Name: investigations on alterations of hippocampal circuit function following mild traumatic brain injury
Uploaded: 2012-11-19T12:00:00
Description: Watch this Scientific Journal Video about Investigations on Alterations of Hippocampal Circuit Function Following Mild Traumatic Brain Injury at JoVE.com

The authors would like to thank Elliot Bourgeois for his technical assistance. This work was funded by the National Institutes of Health grants R01HD059288 and R01NS069629.

1. Lateral Fluid Percussion Injury
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 <li>Anaesthetize the mouse using a mixture of ketamine and xylazine given intraperitoneally. Then prepare the mouse's head for incision using an iodine scrub.</li>
 <li>Perform a craniectomy over the right parietal area using 3 mm (outside diameter) trephine.</li>
 <li>Secure Luer-loc needle hub (inside diameter 3 mm) over the craniectomy using cyanoarylate and dental acrylic.</li>
 <li>24 hr later, anaesthetize the mouse using isoflurane via inhalation.</li>
 <li>Once normal br...

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	<li>Faul, M., Xu, L., Wald, M. M., Coronado, V. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Traumatic+Brain+Injury+in+the+United+States:+Emergency+Department+Visits+Hospitalizations+and+Deaths+2002-2006.">Traumatic Brain Injury in the United States: Emergency Department Visits Hospitalizations and Deaths 2002-2006.</a> Centers for Disease Control and Prevention, National Center for Injury Prevention and Control. , (2010).</li><li>McAllister, T. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuropsychiatric+sequelae+of+head+injuries.">Neuropsychiatric sequelae of head injuries.</a> Psychiatr. Clin. North Am. 15, 395-413 (1992).</li><li>Pierce, J. E., Smith, D. H., Trojanowski, J. Q., McIntosh, T. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enduring+cognitive,+neurobehavioral+and+histopathological+changes+persist+for+up+to+one+year+following+severe+experimental+brain+injury+in+rats.">Enduring cognitive, neurobehavioral and histopathological changes persist for up to one year following severe experimental brain injury in rats.</a> NSC. 87, 359-369 (1998).</li><li>Dixon, C. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+fluid+percussion+model+of+experimental+brain+injury+in+the+rat.">A fluid percussion model of experimental brain injury in the rat.</a> J. Neurosurg. 67, 110-119 (1987).</li><li>McIntosh, T. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Traumatic+brain+injury+in+the+rat:+characterization+of+a+lateral+fluid-percussion+model.">Traumatic brain injury in the rat: characterization of a lateral fluid-percussion model.</a> Neuroscience. 28, 233-244 (1989).</li><li>Carbonell, W. S., Grady, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regional+and+temporal+characterization+of+neuronal,+glial,+and+axonal+response+after+traumatic+brain+injury+in+the+mouse.">Regional and temporal characterization of neuronal, glial, and axonal response after traumatic brain injury in the mouse.</a> Acta Neuropathol. 98, 396-406 (1999).</li><li>Toth, Z., Hollrigel, G. S., Gorcs, T., Soltesz, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Instantaneous+perturbation+of+dentate+interneuronal+networks+by+a+pressure+wave-transient+delivered+to+the+neocortex.">Instantaneous perturbation of dentate interneuronal networks by a pressure wave-transient delivered to the neocortex.</a> J. Neurosci. 17, 8106-8117 (1997).</li><li>D'Ambrosio, R., Maris, D. O., Grady, M. S., Winn, H. R., Janigro, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selective+loss+of+hippocampal+long-term+potentiation,+but+not+depression,+following+fluid+percussion+injury.">Selective loss of hippocampal long-term potentiation, but not depression, following fluid percussion injury.</a> Brain Res. 786, 64-79 (1998).</li><li>Witgen, B. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regional+hippocampal+alteration+associated+with+cognitive+deficit+following+experimental+brain+injury:+A+systems,+network+and+cellular+evaluation.">Regional hippocampal alteration associated with cognitive deficit following experimental brain injury: A systems, network and cellular evaluation.</a> Neuroscience. 133, 1-15 (2005).</li><li>Schwarzbach, E., Bonislawski, D. P., Xiong, G., Cohen, A. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+underlying+the+inability+to+induce+area+CA1+LTP+in+the+mouse+after+traumatic+brain+injury.">Mechanisms underlying the inability to induce area CA1 LTP in the mouse after traumatic brain injury.</a> Hippocampus. 16, 541-550 (2006).</li><li>Cole, J. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dietary+branched+chain+amino+acids+ameliorate+injury-induced+cognitive+impairment.">Dietary branched chain amino acids ameliorate injury-induced cognitive impairment.</a> Proceedings of the National Academy of Sciences. 107, 366-371 (2010).</li></ol>

Each technique outlined above contributes to the greater understanding of the underlying mechanism causing the observed behavioral deficit. By combining the unique information gained from each method we are able to examine the biological mechanisms with more precision.
	Measuring fEPSPs is useful for quantifying the net synaptic efficacy of large, spatially defined regions of neurons. It also can provide information about the potential of a group of cells to undergo synaptic plasticity, a ne...

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 <td>Company</td>
 <td>Catalogue number</td>
 <td>Comments (optional)</td>
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 <td>Axopatch 200B amplifier</td>
 <td>Molecular Devices</td>
 <td>AXOPATCH 200B</td>
 <td>Patch-clamp rig</td>
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 <td>Digidata 1322A digitizer</td>
 <td>Molecular Devices</td>
 <td></td>
 <td>Patch-clamp rig</td>
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 <td>MP-225 micromanipulator</td>
 <td>Sutter</td>
 <td>MP-225 </td>
 <td>Patch-clamp rig</td>
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 <td>DMLFSA microscope</td>
 <td>Leica</td>
 <td></td>
 <td>Patch-clamp rig</td>
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 <td>Multiclamp 700B amplifier</td>
 <td>Molecular Devices</td>
 <td>MULTICLAMP 700B</td>
 <td>Multipurpose (field) rig</td>
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 <td>Digidata 1440 digitizer</td>
 <td>Molecular Devices</td>
 <td></td>
 <td>Multipurpos (field) rig</td>
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 <td>MPC-200 micromanipulator</td>
 <td>Sutter</td>
 <td>MPC-200</td>
 <td>Multipurpose (field) rig</td>
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 <td>BX51WI microscope </td>
 <td>Olympus</td>
 <td>BX51WI</td>
 <td>Multipurpose (field) rig</td>
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 <td>Axoclamp 900A amplifier</td>
 <td>Molecular Devices</td>
 <td>AXOCLAMP 900A</td>
 <td>VSD rig</td>
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 <td>Digidata 1322 digitizer</td>
 <td>Molecular Devices</td>
 <td></td>
 <td>VSD rig</td>
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 <td>Redshirt CCD-SMQ camera</td>
 <td>Redshirt</td>
 <td>NCS01</td>
 <td>VSD rig</td>
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 <td>VT 1200S Vibratome</td>
 <td>Leica</td>
 <td>14048142066 </td>
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 <td>P-30 Electrode puller</td>
 <td>Sutter</td>
 <td>P-30/P </td>
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 <td>cOmplete protease inhibitor</td>
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investigations on alterations of hippocampal circuit function following mild traumatic brain injury

Traumatic Brain Injury (TBI) afflicts more than 1.7 million people in the United States each year and even mild TBI can lead to persistent neurological impairments 1. Two pervasive and disabling symptoms experienced by TBI survivors, memory deficits and a reduction in seizure threshold, are thought to be mediated by TBI-induced hippocampal dysfunction 2,3. In order to demonstrate how altered hippocampal circuit function adversely affects behavior after TBI in mice, we employ lateral fluid percussion injury, a commonly used animal model of TBI that recreates many features of human TBI including neuronal cell loss, gliosis, and ionic perturbation 4-6.
	Here we demonstrate a combinatorial method for investigating TBI-induced hippocampal dysfunction. Our approach incorporates multiple ex vivo physiological techniques together with animal behavior and biochemical analysis, in order to analyze post-TBI changes in the hippocampus. We begin with the experimental injury paradigm along with behavioral analysis to assess cognitive disability following TBI. Next, we feature three distinct ex vivo recording techniques: extracellular field potential recording, visualized whole-cell patch-clamping, and voltage sensitive dye recording. Finally, we demonstrate a method for regionally dissecting subregions of the hippocampus that can be useful for detailed analysis of neurochemical and metabolic alterations post-TBI.
	These methods have been used to examine the alterations in hippocampal circuitry following TBI and to probe the opposing changes in network circuit function that occur in the dentate gyrus and CA1 subregions of the hippocampus (see Figure 1). The ability to analyze the post-TBI changes in each subregion is essential to understanding the underlying mechanisms contributing to TBI-induced behavioral and cognitive deficits. 
	The multi-faceted system outlined here allows investigators to push past characterization of phenomenology induced by a disease state (in this case TBI) and determine the mechanisms responsible for the observed pathology associated with TBI.

Watch this Scientific Journal Video about Investigations on Alterations of Hippocampal Circuit Function Following Mild Traumatic Brain Injury at JoVE.com

Investigations on Alterations of Hippocampal Circuit Function Following Mild Traumatic Brain Injury

A multi-faceted approach to investigating functional changes to hippocampal circuitry is explained. Electrophysiological techniques are described along with the injury protocol, behavioral testing and regional dissection method. The combination of these techniques can be applied in similar fashion for other brain regions and scientific questions.

Traumatic Brain Injury (TBI) afflicts more than 1.7 million people in the United States each year and even mild TBI can lead to persistent neurological ...

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