing therapeutics. Replicating the entire sequelae of TBI in animal models has proven to be a challenge. Therefore, the availability of multiple animal models of TBI is necessary to account for the diverse aspects and severities seen in TBI patients. CHI is one of the most common methods for fabricating rodent models of rmTBI. However, this method is susceptible to many factors, including the impact method used, the thickness and shape of the skull bone, animal apnea, and the type of head support and immobilization utilized. The aim of this protocol is to demonstrate a combination of the thinned-skull window and fluid percussion injury (FPI) methods to produce a precise mouse model of CHI-associated rmTBI. The primary objective of this protocol is to minimize factors that could impact the accuracy and consistency of CHI and FPI modeling, including skull bone thickness, shape, and head support. By utilizing a thinned-skull window method, potential inflammation due to craniotomy and FPI is minimized, resulting in an improved mouse model that replicates the clinical features observed in patients with mild TBI. Results from behavior and histological analysis using hematoxylin and eosin (HE) staining suggest that rmTBI can lead to a cumulative injury that produces changes in both behavior and gross morphology of the brain. Overall, the modified CHI-associated rmTBI presents a useful tool for researchers to explore the underlying mechanisms that contribute to focal and diffuse pathophysiological changes in rmTBI.

Author Spotlight: Optimizing Rodent Models for Investigating the Mechanisms and Rehabilitation in Repeated Mild Traumatic Brain Injury

This protocol presents a modified mouse model of repetitive mild traumatic brain injury (rmTBI) induced via a closed-head injury (CHI) method. The approach features a thinned-skull window and fluid percussion to reduce the inflammation commonly caused by meninges exposure, along with improved reproducibility and accuracy in modeling rmTBI in rodents.

Mild traumatic brain injury is a clinically highly heterogeneous neurological disorder. Highly reproducible traumatic brain injury (TBI) animal models ...

Assessing Dominant-Submissive Behavior in Adult Rats Following Traumatic Brain Injury

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