This method paper was funded by Eranet Neuron Neuvasc (Badaut), Agence Nationale de la Recherche Nanospace (Badaut), CNRS IRP IINOVAtion (Badaut) and NIH NINDS Grant No. 1R01NS119605 (Obenaus, Badaut) and 1RF1NS138032 (Obenaus, Territo).&#160;Figure 1 is created with BioRender.com.

Experiments were reproduced on 2 sites, the University of Bordeaux (France) and the University of California Riverside (CA, USA).
In Bordeaux, all experiments were performed on male and female P17 C57Bl6J mice bred in the University animal facility. Initial breeders were obtained from a commercial source and raised under standard conditions with a 12/12-h dark/light cycle, a temperature of 21 &#176;C &#177; 1 &#176;C, and a humidity of 55% &#177; 10%, and food and water provided ad libitum. Experimental procedures are in accordance with the University of Bordeaux Animal Care Committee regulations, French laws governing laboratory animal use (authorization #29324-2021012118549817 v3), the European Council directives (86/609/EEC), and the ARRIVE guidelines. This protocol, being a mild model of traumatic brain injury, does not produce pain or distress. As such, it does not necessitate any specific pain management outside of regular pain management. Weaning of the pups (TBI, Shams) was effective at P25.
At Riverside, E13 pregnant C57Bl6J female mice were commercially obtained, and all experiments were performed on the resultant litters in both male and female pups aged P17. Animals were raised with an automated 12/12-h dark/light cycle and a temperature of 21 &#176;C. Dams and pups had ad libitum access to food and water. All experimental procedures were approved by the University of California, Riverside Institutional Animal Care and Use Committee and complied with the Animal Welfare Act and Public Health Service policy. All pups (TBI, Sham) in that facility were weaned on P21.
The details of the animals, reagents, and equipment used in this study are listed in the Table of Materials.
1. Preliminary steps
<ol>
	<li>To prevent hypothermia, warm up the chamber for anesthesia induction and the recovery cages in advance with warming pads.</li>
	<li>Set the stereotaxic apparatus with the impactor mounted at a 90&#176; angle.</li>
	<li>Verify that all parts are properly tightened and secured and that the piston is firmly screwed to the impactor.</li>
	<li>Cut an aluminum sheet that will fit the stereotaxic apparatus (in this case, 18 cm x 30 cm). The aluminum used here is of standard aluminum quality. Wrap the stereotaxic frame with the foil to form a pad on which the animal will be laid on. Secure the position and tension of the foil with regular lab tape in order to sustain the weight of the animal.</li>
	<li>Turn on the impactor controller and, in the function of the severity of the injury, set the speed of impact to 2 m.s-1 for grade 1 (G1) or 3 m.s-1 for grade 2 (G2) for a more severe impact (modifying this parameter will impact the severity of the concussion).</li>
	<li>Weight out the animals. At P17, the weight of the animals must be over 5.9 g for C57Bl6 mice. Animals that fall under that weight are excluded. 
	NOTE: For some studies, CD1 mice were used, and for P17, the threshold was fixed to be over 6.5 g (personal data).</li>
</ol>
2. Juvenile mild traumatic brain injury procedure
<ol>
	<li>Anesthetize the mouse with a 5 min exposure to isoflurane. Set the gas composition to a 2.5% mixture (in this case, the carrier is a synthetic air mixture with 21% oxygen) with a flow rate of 1.5 L/min. 
	NOTE: From this step, all the actions must be done swiftly, as unimpacted animals will wake up within 5 min.</li>
	<li>Position the mouse head under the impactor. The pup should be spread out at all lengths. The tip is 3 mm in diameter and covered with rubber to minimize the effect of the metal on the skull.</li>
	<li>Lower the impactor by switching the knob to the Extend position.</li>
	<li>Roughly lower the impactor and position the mouse so that the impactor is just between the ears. Then, slide the mouse so that the piston tip is moved forward to the equivalent of one piston tip, and one piston tip to the left of the animal (see Figure 1). 
	NOTE: Sham animals are positioned slightly away from the piston (no part of the animal should be impacted).</li>
	<li>Lower the impactor so that it contacts the head of the animal (Figure 1E2).</li>
	<li>Set the impactor to Retract (Figure 1E3).</li>
	<li>In order to determine the severity of the injury, move the piston 1 mm down for grade 1 (G1). For more severe impact grade 2 (G2), move the piston 3 mm down (Figure 1E4).</li>
	<li>Set the dwell time to 0.1 s regardless of the severity (modifying this parameter will not impact the severity of the concussion).</li>
	<li>Press Impact on the right knob (Figure 1E5).</li>
	<li>Rapidly set the left knob to the off position so that the system doesn&#39;t overheat. See the flow chart for more information (Figure 2).</li>
</ol>
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/67667/67667fig01.jpg" /> 
Figure 1: Positioning of the impactor tip. (A) The impactor tip is first positioned on the midline between the ears. (B) The tip is then moved 3 mm forward (the equivalent of a tip diameter). (C) Finally, the piston tip is moved 3 mm on the left side of the mouse. (D,E) Possible positions of the impactor tip in regard to the magnetic barrel. (D) The impactor has 3 positions in relation to the piston body (neutral, retracted, or extended/impact) with 5 mm range between them. (E) Positions of the impactor tip in relation to the skull surface at the different stages of the procedure. (1) Position of the impactor in the neutral position; (2) the piston is moved to gently touch the skull of the animal (step 2.5); (3) the impactor is then set to retract (step 3.6); (4) the whole body of the impactor is moved of x mm down (step 2.7). For G1 grade, a speed of impact (y) of 2 m.s-1 with 1 mm depth (x) for G1 or a speed of impact (y) of 3 m.s-1 with 3 mm (x) depth for G2. (5) Once the lever impact is pressed, the impactor tip moves x mm below the skull surface at a y speed during dwell time upon moving back to the neutral position. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/67667/67667fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/67667/67667fig02.jpg" /> 
Figure 2: CHILD flow chart. Flow chart detailing the steps to induce CHILD in PND17 mice color-coded to denote different phases of concussion induction. Photographs of the setup include (A) the entire CHILD induction setup (anesthesia device is not visible), including the Impact controller, the stereotactic device with the impactor and tip positioned above taut tin foil, and the recovery box located on top of a heating pad. (B) Rubber impact tip (3 mm) with scale. (C) The stereotactic device with tin foil stretched across the stereotactic frame and the impactor solenoid with the impact tip positioned above the foil. (D) Recovery chamber sitting on the heat pad. (E) The impact controller with two control switches, highlighted as in the flow chart (red box = extend/retract/off; purple box= impact toggle). <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/67667/67667fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
3. Post-trauma follow-up
NOTE: The following steps can be videorecorded for offline analysis, allowing the experimenter to perform CHILD on multiple animals in a row. Nonetheless, regular and repeated assessments of animal well-being should be performed.
<ol>
	<li>Note the duration of apnea, if present (immediately after impact), and if there was a head rotation during impact.</li>
	<li>Position the mouse on its right flank in a recovery cage.</li>
	<li>Note the righting time of the mouse (rearing on 4 legs) and the time of resuming an exploratory behavior. Typically, sham mice awake within 3-4 min and resume an exploratory behavior 3-4 min later (Figure 3). CHILD mice awake within 7-12 min after impact (Figure 3A) and resume exploration within 12-18 min after impact (Figure 3B), according to the sex and impact severity (Figure 3A,B). 
	NOTE: If the impacted animal doesn&#39;t resume its exploratory behavior within 30 min, the animal is excluded.</li>
	<li>Once fully recovered, return the animals to their home cage. At this point, the behavior of sham and CHILD mice (G1 or G2 severity) should be exactly similar, and animal groups shouldn&#39;t be distinguishable within the litter. 
	NOTE: The animals can be maintained up to 18 months post-injury14 in conditions indicated at the beginning of the methods. Behavioral outcomes assessments can be performed using a battery of tests in association with MRI measurements, miniscope imaging, histology, and immunohistochemistry12. Immunohistochemistry for GFAP and NeuN can be used at early time points to validate the model and the presence of tissue changes.</li>
</ol>
4. Immunohistochemistry
NOTE: One day post-injury, animals from the G2 and sham groups (n = 4 mice for G2 and n = 4 for Sham) were anesthetized and transcardially perfused with 4% paraformaldehyde (PFA) prepared in phosphate-buffered saline (PBS) 0.1 M, pH 7.4 at 4 &#176;C. Brains were extracted10 from the skull and immersed in the same PFA solution overnight, and then transferred to PBS with sodium azide (0.1%) before cutting. Coronal sections were then prepared at 50 &#181;m thickness using a vibratome. For long storage, sections were placed in cryoprotective medium (30% ethylene glycol and 20% glycerol in PBS) at -20 &#176;C until use. To characterize the impact of the concussion on brain gliosis and neuronal loss, immunohistochemistry targeting GFAP and NeuN was performed as described here below.
<ol>
	<li>Wash the brain sections 4 times for 10 min in PBS.</li>
	<li>Transfer the sections in blocking solution (1% BSA, 0,3% Triton X-100 in PBS) for 10 min at room temperature (RT).</li>
	<li>Incubate sections overnight at 4 &#176;C with the following primary antibodies diluted in blocking solution: chicken anti-GFAP (1:3000) and rabbit anti-NeuN (1:500).</li>
	<li>Wash the slices 4 times for 10 min in PBS under agitation.</li>
	<li>Then, transfer the sections in blocking solution containing the secondary fluorescent antibodies diluted 1:1000 for 1 h at RT, Alexa-Fluor-488-nm goat anti-rabbit, and Alexa-Fluor-568-nm goat anti-chicken.</li>
	<li>Wash then the sections 4 times for 10 min in PBS under agitation.</li>
	<li>Mount the sections on slides using a mounting medium and add a cover slip. Keep the slides at 4 &#176;C until the image acquisition.</li>
	<li>Aquire immunofluorescence using an epifluorescence microscope and micromanager software. Use a stitching plugin with a 10x lens to obtain tiled images of ipsilateral and contralateral hemispheres. 
	NOTE: Negative control staining where the primary antibody or secondary antibody was omitted showed no detectable labeling. For more detailed image analysis, Fiji software15 can be used to quantify the immunostaining parameters in various regions of interest16.</li>
</ol>

CHILD Model &#8212; Recapitulating Juvenile Concussion and Long-Term Outcomes in Mice

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The authors have nothing to disclose.

Critical steps in the protocol 
The CHILD protocol described here requires the use of an electromagnetic impactor (Figure 2A) that (1) standardizes the impact parameters (speed, depth, duration), (2) ensures reproducibility within and across laboratories, and (3) is readily available commercially. Another critical component is the impactor tip that strikes the rodent&#39;s head. A variety of possibilities can be used, ranging from silicone to metal tips, but this protocol utilizes a rubber tip obtained from the plunger of a 2 mL syringe (Figure 2B). The rationale for a rubber tip is to deliver the force and rotation of the impact to the skull but without eliciting skull fractures. In G2 mice, a small subset exhibited skull fractures, with or without associated subdural bleeding. Using an electromagnetic impactor also provides the opportunity to manipulate speed/duration along with the depth of the impact to modulate severity, as done in the G1 and G2 designations. The impactor position on the head should be carefully aligned for reproducibility, however, small location differences do not have a major effect on the injury outcomes as head rotation significantly contributes to the pathophysiological process.
Another critical component is the medium on which the mouse is placed during the head impact. There are a variety of reports that use different materials, from foam to paper, but here, aluminum foil is used. The rationale for using aluminum foil is that it does not break upon impact delivery. The thickness of the aluminum foil is important to provide some resistance to the impact but also allows for sufficient head movement and rotation. We have previously documented the head movement and rotation in the initial publication10.
When the brain is extracted from the skull case 1 day post-trauma, no visible bleeding or skull fracture should be observed at the G1 severity level. As noted above and published10, a G2 impact can lead to micro-bleeding in some mice located between the neocortex and corpus callosum. Note that G1 or G2 impacts induce similar righting times (see Figure 3A). The clinical literature concludes that neuroimaging should present no observable change on anatomical MRI scans; in the previously published studies, neuroimaging changes were not observed in G110. A feature of the CHILD model is that more severe/moderate grades of closed-head injury (CHI) can be derived if needed. If more severe CHI is utilized, the presence of extravascular blood would have a direct effect on brain tissue with a potential loss of neurons at day 1 and accompanied by increased GFAP staining. In the absence of visible bleeding or gross morphological changes on day 1 after the G2 protocol, GFAP staining was increased in the cortex compared to sham mice (Figure 4A). GFAP changes are a critical landmark in the CHILD model at 1 day post-injury10,16 and persisted over time at 30 days16 and 12 months post-injury18.
Modifications and troubleshooting 
As indicated, the absence of skull fracture and visible intracranial bleeding are critical landmarks for designation as a concussion model. If either is detected, the parameters of the impactor, including the depth of impact, should be modified. It is possible to (1) modify the speed of the impactor (decrease to limit the risk of skull fracture), (2) change the rubber on the tip to make it softer and more dampening to minimize skull fracture, and (3) evaluate the depth of the impact which can be decreased to reduce the displacement and rotation of the head. The consequence of the change in impact depth would be a decreased risk for intracranial bleeding. The experimental conditions described above could be easily modified in older animals with similar results. As shown in the results above, the protocol works well on either sex with a sex difference in injury recovery.
Limitations 
This CHILD protocol was developed to minimize anesthesia exposure and invasiveness without surgery to visualize the bregma landmarks. While the decreased invasiveness of the CHI and very short recovery times after the impact (Figure 3) are a strength, a limitation is the potential variability of positioning the impactor tip in the absence of bregma landmarks. The advantage of this model is that without surgery and a fast procedure, it allows for the repeat of the procedure on a high number of animals compared to more invasive procedures, hence accounting for the possible variability of the CHILD model. The current CHILD model has been tested and validated in a number of studies using a juvenile mouse that has a certain skull thickness. This study observed that mice with a weight &#60;5.9 g exhibited significantly longer recovery time (&#60;30 min) and also displayed a more severe phenotype (personal observations). Therefore, it is suggested that only juvenile mice &#62;6.0 g should be included for consistency of the CHILD model and limit skull fracture10. It should be noted that adapting the CHILD model to rats would require a new set of ad hoc parameters to obtain a similar concussion model.
The significance of the method with respect to existing/alternative methods 
There are various methods to induce mTBI using a closed-head approach. It is important to highlight that a majority of the mTBI models were developed and used in adult rodents8. Little CHI model development has been undertaken in young rodents, and mostly in rats (P20 old rats, Closed-Head Injury Model of Engineered Rotational Acceleration (CHIMERA) model22). Here, a simple model well-suited for young mice between P17 and 18 is proposed that can be easily extended at P20 and that elicits long-term alterations18. It has been demonstrated that two severities have long-term consequences on the outcomes of the animals, including changes in tissue properties, including neuronal hyperactivity12, inflammation, and vascular and cerebrovascular alterations10,11,12,13,14,16,18. The CHILD model is uniquely positioned due to its ease of implementation and no requirement for surgery skills. In addition to the labs in Bordeaux and UC riverside, the reproducibility of the CHILD model in other labs is also reported (i.e., Montpellier13).
Importance and potential applications of the method in specific research areas 
A new model of concussion in the juvenile mouse is proposed here to mimic clinical pediatric features, including head rotation and absence of major neuronal cell death (Figure 4B); no bleeding was assessed with MRI10. The current model can be repeated at repeated time points (for repeated mTBI), and the impact location can vary according to the investigators&#39; region of interest. As shown, we developed various severities, Grade 1 (G1) and Grade 2 (G2), both of which exhibited mTBI or concussion phenotypes, based on the outcomes measured. The absence of mortality10 and the possibility of monitoring the mice over a long time post-injury, at least up to 18 months in our hands, are a plus14.
In the context of preclinical study reproducibility, it has been established that multi-laboratory studies have higher quality, less bias, and greater rigor in study design than single laboratory work23.&#160;In our consortium (funded by NINDS Grant No. 1R01NS119605 (Obenaus, Badaut) and 1RF1NS138032 (Obenaus, Territo)), it has been demonstrated that the CHILD model was reproducible between sites with the absence of difference on the recovery parameters. These data strongly suggest that the CHILD model can be widely used in various research groups as well as in larger multi-laboratory studies. The CHILD model is a useful model for multigroup studies for drug development as well as for gaining a better understanding of the pathophysiological processes at play.

Pediatric Traumatic Brain Injury (TBI) is a major health concern as it represents the leading cause of pediatric emergency medical care visits and is associated with debilitating health outcomes later in life. Even mild TBI (mTBI), which makes up 75% of all TBI cases1, leads to long-term abnormalities, including physiological, psychological, neurological, and cognitive dysfunctions2. Despite the high occurrence of pediatric mTBI and its significant associated health risks, the pathological, cellular, and molecular mechanisms that precede the chronic deficits are still underexplored. This gap in knowledge impedes the development of effective treatments and diagnostic methods for pediatric mTBI.
Adult rodent TBI models include weight drop, controlled cortical impact, and fluid percussion injury and can be titrated to elicit moderate to severe injuries (dependent upon outcome measures)3,4. Many of these adult models have been adapted for pediatric TBI5,6. During the last decade, models of mTBI have been developed in rodents with closed head injury as well as with rotational models7. However, implementation of these models in developing rodents is sparse compared to the adult TBI literature8. To address the clinical relevance, encompassing a wide range of severities that model pediatric clinical heterogeneity, this study developed the Closed Head Injury with Long-term Disorder (CHILD) TBI model. CHILD is a non-surgical, unrestrained concussion model using P17 mice, a developmental age that corresponds to the peak of myelination observed in 2-3-year-old children9. A concussive force is delivered using an electromagnetic impactor over the somatosensory cortex of a lightly isoflurane-anesthetized mouse. Impacting the unrestrained head results in rotational forces on the brain10, as reported in many clinical concussion reports. Consistent with clinical mTBI, the CHILD model does not lead to skull fracture or visible abnormality on conventional neuroimaging.
The CHILD model has several advantages. First, both early and long-term pathological features have been observed in CHILD, mimicking the pathological clinical features observed in juvenile concussion patients. It has been observed at late time points gliosis, altered diffusion tensor MRI, and progressive behavioral perturbations with age10,11, modified neuronal activity, and plasticity11,12. Interestingly, unsuspected peripheral consequences were also found with cardiac abnormalities in the long term after a single pediatric injury13. Second, this model is replicable and showed comparable results between researchers and between labs13. Third, the CHILD model is flexible and can be expanded to encapsulate the heterogeneous nature of TBIs. For instance, previous studies have shown that different speeds and depths of impact result in different severities10,11. Finally, an additional strength of this model is that CHILD can be administered repeatedly and can be easily applied to differential locations to probe responses to repeated injury and identify vulnerable brain regions.
Overall, the CHILD model replicates clinical pediatric mTBI and concussion and serves as a research tool to facilitate the understanding of the pathophysiological characteristics of pediatric mTBI. While no model encapsulates every aspect of the features described in real-life TBI cases, this model can address many of the outstanding research questions that remain unanswered.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>BSA</td>
			<td>Sigma Aldrich Chimie S.a.r.l 
			80 Rue de Luzais 
			L&#39;lsle-d&#39;Abeau Chesnes - BP701 
			38297 Saint-Quentin-Fallavier Cedex 
			France</td>
			<td>A7030</td>
			<td></td>
		</tr>
		<tr>
			<td>C57Bl6J mice&#160;</td>
			<td>Charles River Laboratory France CRLF 9 All. Moulin Berger, 69130 &#201;cully, France</td>
			<td></td>
			<td>Bordeaux</td>
		</tr>
		<tr>
			<td>Electromagnetic impactor</td>
			<td>Leica Biosystems, Richmond, IL USA</td>
			<td>Impact One stereotaxic impactor</td>
			<td></td>
		</tr>
		<tr>
			<td>Epifluorescence microscope</td>
			<td>Olympus, BX41, Center Valley, PA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ethylen glycol</td>
			<td>Sigma Aldrich Chimie S.a.r.l 
			80 Rue de Luzais 
			L&#39;lsle-d&#39;Abeau Chesnes - BP701 
			38297 Saint-Quentin-Fallavier Cedex 
			France</td>
			<td>102466</td>
			<td></td>
		</tr>
		<tr>
			<td>GFAP primary antibody</td>
			<td>Millipore, Billerica, MA</td>
			<td>AB5541</td>
			<td>chicken anti-GFAP</td>
		</tr>
		<tr>
			<td>GFAP secondary antibody</td>
			<td>Molecular Probes, Invitrogen</td>
			<td>A11034</td>
			<td>goat anti-rabbit AlexaFluor&#160; 488</td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Sigma Aldrich Chimie S.a.r.l 
			80 Rue de Luzais 
			L&#39;lsle-d&#39;Abeau Chesnes - BP701 
			38297 Saint-Quentin-Fallavier Cedex 
			France</td>
			<td>G5516</td>
			<td></td>
		</tr>
		<tr>
			<td>Heavy duty aluminium foil</td>
			<td>Kirkland</td>
			<td>RK611</td>
			<td>obtained at Cosco</td>
		</tr>
		<tr>
			<td>Micromanager software&#160;</td>
			<td>(NIH, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>NeuN primary antibody</td>
			<td>AbCam, Discovery Drive, Cambridge 
			Biomedical Campus, 
			Cambridge, CB2 0AX, UK</td>
			<td>AB128886</td>
			<td>rabbit anti-NeuN</td>
		</tr>
		<tr>
			<td>NeuN secondary antibody</td>
			<td>Molecular Probes, Invitrogen</td>
			<td>A11041</td>
			<td>goat anti-chicken AlexaFluor 568</td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>Sigma Aldrich Chimie S.a.r.l 
			80 Rue de Luzais 
			L&#39;lsle-d&#39;Abeau Chesnes - BP701 
			38297 Saint-Quentin-Fallavier Cedex 
			France</td>
			<td>P5493</td>
			<td></td>
		</tr>
		<tr>
			<td>PFA</td>
			<td>Sigma Aldrich Chimie S.a.r.l 
			80 Rue de Luzais 
			L&#39;lsle-d&#39;Abeau Chesnes - BP701 
			38297 Saint-Quentin-Fallavier Cedex 
			France</td>
			<td>1.04003</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium azide</td>
			<td>Sigma Aldrich Chimie S.a.r.l 
			80 Rue de Luzais 
			L&#39;lsle-d&#39;Abeau Chesnes - BP701 
			38297 Saint-Quentin-Fallavier Cedex 
			France</td>
			<td>26628-22-8</td>
			<td></td>
		</tr>
		<tr>
			<td>Stereotaxic frame - base</td>
			<td>KOPF instruments 7324 Elmo St, Tujunga, CA 91042, &#201;tats-Unis</td>
			<td>900-C</td>
			<td></td>
		</tr>
		<tr>
			<td>Stereotaxic frame - electrode manipulator</td>
			<td>KOPF instruments 7324 Elmo St, Tujunga, CA 91042, &#201;tats-Unis</td>
			<td>960</td>
			<td></td>
		</tr>
		<tr>
			<td>Stereotaxic frame - u-frame</td>
			<td>KOPF instruments 7324 Elmo St, Tujunga, CA 91042, &#201;tats-Unis</td>
			<td>900-U</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton x-100</td>
			<td>Sigma Aldrich Chimie S.a.r.l 
			80 Rue de Luzais 
			L&#39;lsle-d&#39;Abeau Chesnes - BP701 
			38297 Saint-Quentin-Fallavier Cedex 
			France</td>
			<td>X100</td>
			<td></td>
		</tr>
		<tr>
			<td>Vectashield</td>
			<td>Vector laboratories</td>
			<td>H-1000-10</td>
			<td>Mounting medium</td>
		</tr>
		<tr>
			<td>Vibratome</td>
			<td>Leica Biosystems, Richmond, IL USA</td>
			<td>VTS1000</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td>Jackson laboratory The Jackson Laboratory 600 Main Street Bar Harbor, ME USA 04609</td>
			<td></td>
			<td>UCR</td>
		</tr>
	</tbody>
</table>

a pediatric concussion model in mice: closed head injury with long-term disorders (child)

Concussions and mild traumatic brain injuries (mTBI) during childhood represent a significant health endangerment, with many patients later in life exhibiting debilitating physiological, neurological, and psychosocial outcomes. The cellular and molecular pathophysiological mechanisms are relatively unknown, and this significant gap effectively precludes investigations into specific therapeutic strategies to mitigate chronic sequelae. No single animal concussion model recapitulates all the features reported in human subjects, and current models are designed to answer specific research questions. We set out to develop a juvenile concussion that recapitulates clinical early, and long-term symptomology encountered, termed Closed Head Injury with Long-term Disorder (CHILD). In this model, a concussive force via an electromagnetic impactor is delivered to the head of a lightly anesthetized unrestrained post-natal day 17 (P17) mouse, allowing free rotation of the head. Mice are placed on a tightly stretched tin foil across a stereotactic device, and the impactor is carefully aligned with the targeted cortical region. The electromagnetic impactor facilitates the selection of impact depth, dwell, and duration to determine injury severity. A strength of this model is that it allows head rotation, an important clinical feature. After impact, mice are immediately monitored for righting time and time to explore their environment, followed by their return to their dam. Increasing the severity of concussion results in intracranial bleeds in a subset of mice. Mice can be routinely monitored for behavior and neuroimaging over their lifespan, as desired. Various injury severities mimic the heterogeneous nature of juvenile concussions. The current standard CHILD model exhibits no skull fracture, no observable conventional neuroimaging change (similar to clinical), but leads to progressive and persistent neuronal death, altered diffusion MRI, modified neuronal activity and plasticity, increased gliosis, and progressive behavioral perturbations with age. In summary, this CHILD model mimics the early and long-term features observed in many clinical concussion patients.

The CHILD model is a relatively rapid and reproducible model of mTBI in pediatric mice, also allowing for variations in severity and location. The CHILD mice, as expected, exhibited significantly longer recovery times from closed head injury (Figure 3). When cohorts (n = 36 female sham, n = 140 male sham, n = 30 female G1, n = 55 male G1, n = 32 female G2, n = 141 male G2) were aggregated, a delay in righting time was observed (Figure 3A, 3-way ANOVA p &#60; 0.001) and in the time to resume exploratory behaviors (Figure 3B, 3-way ANOVA p &#60; 0.001). The recovery period was also dependent upon the impact severity (Figure 3, G1 vs G2; 3-way ANOVA, p &#60; 0.001 for both parameters). Sex effects were clearly observed with age-matched females exhibiting a prolonged recovery time compared to males in both righting time (3-way ANOVA, p &#60; 0.01) and time to exploration (Figure 3, 3-way ANOVA, p &#60; 0.001). Interestingly, there were no within-sex differences between injury severities (G1 vs G2).
Preclinical model development requires reproducibility to allow for wider dissemination between research groups. Two laboratories (Badaut, France; Obenaus, USA) undertook comparisons for reproducibility. Using righting times and time resume exploratory behavior for comparisons, no significant difference was found, suggesting the reproducibility of G2 CHILD between two different sites (see Table 1).
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/67667/67667fig03.jpg" /> 
Figure 3: Recovery times in the CHILD model for G1 and G2 severity grades. Parameters used were a dwell time of 0.1 s, and a speed of impact of 2 m.s-1 with 1 mm depth for G1 or a speed of impact of 3 m.s-1 with 3 mm depth for G2. (A) Righting time measured as the time to stand on the 4 paws after impact. (B) Time to resume an exploratory behavior from impact. Data are mean &#177; SD, number of animals per group are denoted in (A). &#167;&#167;&#167;, indicates a significant difference compared to the sham counterparts (p &#60; 0.001), * and *** indicate a significant difference between males and females for each severity level (p &#60; 0.05 and p &#60; 0.001 respectively), #, ##, ### indicate significant effects and interaction between severity and sex (p &#60; 0.05, p &#60; 0.01 and p &#60; 0.001 respectively). <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/67667/67667fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
A hallmark in preclinical models of mild traumatic brain injuries is the development of astrogliosis16,17 that remains long after the initial injury18. In addition, studies in children and adults have reported substantive increases after mild to severe TBI in acute (days) biomarker assessments of glial fibrillary astrocytic protein (GFAP) from serum19,20,21. As previously reported10, after CHILD induction, astrogliosis was evident 1 day after injury in the ipsilateral somatosensory cortex (Figure 4A), compared to shams. At the 1-day time point, there was no significant loss of neurons (NeuN immunohistochemistry). For analytical details, please refer to Cl&#233;ment et al.16.
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/67667/67667fig04.jpg" /> 
Figure 4: Induction of astrogliosis GFAP immunolabelling pattern changes at 1 day after impact in the CHILD model. (A)&#160;GFAP immunolabelling was performed to assess changes in GFAP-positive astrocytes. The top is a low-magnification picture with rectangular frames corresponding to the zoom-in pictures of the bottom row. In the sham group (left), GFAP immunolabelling was present in the glia limitans, corpus callosum, and stratum radiatum.&#160;In the CHILD group (right), concussion induced an increase in the number of GFAP-positive astrocytes in the superficial cortical layers (delimitation by the dotted line) and hippocampal stratum radiatum compared to the sham group.(B) In order to assess the consequences of the CHILD model on neurons, NeuN immunostaining was performed to show the nuclei in the different cortical layers and in the hippocampus.&#160;There was no significant difference between the sham (left) and CHILD (right) groups in neuronal markers expression. Scale bars: 1 mm, magnified: 100 &#181;m. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/67667/67667fig04large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Site</td>
			<td>Gender</td>
			<td>Group</td>
			<td>n</td>
			<td>Time to stand (s)</td>
			<td>Time to explore (s)</td>
		</tr>
		<tr>
			<td rowspan="4">U Bordeaux</td>
			<td rowspan="2">females</td>
			<td>Sham</td>
			<td>36</td>
			<td>195.8 &#177; 29.1</td>
			<td>427.6 &#177; 38.2</td>
		</tr>
		<tr>
			<td>CHILD G2</td>
			<td>32</td>
			<td>737.4 &#177; 101.4</td>
			<td>1123.1 &#177; 97.3</td>
		</tr>
		<tr>
			<td rowspan="2">males</td>
			<td>Sham</td>
			<td>140</td>
			<td>207.7 &#177; 21.6</td>
			<td>429.6 &#177; 22.0</td>
		</tr>
		<tr>
			<td>CHILD G2</td>
			<td>141</td>
			<td>468.1 &#177; 30.7</td>
			<td>846.1 &#177; 30.8</td>
		</tr>
		<tr>
			<td rowspan="4">UC Riverside</td>
			<td rowspan="2">females</td>
			<td>Sham</td>
			<td>8</td>
			<td>18.8 &#177; 10.8</td>
			<td>79.8 &#177; 36.2</td>
		</tr>
		<tr>
			<td>CHILD G2</td>
			<td>30</td>
			<td>724.8 &#177; 53.2</td>
			<td>922.7 &#177; 54.0</td>
		</tr>
		<tr>
			<td rowspan="2">males</td>
			<td>Sham</td>
			<td>11</td>
			<td>88.5 &#177; 55.4</td>
			<td>114.9 &#177; 54.8</td>
		</tr>
		<tr>
			<td>CHILD G2</td>
			<td>37</td>
			<td>697.7 &#177; 53.0</td>
			<td>929.9 &#177; 58.0</td>
		</tr>
	</tbody>
</table>
Table 1: Between sites comparisons for righting time and time to explore parameters.

A Pediatric Concussion Model in Mice: Closed Head Injury with Long-Term Disorders (CHILD)

Pediatric concussions can result in long-term sequelae with physiological and psychological perturbations. This pediatric concussion mouse model results in long-term neuroinflammation, white matter alterations, and neuronal modifications with behavioral dysfunction. The model can be adapted to differential impact locations or repeated concussions to assess lifetime changes.

Concussions and mild traumatic brain injuries (mTBI) during childhood represent a significant health endangerment, with many patients later in life ...

a-pediatric-concussion-model-mice-closed-head-injury-with-long-term

Nanyang Technological University

Research

JoVE Journal

Neuroscience

268 Views.  UMR 7372 CNRS/Université de La Rochelle. Pediatric concussions can result in long-term sequelae with physiological and psychological perturbations. This pediatric concussion mouse model results in long-term neuroinflammation, white matter alterations, and neuronal modifications with behavioral dysfunction. The model can be adapted to differential impact locations or repeated concussions to assess lifetime changes.

Video: A Pediatric Concussion Model in Mice: Closed Head Injury with Long-Term Disorders (CHILD)

A Molecular Readout of Long-term Olfactory Adaptation in C. elegans

During sustained stimulation most sensory neurons will adapt their response by decreasing their sensitivity to the signal. The adaptation response helps shape attention and also protects cells from over-stimulation. Adaptation within the olfactory circuit of C. elegans was first described by Colbert and Bargmann1,2. Here, the authors defined parameters of the olfactory adaptation paradigm, which they used to design a genetic screen to isolate mutants defective in their ability to adapt to volatile odors sensed by the Amphid Wing cells type C (AWC) sensory neurons. When wildtype C. elegans animals are exposed to an attractive AWC-sensed odor3 for 30 min they will adapt their responsiveness to the odor and will then ignore the adapting odor in a chemotaxis behavioral assay for ~1 hr. When wildtype C. elegans animals are exposed to an attractive AWC-sensed odor for ~1 hr they will then ignore the adapting odor in a chemotaxis behavioral assay for ~3 hr. These two phases of olfactory adaptation in C. elegans were described as short-term olfactory adaptation (induced after 30 min odor exposure), and long-term olfactory adaptation (induced after 60 min odor exposure). Later work from L'Etoile et al.,4 uncovered a Protein Kinase G (PKG) called EGL-4 that is required for both the short-term and long-term olfactory adaptation in AWC neurons. The EGL-4 protein contains a nuclear localization sequence that is necessary for long-term olfactory adaptation responses but dispensable for short-term olfactory adaptation responses in the AWC4. By tagging EGL-4 with a green fluorescent protein, it was possible to visualize the localization of EGL-4 in the AWC during prolonged odor exposure. Using this fully functional GFP-tagged EGL-4 (GFP::EGL-4) molecule we have been able to develop a molecular readout of long-term olfactory adaptation in the AWC5. Using this molecular readout of olfactory adaptation we have been able to perform both forward and reverse genetic screens to identify mutant animals that exhibit defective subcellular localization patterns of GFP::EGL-4 in the AWC6,7. Here we describe: 1) the construction of GFP::EGL-4 expressing animals; 2) the protocol for cultivation of animals for long-term odor-induced nuclear translocation assays; and 3) the scoring of the long-term odor-induced nuclear translocation event and recovery (re-sensitization) from the nuclear GFP::EGL-4 state.

A Molecular Readout of Long-term Olfactory Adaptation in C. elegans

Here we describe a molecular readout of long-term olfactory adaptation in Caenorhabditis elegans. The Protein Kinase G, EGL-4, is necessary for stable adaptation responses in the primary sensory neuron pair called AWC. During prolonged odor exposure EGL-4 translocates from the cytosol to nucleus of the AWC.

During sustained stimulation most sensory neurons will adapt their response by decreasing their sensitivity to the signal. The adaptation response helps ...

Olfactory Neurons Obtained through Nasal Biopsy Combined with Laser-Capture Microdissection: A Potential Approach to Study Treatment Response in Mental Disorders

Bipolar disorder (BD) is a severe neuropsychiatric disorder with poorly understood pathophysiology and typically treated with the mood stabilizer, lithium carbonate. Animal studies as well as human genetic studies indicate that lithium affects molecular targets that are involved in neuronal growth, survival and maturation, and notably molecules involved in Wnt signaling. Given the ethical challenge to obtaining brain biopsies for investigating dynamic molecular changes associated with lithium-response in the central nervous system (CNS), one may consider the use of neurons obtained from olfactory tissues to achieve this goal.The olfactory epithelium contains olfactory receptor neurons at different stages of development and glial-like supporting cells. This provides a unique opportunity to study dynamic changes in the CNS of patients with neuropsychiatric diseases, using olfactory tissue safely obtained from nasal biopsies. To overcome the drawback posed by substantial contamination of biopsied olfactory tissue with non-neuronal cells, a novel approach to obtain enriched neuronal cell populations was developed by combining nasal biopsies with laser-capture microdissection. In this study, a system for investigating treatment-associated dynamic molecular changes in neuronal tissue was developed and validated, using a small pilot sample of BD patients recruited for the study of the molecular mechanisms of lithium treatment response.

In this study, a novel platform to investigate intraneuronal molecular signatures of treatment response in bipolar disorder (BD) was developed and validated. Olfactory epithelium from BD patients was obtained through nasal biopsies. Then laser-capture microdissection was combined with Real Time RT PCR to investigate the molecular signature of lithium response in BD.

Bipolar disorder (BD) is a severe neuropsychiatric disorder with poorly understood pathophysiology and typically treated with the mood stabilizer, lithium ...

Long-term Time Lapse Imaging of Mouse Cochlear Explants

Here we present a method for long-term time-lapse imaging of live embryonic mouse cochlear explants. The developmental program responsible for building the highly ordered, complex structure of the mammalian cochlea proceeds for around ten days. In order to study changes in gene expression over this period and their response to pharmaceutical or genetic manipulation, long-term imaging is necessary. Previously, live imaging has typically been limited by the viability of explanted tissue in a humidified chamber atop a standard microscope. Difficulty in maintaining optimal conditions for culture growth with regard to humidity and temperature has placed limits on the length of imaging experiments. A microscope integrated into a modified tissue culture incubator provides an excellent environment for long term-live imaging. In this method we demonstrate how to establish embryonic mouse cochlear explants and how to use an incubator microscope to conduct time lapse imaging using both bright field and fluorescent microscopy to examine the behavior of a typical embryonic day (E) 13 cochlear explant and Sox2, a marker of the prosensory cells of the cochlea, over 5 days.

Live imaging of the embryonic mammalian cochlea is challenging because the developmental processes at hand operate on a temporal gradient over ten days. Here we present a method for culturing and then imaging embryonic cochlear explant tissue taken from a fluorescent reporter mouse over five days.

Here we present a method for long-term time-lapse imaging of live embryonic mouse cochlear explants. The developmental program responsible for building ...

A Method to Inflict Closed Head Traumatic Brain Injury in Drosophila

Traumatic brain injury (TBI) affects millions of people each year, causing impairment of physical, cognitive, and behavioral functions and death. Studies using Drosophila have contributed important breakthroughs in understanding neurological processes. Thus, with the goal of understanding the cellular and molecular basis of TBI pathologies in humans, we developed the High Impact Trauma (HIT) device to inflict closed head TBI in flies. Flies subjected to the HIT device display phenotypes consistent with human TBI such as temporary incapacitation and progressive neurodegeneration. The HIT device uses a spring-based mechanism to propel flies against the wall of a vial, causing mechanical damage to the fly brain. The device is inexpensive and easy to construct, its operation is simple and rapid, and it produces reproducible results. Consequently, the HIT device can be combined with existing experimental tools and techniques for flies to address fundamental questions about TBI that can lead to the development of diagnostics and treatments for TBI. In particular, the HIT device can be used to perform large-scale genetic screens to understand the genetic basis of TBI pathologies.

A Method to Inflict Closed Head Traumatic Brain Injury in Drosophila

Here we describe a method to inflict closed head traumatic brain injury (TBI) in Drosophila. This method provides a gateway to investigate the cellular and molecular mechanisms that underlie TBI pathologies using the vast array of experimental tools and techniques available for flies.

Traumatic brain injury (TBI) affects millions of people each year, causing impairment of physical, cognitive, and behavioral functions and death. Studies ...

Automated Gait Analysis in Mice with Chronic Constriction Injury

The von Frey test is a classical method that has been widely used to examine the sensory function of neuropathic pain animals. However, it has some disadvantages such as subjective data and the requirement of a skilled, experienced experimenter. To date, a variety of modifications have improved the von Frey method, but it still has a few limitations. Recent reports have suggested that gait analysis produces more accurate and objective data from the neuropathic animals. This protocol demonstrates how to perform the automated gait analysis to determine the degree of neuropathic pain in mice. After several days of acclimation, the mice were allowed to walk freely on the glass floor to illuminate footprints. Then, quantification of the footprints and gait were performed through video clips with automatic analysis of various walking parameters, such as area of paw print, swing time, angle of paw, etc.
The main purpose of this study is to describe the methodology of automated gait analysis and briefly compare it with data from the classical sensory test using von Frey filament.

The precise assessment of pain response in a neuropathic animal model is critical to investigate the pathophysiology of pain diseases and develop new analgesics. We present a sensitive and objective method to determine the sensory function of the rodent hind paw by an automated gait analysis system.

The von Frey test is a classical method that has been widely used to examine the sensory function of neuropathic pain animals. However, it has some ...

Conducting Hyperscanning Experiments with Functional Near-Infrared Spectroscopy

Concurrent brain recordings of two or more interacting persons, an approach termed hyperscanning, are gaining increasing importance for our understanding of the neurobiological underpinnings of social interactions, and possibly interpersonal relationships. Functional near-infrared spectroscopy (fNIRS) is well suited for conducting hyperscanning experiments because it measures local hemodynamic effects with a high sampling rate and, importantly, it can be applied in natural settings, not requiring strict motion restrictions. In this article, we present a protocol for conducting fNIRS hyperscanning experiments with parent-child dyads and for analyzing brain-to-brain synchrony. Furthermore, we discuss critical issues and future directions, regarding the experimental design, spatial registration of the fNIRS channels, physiological influences and data analysis methods. The described protocol is not specific to parent-child dyads, but can be applied to a variety of different dyadic constellations, such as adult strangers, romantic partners or siblings. To conclude, fNIRS hyperscanning has the potential to yield new insights into the dynamics of the ongoing social interaction, which possibly go beyond what can be studied by examining the activities of individual brains.

The present protocol describes how to conduct fNIRS hyperscanning experiments and analyze brain-to-brain synchrony. Further, we discuss challenges and possible solutions.

Concurrent brain recordings of two or more interacting persons, an approach termed hyperscanning, are gaining increasing importance for our understanding ...

Long-term Sensory Conflict in Freely Behaving Mice

Long-term sensory conflict protocols are a valuable means of studying motor learning. The presented protocol produces a persistent sensory conflict for experiments aimed at studying long-term learning in mice. By permanently wearing a device fixed on their heads, mice are continuously exposed to a sensory mismatch between visual and vestibular inputs while freely moving in home cages. Therefore, this protocol readily enables the study of the visual system and multisensory interactions over an extended timeframe that would not be accessible otherwise. In addition to lowering the experimental costs of long-term sensory learning in naturally behaving mice, this approach accommodates the combination of in vivo and in vitro experiments. In the reported example, video-oculography is performed to quantify the vestibulo-ocular reflex (VOR) and optokinetic reflex (OKR) before and after learning. Mice exposed to this long-term sensory conflict between visual and vestibular inputs presented a strong VOR gain decrease but exhibited few OKR changes. Detailed steps of device assembly, animal care, and reflex measurements are hereby reported.

The presented protocol produces a persistent sensory conflict for experiments aimed at studying long-term learning. By permanently wearing a fixed device on their heads, mice are continuously exposed to a sensory mismatch between visual and vestibular inputs while freely moving in home cages.

Long-term sensory conflict protocols are a valuable means of studying motor learning. The presented protocol produces a persistent sensory conflict for ...

Low-intensity Blast Wave Model for Preclinical Assessment of Closed-head Mild Traumatic Brain Injury in Rodents

Traumatic brain injury (TBI) is a large-scale public health problem. Mild TBI is the most prevalent form of neurotrauma and accounts for a large number of medical visits in the United States. There are currently no FDA-approved treatments available for TBI. The increased incidence of military-related, blast-induced TBI further accentuates the urgent need for effective TBI treatments. Therefore, new preclinical TBI animal models that recapitulate aspects of human blast-related TBI will greatly advance the research efforts into the neurobiological and pathophysiological processes underlying mild to moderate TBI as well as the development of novel therapeutic strategies for TBI.
Here we present a reliable, reproducible model for the investigation of the molecular, cellular, and behavioral effects of mild to moderate blast-induced TBI. We describe a step-by-step protocol for closed-head, blast-induced mild TBI in rodents using a bench-top setup consisting of a gas-driven shock tube equipped with piezoelectric pressure sensors to ensure consistent test conditions. The benefits of the setup that we have established are its relative low-cost, ease of installation, ease of use and high-throughput capacity. Further advantages of this non-invasive TBI model include the scalability of the blast peak overpressure and the generation of controlled reproducible outcomes. The reproducibility and relevance of this TBI model has been evaluated in a number of downstream applications, including neurobiological, neuropathological, neurophysiological and behavioral analyses, supporting the use of this model for the characterization of processes underlying the etiology of mild to moderate TBI.

We present here a protocol of a blast wave model for rodents to investigate neurobiological and pathophysiological effects of mild to moderate traumatic brain injury. We established a gas-driven, bench-top setup equipped with pressure sensors allowing for reliable and reproducible generation of blast-induced mild to moderate traumatic brain injury.

Traumatic brain injury (TBI) is a large-scale public health problem. Mild TBI is the most prevalent form of neurotrauma and accounts for a large number of ...

Electromagnetic Controlled Closed-Head Model of Mild Traumatic Brain Injury in Mice

Highly reproducible animal models of traumatic brain injury (TBI), with well-defined pathologies, are needed for testing therapeutic interventions and understanding the mechanisms of how a TBI alters brain function. The availability of multiple animal models of TBI is necessary to model the different aspects and severities of TBI seen in people. This manuscript describes the use of a midline closed head injury (CHI) to develop a mouse model of mild TBI. The model is considered mild because it does not produce structural brain lesions based on neuroimaging or gross neuronal loss. However, a single impact creates enough pathology that cognitive impairment is measurable at least 1 month after injury. A step-by-step protocol to induce a CHI in mice using a stereotaxically guided electromagnetic impactor is defined in the paper. The benefits of the mild midline CHI model include the reproducibility of the injury-induced changes with low mortality. The model has been temporally characterized up to 1 year after the injury for neuroimaging, neurochemical, neuropathological, and behavioral changes. The model is complementary to open skull models of controlled cortical impact using the same impactor device. Thus, labs can model both mild diffuse TBI and focal moderate-to-severe TBI with the same impactor.

The protocol describes mild traumatic brain injury in a mouse model. In particular, a step-by-step protocol to induce a mild midline closed head injury and the characterization of the animal model is fully explained.

Highly reproducible animal models of traumatic brain injury (TBI), with well-defined pathologies, are needed for testing therapeutic interventions and ...

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 ...