Name: intracerebroventricular injection of amyloid-&#946; peptides in normal mice to acutely induce alzheimer-like cognitive deficits
Uploaded: 2016-03-16T13:00:00
Description: Watch this Scientific Journal Video about Intracerebroventricular Injection of Amyloid-Î² Peptides in Normal Mice to Acutely Induce Alzheimer-like Cognitive Deficits at JoVE.com

This research was supported by a grant of the Korea Health Technology R&#38;D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health &#38; Welfare, Republic of Korea (grant number: H14C04660000).

All animal experiments were carried out in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals (NIH Publications No. 8023, revised 1978) and with the Animal Care and Use Committee of the Institutional Animal Care and Use Committee of KIST (Seoul, Korea).
1. Animal Preparation
<ol>
	<li>Prepare a group of 7-week-old male ICR mice (or C57BL/6).</li>
	<li>Let the mice go through an acclimation process for 3-7 days after transport to restore homeostasis. In general, pla...

<ol>
	<li>Kam, T. I., Gwon, Y., Jung, Y. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amyloid+beta+receptors+responsible+for+neurotoxicity+and+cellular+defects+in+Alzheimer's+disease.">Amyloid beta receptors responsible for neurotoxicity and cellular defects in Alzheimer's disease.</a> Cell Mol Life Sci. 71, 4803-4813 (2014).</li><li>Elder, G. A., Gama Sosa, M. A., De Gasperi, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transgenic+mouse+models+of+Alzheimer's+disease.">Transgenic mouse models of Alzheimer's disease.</a> Mt Sinai J Med. 77, 69-81 (2010).</li><li>Bryan, K. J., Lee, H., Perry, G., Smith, M. A., Casadesus, G., Buccafusco, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Methods of Behavior Analysis in Neuroscience Frontiers in Neuroscience. , (2009).</li><li>Van Dam, D., De Deyn, P. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+in+the+drug+discovery+pipeline+for+Alzheimer's+disease.">Animal models in the drug discovery pipeline for Alzheimer's disease.</a> Br J Pharmacol. 164, 1285-1300 (2011).</li><li>Choi, J. W., Kim, H. Y., Jeon, M., Kim, D. J., Kim, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+access+to+highly+pure+beta-amyloid+peptide+by+optimized+solid-phase+synthesis.">Efficient access to highly pure beta-amyloid peptide by optimized solid-phase synthesis.</a> Amyloid. 19, 133-137 (2012).</li><li>Rahimi, F., Maiti, P., Bitan, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photo-induced+cross-linking+of+unmodified+proteins+(PICUP)+applied+to+amyloidogenic+peptides.">Photo-induced cross-linking of unmodified proteins (PICUP) applied to amyloidogenic peptides.</a> J Vis Exp. , (2009).</li><li>Kim, H. V., 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=Amelioration+of+Alzheimer's+disease+by+neuroprotective+effect+of+sulforaphane+in+animal+model.">Amelioration of Alzheimer's disease by neuroprotective effect of sulforaphane in animal model.</a> Amyloid. 20, 7-12 (2013).</li><li>Jackson, L. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=VTE+on+an+elevated+T-maze.">VTE on an elevated T-maze.</a> J Comp Psychol. 36, 9 (1943).</li><li>Kim, H. Y., 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=Taurine+in+drinking+water+recovers+learning+and+memory+in+the+adult+APP/PS1+mouse+model+of+Alzheimer's+disease.">Taurine in drinking water recovers learning and memory in the adult APP/PS1 mouse model of Alzheimer's disease.</a> Sci Rep. 4, 7467 (2014).</li><li>Paxinos, G., Franklin, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The Mouse Brain in Stereotaxic Coordinates. 2nd edn. , (2001).</li><li>Ledo, J. H., 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=Amyloid-beta+oligomers+link+depressive-like+behavior+and+cognitive+deficits+in+mice.">Amyloid-beta oligomers link depressive-like behavior and cognitive deficits in mice.</a> Mol Psychiatry. 18, 1053-1054 (2013).</li><li>Laursen, S. E., Belknap, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intracerebroventricular+injections+in+mice.+Some+methodological+refinements.">Intracerebroventricular injections in mice. Some methodological refinements.</a> J Pharmacol Methods. 16, 355-357 (1986).</li><li>Bromley-Brits, K., Deng, Y., Song, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morris+water+maze+test+for+learning+and+memory+deficits+in+Alzheimer's+disease+model+mice.">Morris water maze test for learning and memory deficits in Alzheimer's disease model mice.</a> J Vis Exp. , (2011).</li><li>Figueiredo, C. P., 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=Memantine+rescues+transient+cognitive+impairment+caused+by+high-molecular-weight+abeta+oligomers+but+not+the+persistent+impairment+induced+by+low-molecular-weight+oligomers.">Memantine rescues transient cognitive impairment caused by high-molecular-weight abeta oligomers but not the persistent impairment induced by low-molecular-weight oligomers.</a> J Neurosci. 33, 9626-9634 (2013).</li><li>Haley, T. J., McCormick, W. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pharmacological+effects+produced+by+intracerebral+injection+of+drugs+in+the+conscious+mouse.">Pharmacological effects produced by intracerebral injection of drugs in the conscious mouse.</a> Br J Pharmacol Chemother. 12, 12-15 (1957).</li><li>Harkany, T., 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=Neuroprotective+approaches+in+experimental+models+of+beta-amyloid+neurotoxicity:+relevance+to+Alzheimer's+disease.">Neuroprotective approaches in experimental models of beta-amyloid neurotoxicity: relevance to Alzheimer's disease.</a> Prog Neuropsychopharmacol Biol Psychiatry. 23, 963-1008 (1999).</li><li>Wang, D., 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=The+allosteric+potentiation+of+nicotinic+acetylcholine+receptors+by+galantamine+ameliorates+the+cognitive+dysfunction+in+beta+amyloid25-35+i.c.v.-injected+mice:+involvement+of+dopaminergic+systems.">The allosteric potentiation of nicotinic acetylcholine receptors by galantamine ameliorates the cognitive dysfunction in beta amyloid25-35 i.c.v.-injected mice: involvement of dopaminergic systems.</a> Neuropsychopharmacology. 32, 1261-1271 (2007).</li><li>Yamada, K., Nabeshima, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+Alzheimer's+disease+and+evaluation+of+anti-dementia+drugs.">Animal models of Alzheimer's disease and evaluation of anti-dementia drugs.</a> Pharmacol Ther. 88, 93-113 (2000).</li><li>Cho, S. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Correlations+of+amyloid-beta+concentrations+between+CSF+and+plasma+in+acute+Alzheimer+mouse+model.">Correlations of amyloid-beta concentrations between CSF and plasma in acute Alzheimer mouse model.</a> Sci Rep. 4, 6777 (2014).</li></ol>

The most important step in this protocol is the ICV injection of A&#946;. This protocol is designed to inject A&#946; into the ICV region of mice without stereotactic instruments11,12. Before starting an experiment, a preliminary period of practice injections with a blue dye instead of A&#946; should take place to achieve sufficient dexterity. Immediately after the injection, it is necessary to check whether the pigment injection was performed properly. Carefully take out the brain and check whether the approp...

Given that amyloid-&#946; (A&#946;) is a pathological hallmark of Alzheimer&#39;s disease (AD), the development of AD animal models has focused on neural overexpression of A&#946;. Because mutations in amyloid precursor protein (APP) or presenilin (PS) lead to disturbance of A&#946; equilibrium and ultimately to the pathogenesis of familial AD1, mouse models involving APP or PS gene mutations have been generally accepted. Among the wide range of transgenic mice, prototypical mouse models include the following: TG2576, PDAPP, APP/PS1 and APP23. In the brain, these mice generally exhibit A&#946; aggregation and eventually senile plaques; plaque formation is followed by significant cognitive impairment such that they show poor performance in behavioral tests of learning and memory. The generation of using transgenic mice that naturally mimic human AD pathology has thus contributed to AD research society by allowing us to monitor the progression of the disease. However, using transgenic mice is uneconomical and time-consuming because it takes months for the mice to develop A&#946; plaques and even longer to show A&#946;-induced synaptic or behavioral abnormalities2,3. Originally developed as an alternative to overcome the shortcomings of transgenic mouse models, non-transgenic models are also commonly used due to their distinct advantages. Pathogen-induced AD models can be produced by the direct injection of A&#946; into the brain, whereas AD-like cognitive deficits can also be triggered by other chemical and physical means-such as the injection of neurotoxic compounds such as scopolamine, the induction of lesions in cognition-related areas such as the hippocampus, or by cortical damage4. However, the non-pathogenic induction of cognitive impairment does not accurately reflect the fundamental pathophysiology of AD; instead, it only mimics its symptomatic outcomes. In contrast, a pathogen-induced AD model, the A&#946;-injected mouse model, can not only show AD-like behavioral abnormalities but can also exhibit A&#946; pathology, the common feature shared by familial and sporadic AD.
Despite the difficulty to visualize A&#946; plaques in the brain tissue, the largest benefit of the A&#946;-injected model that makes it attractive for AD investigation is its controllability. Researchers can weed out the individual differences in mouse models that can lead to erroneous data in drug-related studies. Timely drug treatment is enabled depending on the mechanism of the candidate drug; to elaborate, an inhibitor of A&#946; aggregation can be applied before the injection of A&#946;. Additionally, investigators can assume that the pathogenic transformation that arises after A&#946; injection is derived from the A&#946; exposure because the other factors are tightly controlled, including individual differences.
In this protocol, a vivid description of how to induce an AD-like phenotype in normal mice via A&#946; intracerebroventricular (ICV) injection without stereotactic instruments is presented. Minimizing insertion-provoked damage to brain tissue is essential to prevent the possibility of structural damage and lesion-induced inflammation. A lack of skill in mouse handling leads to unexpected neuronal injury. Furthermore, techniques that enable the appropriate angle and depth to be achieved during the injection are especially important to circumvent frequent mistakes. In addition to a detailed, vivid explanation of the ICV injection, the reliability of the model produced by the following protocol is also illustrated in the following sections. The following protocol could be a reliable and easily understood tool that contributes to AD research, thereby providing a steppingstone that could ultimately lead to a meaningful discovery for AD society.

<table border="0" cellpadding="0" cellspacing="0" width="1106">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:300px;">ICR mouse</td>
			<td style="width:155px;">Orientbio</td>
			<td style="width:119px;"></td>
			<td style="width:532px;">male, 6~8 weeks, 27~29 g of body weight</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">C57BL/6 mouse</td>
			<td>Orientbio</td>
			<td></td>
			<td>male, 6~8 weeks, 21~23 g of body weight</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Amyloid-beta1-42</td>
			<td>in house synthesis</td>
			<td>n.a.</td>
			<td>stock concentration: 1 mM/DMSO, injected concentration: 100 &#956;M/10% DMSO and 90% PBS</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ICV injection syringe (26s gauge)</td>
			<td>Hamilton</td>
			<td>80308</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Evans blue dye (EBD)</td>
			<td>abcamBIochemicals</td>
			<td>ab120869</td>
			<td>1 % EBD in PBS</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DMSO</td>
			<td>Sigma</td>
			<td>D2650</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">PBS</td>
			<td>gibco</td>
			<td>10010-023</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Gradi-GelTM II Gradient PAGE Analysis Kit</td>
			<td>ELPiS Biotech</td>
			<td>EBS-1056</td>
			<td>15% Gel</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Precision Plus ProteinTM Dual Xtra Standards</td>
			<td>Bio-Rad</td>
			<td>161-0377</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Silver-Staining Kit</td>
			<td>GE-Healthcare</td>
			<td>17-1150-01</td>
			<td></td>
		</tr>
	</tbody>
</table>

intracerebroventricular injection of amyloid-&#946; peptides in normal mice to acutely induce alzheimer-like cognitive deficits

Amyloid-&#946; (A&#946;) is a major pathological mediator of both familial and sporadic Alzheimer's disease (AD). In the brains of AD patients, progressive accumulation of A&#946; oligomers and plaques is observed. Such A&#946; abnormalities are believed to block long-term potentiation, impair synaptic function, and induce cognitive deficits. Clinical and experimental evidences have revealed that the acute increase of A&#946; levels in the brain allows development of Alzheimer-like phenotypes. Hence, a detailed protocol describing how to acutely generate an AD mouse model via the intracerebroventricular (ICV) injection of A&#946; is necessary in many cases. In this protocol, the steps of the experiment with an A&#946;-injected mouse are included, from the preparation of peptides to the testing of behavioral abnormalities. The process of preparing the tools and animal subjects before the injection, of injecting the A&#946; into the mouse brain via ICV injection, and of assessing the degree of cognitive impairment are easily explained throughout the protocol, with an emphasis on tips for effective ICV injection of A&#946;. By mimicking certain aspects of AD with a designated injection of A&#946;, researchers can bypass the aging process and focus on the downstream pathology of A&#946; abnormalities.

This section illustrates examples of the results that can be obtained by confirmation of A&#946; aggregation and Y-maze assessment of memory deficits. Using the full-length A&#946;(1-42) peptide of 42 amino acids, mixture of A&#946; monomers, oligomers, and fibrils (Figure 3) was produced. Through the HFIP-induced monomerization step, relatively homogeneous monomers (Lane B) were obtained. After the 7 day incubation, diverse sizes of A&#946; aggregates (Lane C) developed....

Watch this Scientific Journal Video about Intracerebroventricular Injection of Amyloid-Î² Peptides in Normal Mice to Acutely Induce Alzheimer-like Cognitive Deficits at JoVE.com

Intracerebroventricular Injection of Amyloid-&#946; Peptides in Normal Mice to Acutely Induce Alzheimer-like Cognitive Deficits

The amyloid-&#946; (A&#946;)-injected animal model enables the administration of a defined quantity and species of A&#946; fragments and reduces individual differences within each study group. This protocol describes the intracerebroventricular (ICV) injection of A&#946; without stereotactic instruments, enabling the production of Alzheimer-like behavioral abnormalities in normal mice.

Amyloid-&#946; (A&#946;) is a major pathological mediator of both familial and sporadic Alzheimer's disease (AD). In the brains of AD patients, ...

The overall goal of this surgical procedure is to conduct the intracerebroventricular injection of Amyloid beta without stereotactic instruments, and to acutely induce Alzheimer-like behavior abnormalities in normal mice. This method can help answering key questions in the field of neurobiology, such as drug discovery for Alzheimer's Disease. The main benefit of this technique is that we can perform the direct injection of A beta into the intracerebroventricle region of the mice without the help of stereotactic instruments, and it allows us to mimic Alzheimer-like behavior abnormalities in mice without waiting for the aging process.The implications of this technique extend towards therapy or diagnosis of Alzheimer's Disease, because it can be used to study the downstream pathology of Amyloid beta, and screened for drug candidates. Generally, individual new to this method will struggle, because finding the precise location of bregma on animal skull may be difficult. To begin this procedure, make one millimolar A-beta with DMSO.Then, dilute it ten fold in PBS. Next, prepare PBS solution containing 10%DMSO as a vehicle for ICV injection. After that, wrap the microsyringe with a 26-gauge stainless steel needle using Parafilm strips in order to adjust the needle length for depth-controlled injection.Densely wrap the syringe multiple times so that the Parafilm will not be compressed during needle insertion, and the needle length stays constant. Then, cut the layers of Parafilm strips to adjust the needle length to 3.8 millimeters between the needle tip and the Parafilm. Next, wash the syringe twice with 70%ethanol.Subsequently, rinse the syringe with distilled water. Dry it completely in a fume hood for at least 30 minutes, and leave the clean syringe under a UV light for another 20 minutes before injection. In this step, place a seven week old anesthetized mouse on a warm mat.Next, apply sterile PBS drops or ointment to both eyes to prevent corneal dryness during the procedure. Afterward, confirm adequate anesthesia by assessing the toe pinch extensor withdrawal reflex. Then, prepare two mirrors with multiple vertical lines drawn on the surfaces to provide references for the syringe's perpendicular injection.Place one mirror right next to the body of the mouse, and the other in front of the head. Keep M1 parallel to the imaginary midline between the two eyes of the mouse and arrange M2 perpendicular to M1, so that the two planes form a 90 degree angle. Next, spray 70%ethanol on the mouse forehead, and rub it with dry cotton swabs.To locate the bregma, place the thumb and index fingers directly above the eyes and slightly press the forehead down to the extent that both eyes protrude. At the same time, drag the skin of the forehead backwards in order to minimize the skull movement under it. Locate the injection site with a tailor's tape at 2.4 millimeters depth under the skull.Fill the syringe with 10 microliters of A-beta solution or vehicle. Place the syringe so that it is perpendicular to the plane of the injection site. Then, align the reflected images of the syringe in both mirrors with the drawn lines on the mirrors.Begin inserting the needle until the Parafilm wrapping touches the skin. Hold the syringe with one hand, and inject five microliters of the A-beta solution or vehicle with the other hand, slowly over five seconds without pausing, and make sure the syringe remains perpendicular throughout. After completing the injection, wait three to five seconds before removing the syringe.Place the thumb and index fingers back on the head, and hold it down to prevent the skull from any unneccessary movements. Then remove the syringe without tilting. Subsequently, place the mouse on a warm pad for recovery.To confirm if A-beta was injected in the target ICV region, check the trace of the needle insertion in the brain tissue to see if it reached one of the ventricles. If the injection was unsuccessful, exclude that subject's data from analysis of the experimental results. In this experiment, the full-length A-beta peptide of 42 amino acids was used to produce a mixture of A beta monomers, oligomers, and fibrils.Through the HFIP induced monomerization step, relative homogenous monomers were obtained. After the seven day incubation, diverse sizes of A-beta aggregates were developed, in which trimers and tetramers were the dominant species among the oligomeric forms of A-beta. In this study, spacial working memory was assessed in the A-beta injected mice in the Y-maze test, in which the sequence of arm choices and the number of total arm entries were recorded while each mouse was allowed to freely explore the maze.The A-beta injected mouse group showed significantly lower alternation rates, indicating the development of cognitive deficits. Once mastered, this technique can be done in 20 minutes, including anesthetic procedures, if it is performed properly. While attempting these procedures, it is important to remember to make the needle perpendicular to the plane of injection.After its development, this technique paved the way for researchers in the field of drug discovery of Alzheimer's Disease to explore in vivo screening of drug candidates in these easily accessible Alzheimer's rodent models. After watching this video, you should have a good understanding of how to conduct intracerebroventricular injection without stereotactic instruments.

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Research

JoVE Journal

Neuroscience

Intracerebroventricular Viral Injection of the Neonatal Mouse Brain for Persistent and Widespread Neuronal Transduction

With the pace of scientific advancement accelerating rapidly, new methods are needed for experimental neuroscience to quickly and easily manipulate gene expression in the mouse brain. Here we describe a technique first introduced by Passini and Wolfe for direct intracranial delivery of virally-encoded transgenes into the neonatal mouse brain. In its most basic form, the procedure requires only an ice bucket and a microliter syringe. However, the protocol can also be adapted for use with stereotaxic frames to improve consistency for researchers new to the technique. The method relies on the ability of adeno-associated virus (AAV) to move freely from the cerebral ventricles into the brain parenchyma while the ependymal lining is still immature during the first 12-24 hr after birth. Intraventricular injection of AAV at this age results in widespread transduction of neurons throughout the brain. Expression begins within days of injection and persists for the lifetime of the animal. Viral titer can be adjusted to control the density of transduced neurons, while co-expression of a fluorescent protein provides a vital label of transduced cells. With the rising availability of viral core facilities to provide both off-the-shelf, pre-packaged reagents and custom viral preparation, this approach offers a timely method for manipulating gene expression in the mouse brain that is fast, easy, and far less expensive than traditional germline engineering.

Here we demonstrate a technique for widespread neuronal transduction by intraventricular injection of adeno-associated virus into the neonatal mouse brain. This method provides a rapid and easy way to attain lifelong expression of virally-delivered transgenes.

With the pace of scientific advancement accelerating rapidly, new methods are needed for experimental neuroscience to quickly and easily manipulate gene ...

Electrophysiological Method for Recording Intracellular Voltage Responses of Drosophila Photoreceptors and Interneurons to Light Stimuli In Vivo

Voltage responses of insect photoreceptors and visual interneurons can be accurately recorded with conventional sharp microelectrodes. The method described here enables the investigator to measure long-lasting (from minutes to hours) high-quality intracellular responses from single Drosophila R1-R6 photoreceptors and Large Monopolar Cells (LMCs) to light stimuli. Because the recording system has low noise, it can be used to study variability among individual cells in the fly eye, and how their outputs reflect the physical properties of the visual environment. We outline all key steps in performing this technique. The basic steps in constructing an appropriate electrophysiology set-up for recording, such as design and selection of the experimental equipment are described. We also explain how to prepare for recording by making appropriate (sharp) recording and (blunt) reference electrodes. Details are given on how to fix an intact fly in a bespoke fly-holder, prepare a small window in its eye and insert a recording electrode through this hole with minimal damage. We explain how to localize the center of a cell's receptive field, dark- or light-adapt the studied cell, and to record its voltage responses to dynamic light stimuli. Finally, we describe the criteria for stable normal recordings, show characteristic high-quality voltage responses of individual cells to different light stimuli, and briefly define how to quantify their signaling performance. Many aspects of the method are technically challenging and require practice and patience to master. But once learned and optimized for the investigator's experimental objectives, it grants outstanding in vivo neurophysiological data.

Electrophysiological Method for Recording Intracellular Voltage Responses of Drosophila Photoreceptors and Interneurons to Light Stimuli In Vivo

Sharp microelectrodes enable accurate electrophysiological characterization of photoreceptor and visual interneuron output in living Drosophila. Here we show how to use this method to record high-quality voltage responses of individual cells to controlled light stimulation. This method is ideal for studying neural information processing in insect compound eyes.

Voltage responses of insect photoreceptors and visual interneurons can be accurately recorded with conventional sharp microelectrodes. The method ...

Whole-cell Currents Induced by Puff Application of GABA in Brain Slices

Pharmacological administration is commonly used when conducting whole-cell patch-clamp recording in brain slices. One of the best methods of drug application during electrophysiological recording is the puff technique, which can be used to study the effect of pharmacological reagents on neuronal activities in brain slices. The greatest advantage of puff application is that the drug concentration around the recording site increases rapidly, thus preventing desensitization of membrane receptors. Successful use of puff application involves careful attention to the following elements: the concentration of the drug, the parameters of the puff micropipette, the distance between the tip of a puff micropipette and the neuron recorded, and the duration and pressure driving the puff (pounds per square inch, psi). This article describes a step-by-step procedure for recording whole-cell currents induced by puffing gamma-aminobutyric acid (GABA) onto a neuron of a prefrontal cortical slice. Notably, the same procedure can be applied with minor modifications to other brain areas such as the hippocampus and the striatum, and to different preparations, such as cell cultures.

We describe the puff technique, by which pharmacological reagents can be administered during whole-cell patch-clamp recording, and highlight various aspects of the features that are crucial for its success.

Pharmacological administration is commonly used when conducting whole-cell patch-clamp recording in brain slices. One of the best methods of drug ...

Intracerebroventricular Treatment with Resiniferatoxin and Pain Tests in Mice

The transient receptor potential vanilloid type 1 (TRPV1), a thermosensitive cation channel, is known to trigger pain in the peripheral nerves. In addition to its peripheral function, its involvement in brain functions has also been suggested. Resiniferatoxin (RTX), an ultrapotent TRPV1 agonist, has been known to induce long-term desensitization of TRPV1, and this desensitization has been an alternative approach for investigating the physiological relevance of TRPV1-expressing cells. Here we describe a protocol for intracerebroventricular (i.c.v.) treatment with RTX in mice. Procedures are described for testing nociception to peripheral TRPV1 stimulation (RTX test) and mechanical stimulation (tail pressure test) then follow. Although the nociceptive responses of mice that had been administered RTX i.c.v. were comparable to those of the control groups, RTX-i.c.v.-administered mice were insensitive to the analgesic effect of acetaminophen, suggesting that i.c.v. RTX treatment can induce supraspinal-selective TRPV1 desensitization. This mouse model can be used as a convenient experimental system for studying the role of TRPV1 in brain/supraspinal function. These techniques can also be applied to studies of the central actions of other drugs.

The transient receptor potential vanilloid type 1 (TRPV1) in the supraspinal region has been suggested to play some roles in the brain function. Described here is a protocol for intracerebroventricular injection of resiniferatoxin for supraspinal TRPV1 desensitization in mice. Procedures for some pain tests are also presented.

The transient receptor potential vanilloid type 1 (TRPV1), a thermosensitive cation channel, is known to trigger pain in the peripheral nerves. In ...

Pre-Chiasmatic, Single Injection of Autologous Blood to Induce Experimental Subarachnoid Hemorrhage in a Rat Model

Despite advances in treatment over the last decades, subarachnoid hemorrhage (SAH) continues to carry a high burden of morbidity and mortality, largely afflicting a fairly young population. Several animal models of SAH have been developed to investigate the pathophysiological mechanisms behind SAH and to test pharmacological interventions. The pre-chiasmatic, single injection model in the rat presented in this article is an experimental model of SAH with a predetermined blood volume. Briefly, the animal is anesthetized, intubated, and kept under mechanical ventilation. Temperature is regulated with a heating pad. A catheter is placed in the tail artery, enabling continuous blood pressure measurement as well as blood sampling. The atlantooccipital membrane is incised and a catheter for pressure recording is placed in the cisterna magna to enable intracerebral pressure measurement. This catheter can also be used for intrathecal therapeutic interventions. The rat is placed in a stereotaxic frame, a burr hole is drilled anteriorly to the bregma, and a catheter is inserted through the burr hole and placed just anterior to the optic chiasm. Autologous blood (0.3 mL) is withdrawn from the tail catheter and manually injected. This results in a rise of intracerebral pressure and a decrease of cerebral blood flow. The animal is kept sedated for 30 min and given subcutaneous saline and analgesics. The animal is extubated and returned to its cage. The pre-chiasmatic model has a high reproducibility rate and limited variation between animals due to the pre-determined blood volume. It mimics SAH in humans making it a relevant model for SAH research.

Subarachnoid hemorrhage continues to carry a high burden of mortality and morbidity in man. To facilitate further research into the condition and its pathophysiology, a pre-chiasmatic, single injection model is presented.

Despite advances in treatment over the last decades, subarachnoid hemorrhage (SAH) continues to carry a high burden of morbidity and mortality, largely ...

Inter-Brain Synchrony in Open-Ended Collaborative Learning: An fNIRS-Hyperscanning Study

fNIRS hyperscanning is widely used to detect the neurobiological underpinnings of social interaction. With this technique, researchers qualify the concurrent brain activity of two or more interactive individuals with a novel index called inter-brain synchrony (IBS) (i.e., phase and/or amplitude alignment of the neuronal or hemodynamic signals across time). A protocol for conducting fNIRS hyperscanning experiments on collaborative learning dyads in a naturalistic learning environment is presented here. Further, a pipeline of analyzing IBS of oxygenated hemoglobin (Oxy-Hb) signal is explained. Specifically, the experimental design, the process of NIRS data recording, data analysis methods, and future directions are all discussed. Overall, implementing a standardized fNIRS hyperscanning pipeline is a fundamental part of second-person neuroscience. Also, this is in line with the call for open-science to aid the reproducibility of research.

The protocol for conducting fNIRS hyperscanning experiments on collaborative learning dyads in a naturalistic learning environment is outlined. Further, a pipeline to analyze the Inter-Brain Synchrony (IBS) of oxygenated hemoglobin (Oxy-Hb) signals is presented.

fNIRS hyperscanning is widely used to detect the neurobiological underpinnings of social interaction. With this technique, researchers qualify the ...

How to Calculate and Validate Inter-brain Synchronization in a fNIRS Hyperscanning Study

The dynamics between coupled brains of individuals have been increasingly represented by inter-brain synchronization (IBS) when they coordinate with each other, mostly using simultaneous-recording signals of brains (namely hyperscanning) with fNIRS. In fNIRS hyperscanning studies, IBS has been commonly assessed through the wavelet transform coherence (WTC) method because of its advantage on expanding time series into time-frequency space where oscillations can be seen in a highly intuitive way. The observed IBS can be further validated via the permutation-based random pairing of the trial, partner, and condition. Here, a protocol is presented to describe how to obtain brain signals via fNIRS technology, calculate IBS through the WTC method, and validate IBS by permutation in a hyperscanning study. Further, we discuss the critical issues when using the above methods, including the choice of fNIRS signals, methods of data preprocessing, and optional parameters of computations.&#160;In summary, using the WTC method and permutation is a potentially standard pipeline for analyzing IBS in fNIRS hyperscanning studies, contributing to both the reproducibility and reliability of IBS.

The dynamics between coupled brains of individuals have been increasingly represented by inter-brain synchronization (IBS) when they coordinate with each ...

Measurement of the Directional Information Flow in fNIRS-Hyperscanning Data using the Partial Wavelet Transform Coherence Method

Social interaction is of vital importance for human beings. While the hyperscanning approach has been extensively used to study interpersonal neural synchronization (INS) during social interactions, functional near-infrared spectroscopy (fNIRS) is one of the most popular techniques for hyperscanning naturalistic social interactions because of its relatively high spatial resolution, sound anatomical localization, and exceptionally high tolerance of motion artifacts. Previous fNIRS-based hyperscanning studies usually calculate a time-lagged INS using wavelet transform coherence (WTC) to describe the direction and temporal pattern of information flow between individuals. However, the results of this method might be confounded by the autocorrelation effect of the fNIRS signal of each individual. For addressing this issue, a method termed partial wavelet transform coherence (pWTC) was introduced, which aimed to remove the autocorrelation effect and maintain the high temporal-spectrum resolution of the fNIRS signal. In this study, a simulation experiment was performed first to show the effectiveness of the pWTC in removing the impact of autocorrelation on INS. Then, step-by-step guidance was offered on the operation of the pWTC based on the fNIRS dataset from a social interaction experiment. Additionally, a comparison between the pWTC method and the traditional WTC method and that between the pWTC method and the Granger causality (GC) method was drawn. The results showed that pWTC could be used to determine the INS difference between different experimental conditions and INS's directional and temporal pattern between individuals during naturalistic social interactions. Moreover, it provides better temporal and frequency resolution than the traditional WTC and better flexibility than the GC method. Thus, pWTC is a strong candidate for inferring the direction and temporal pattern of information flow between individuals during naturalistic social interactions.

This protocol describes partial wavelet transform coherence (pWTC) for calculating the time-lagged pattern of interpersonal neural synchronization (INS) to infer the direction and temporal pattern of information flow during social interaction. The effectiveness of pWTC in removing the confounds of signal autocorrelation on INS was proved by two experiments.

Social interaction is of vital importance for human beings. While the hyperscanning approach has been extensively used to study interpersonal neural ...

Dual-Task Stroop Paradigm for Detecting Cognitive Deficits in High-Functioning Stroke Patients

General clinical cognitive assessment scales are not sensitive enough to cognitive impairment in high-functioning stroke patients. The dual-task assessment has advantages for identifying cognitive deficits in high-functioning stroke patients and has been gradually applied in clinical assessment and cognitive training. Moreover, the Stroop paradigm has higher sensitivity and specificity for attentional assessment than conventional clinical cognitive assessment scales. Therefore, this study presents the dual-task assessment based on the Stroop paradigm to identify cognitive deficits in high-functioning stroke patients. This study demonstrates a single- and dual-task evaluation based on the Stroop paradigm and confirms its feasibility through case experiments and synchronized functional near-infrared spectroscopy evaluation. The Stroop reaction time and correct rate are used as the main indicators to evaluate the cognitive level of the subjects. This study protocol aims to provide new ideas to figure out the ceiling effect in general clinical assessment failure for high-functioning stroke patients.

Clinical assessment scales are notsensitive enough to cognitive dysfunction in high-functioning stroke patients. The dual-task paradigm presents advantages and potential in the assessment and cognitive training of cognitive dysfunction. The study here proposes a dual-task Stroop paradigm to identify cognitive dysfunction in high-functioning stroke patients.

General clinical cognitive assessment scales are not sensitive enough to cognitive impairment in high-functioning stroke patients. The dual-task ...

Extracellular Electrophysiological Recording in the Motor Cortex of Mice

Multichannel Extracellular Recording in Freely Moving Mice

The protocol aims to uncover the properties of neuronal firing and network local field potentials (LFPs) in behaving mice carrying out specific tasks by correlating the electrophysiological signals with spontaneous and/or specific behavior. This technique represents a valuable tool in studying the neuronal network activity underlying these behaviors. The article provides a detailed and complete procedure for electrode implantation and consequent extracellular recording in free-moving conscious mice. The study includes a detailed method for implanting the microelectrode arrays, capturing the LFP and neuronal spiking signals in the motor cortex (MC) using a multichannel system, and the subsequent offline data analysis. The advantage of multichannel recording in conscious animals is that a greater number of spiking neurons and neuronal subtypes can be obtained and compared, which allows the evaluation of the relationship between a specific behavior and the associated electrophysiological signals. Notably, the multichannel extracellular recording technique and the data analysis procedure described in the present study can be applied to other brain areas when conducting experiments in behaving mice.

Author Spotlight: Advancements in Multichannel Extracellular Recording for Studying Neuronal Activity in Freely Moving Mice 

The protocol describes the methodology of extracellular recording in the motor cortex (MC) to reveal extracellular electrophysiological properties in freely moving conscious mice, as well as the data analysis of local field potentials (LFPs) and spikes, which is useful for evaluating the network neural activity underlying behaviors of interest.

The protocol aims to uncover the properties of neuronal firing and network local field potentials (LFPs) in behaving mice carrying out specific tasks by ...