Name: coherent anti-stokes raman spectroscopy (cars) application for imaging myelination in brain slices
Uploaded: 2022-07-22T14:00:00
Description: Watch this Scientific Journal Video about Coherent Anti-Stokes Raman Spectroscopy CARS Application for Imaging Myelination in Brain Slices at JoVE.com

Supported by NIH R01 DC 17924, R01 DC 18401 (Klug), and NIH 1R15HD105231-01, T32DC012280, and FRAXA (McCullagh). The CARS imaging was performed in the Advanced Light Microscopy Core part of the NeuroTechnology Center at the University of Colorado Anschutz Medical Campus supported in part by NIH P30 NS048154 and NIH P30 DK116073.

All experiments complied with all applicable laws, National Institutes of Health guidelines, and were approved by the University of Colorado Anschutz Institutional Animal Care and Use Committee.
1. Animals
<ol>
	<li>Use C57BL/6J (stock #000664) mice (Mus musculus) obtained from The Jackson Laboratory or Mongolian gerbils (Meriones unguiculatus) originally obtained from Charles River.</li>
</ol>
2. Tissue preparation</p...

<ol>
	<li>Cole, K., Curtis, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electric+impedance+of+the+squid+giant+axon+during+activity.">Electric impedance of the squid giant axon during activity.</a> The Journal of General Physiology. 22 (5), 649-670 (1939).</li><li>Cole, K. S., Curtis, H. 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G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integrative+properties+and+design+principles+of+axons.">Integrative properties and design principles of axons.</a> International Review of Neurobiology. 18, 1-40 (1975).</li><li>Fitzhugh, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Computation+of+impulse+initiation+and+saltatory+conduction+in+a+myelinated+nerve+fiber.">Computation of impulse initiation and saltatory conduction in a myelinated nerve fiber.</a> Biophysical Journal. 2 (1), 11-21 (1962).</li><li>Zalc, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+acquisition+of+myelin:+a+success+story.">The acquisition of myelin: a success story.</a> Novartis Foundation Symposium. 276, 275-281 (2006).</li><li>Salzer, J. L., Zalc, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myelination.">Myelination.</a> Current Biology. 26 (20), 971-975 (2016).</li><li>Boullerne, A. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+history+of+myelin.">The history of myelin.</a> Experimental Neurology. 283, 431-445 (2016).</li><li>Kuhn, S., Gritti, L., Crooks, D., Dombrowski, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oligodendrocytes+in+development,+myelin+generation+and+beyond.">Oligodendrocytes in development, myelin generation and beyond.</a> Cells. 8 (11), 1424 (2019).</li><li>Saab, A. S., Nave, K. -. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myelin+dynamics:+protecting+and+shaping+neuronal+functions.">Myelin dynamics: protecting and shaping neuronal functions.</a> Current Opinion in Neurobiology. 47, 104-112 (2017).</li><li>Chomiak, T., Hu, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=What+is+the+optimal+value+of+the+g-Ratio+for+myelinated+fibers+in+the+rat+CNS?+A+theoretical+approach.">What is the optimal value of the g-Ratio for myelinated fibers in the rat CNS? A theoretical approach.</a> PLOS ONE. 4 (11), 7754 (2009).</li><li>Ford, M. C., 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=Tuning+of+Ranvier+node+and+internode+properties+in+myelinated+axons+to+adjust+action+potential+timing.">Tuning of Ranvier node and internode properties in myelinated axons to adjust action potential timing.</a> Nature Communications. 6, 8073 (2015).</li><li>Stange-Marten, A., 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=Input+timing+for+spatial+processing+is+precisely+tuned+via+constant+synaptic+delays+and+myelination+patterns+in+the+auditory+brainstem.">Input timing for spatial processing is precisely tuned via constant synaptic delays and myelination patterns in the auditory brainstem.</a> Proceedings of the National Academy of Sciences of the United States of America. 114 (24), 4851-4858 (2017).</li><li>Bu, J., Banki, A., Wu, Q., Nishiyama, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Increased+NG2++glial+cell+proliferation+and+oligodendrocyte+generation+in+the+hypomyelinating+mutant+shiverer.">Increased NG2+ glial cell proliferation and oligodendrocyte generation in the hypomyelinating mutant shiverer.</a> Glia. 48 (1), 51-63 (2004).</li><li>Pacey, L. K. 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=Delayed+myelination+in+a+mouse+model+of+fragile+X+syndrome.">Delayed myelination in a mouse model of fragile X syndrome.</a> Human Molecular Genetics. 22 (19), 3920-3930 (2013).</li><li>Green, A. J., 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=Clemastine+fumarate+as+a+remyelinating+therapy+for+multiple+sclerosis+(ReBUILD):+a+randomised,+controlled,+double-blind,+crossover+trial.">Clemastine fumarate as a remyelinating therapy for multiple sclerosis (ReBUILD): a randomised, controlled, double-blind, crossover trial.</a> Lancet. 390 (10111), 2481-2489 (2017).</li><li>Jeon, S. J., Ryu, J. H., Bahn, G. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Altered+translational+control+of+fragile+X+mental+retardation+protein+on+myelin+proteins+in+neuropsychiatric+disorders.">Altered translational control of fragile X mental retardation protein on myelin proteins in neuropsychiatric disorders.</a> Biomolecules &amp; Therapeutics. 25 (3), 231-238 (2017).</li><li>Barak, B., 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=Neuronal+deletion+of+Gtf2i,+associated+with+Williams+syndrome,+causes+behavioral+and+myelin+alterations+rescuable+by+a+remyelinating+drug.">Neuronal deletion of Gtf2i, associated with Williams syndrome, causes behavioral and myelin alterations rescuable by a remyelinating drug.</a> Nature Neuroscience. 22 (5), 700-708 (2019).</li><li>Phan, B. N., 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+myelin-related+transcriptomic+profile+is+shared+by+Pitt-Hopkins+syndrome+models+and+human+autism+spectrum+disorder.">A myelin-related transcriptomic profile is shared by Pitt-Hopkins syndrome models and human autism spectrum disorder.</a> Nature Neuroscience. 23 (3), 375-385 (2020).</li><li>Lucas, A., Poleg, S., Klug, A., McCullagh, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myelination+deficits+in+the+auditory+brainstem+of+a+mouse+model+of+fragile+X+syndrome.">Myelination deficits in the auditory brainstem of a mouse model of fragile X syndrome.</a> Frontiers in Neuroscience. 15, 1536 (2021).</li><li>Wang, H., Fu, Y., Zickmund, P., Shi, R., Cheng, J. -. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coherent+anti-stokes+raman+scattering+imaging+of+axonal+myelin+in+live+spinal+ttissues.">Coherent anti-stokes raman scattering imaging of axonal myelin in live spinal ttissues.</a> Biophysical Journal. 89 (1), 581-591 (2005).</li><li>Kim, S. -. 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=Multiplex+coherent+anti-stokes+raman+spectroscopy+images+intact+atheromatous+lesions+and+concomitantly+identifies+distinct+chemical+profiles+of+atherosclerotic+lipids.">Multiplex coherent anti-stokes raman spectroscopy images intact atheromatous lesions and concomitantly identifies distinct chemical profiles of atherosclerotic lipids.</a> Circulation Research. 106 (8), 1332-1341 (2010).</li><li>Gage, G. J., Kipke, D. R., Shain, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Whole+animal+perfusion+fixation+for+rodents.">Whole animal perfusion fixation for rodents.</a> Journal of Visualized Experiments. (65), e3564 (2012).</li><li>Tu, L., 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=Free-floating+Immunostaining+of+Mouse+Brains.">Free-floating Immunostaining of Mouse Brains.</a> Journal of Visualized Experiments. (176), e62876 (2021).</li><li>. Fluorescence SpectraViewer Available from: <a target="_blank" href="https://www.thermofisher.com/order/fluorescence-spectraviewer">https://www.thermofisher.com/order/fluorescence-spectraviewer</a> (2022)</li><li>Held, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Die+centrale+geh&#246;rleitung.">Die centrale geh&#246;rleitung.</a> Arch Anat Physiol Anat Abt. 17, 201-248 (1893).</li><li>Sherman, D. L., Brophy, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+of+axon+ensheathment+and+myelin+growth.">Mechanisms of axon ensheathment and myelin growth.</a> Nature Reviews Neuroscience. 6 (9), 683-690 (2005).</li><li>Gruchot, J., 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+molecular+basis+for+remyelination+failure+in+multiple+sclerosis.">The molecular basis for remyelination failure in multiple sclerosis.</a> Cells. 8 (8), 825 (2019).</li><li>Rivera, A. 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=Epidermal+growth+factor+pathway+in+the+age-related+decline+of+oligodendrocyte+regeneration.">Epidermal growth factor pathway in the age-related decline of oligodendrocyte regeneration.</a> Frontiers in Cellular Neuroscience. 16, 838007 (2022).</li><li>K&#250;tna, V., O'Leary, V. B., Hoschl, C., Ovsepian, S. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebellar+demyelination+and+neurodegeneration+associated+with+mTORC1+hyperactivity+may+contribute+to+the+developmental+onset+of+autism-like+neurobehavioral+phenotype+in+a+rat+model.">Cerebellar demyelination and neurodegeneration associated with mTORC1 hyperactivity may contribute to the developmental onset of autism-like neurobehavioral phenotype in a rat model.</a> Autism Research: Official Journal of the International Society for Autism Research. 15 (5), 791-805 (2022).</li><li>Ozsv&#225;r, A., 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=Quantitative+analysis+of+lipid+debris+accumulation+caused+by+cuprizone+induced+myelin+degradation+in+different+CNS+areas.">Quantitative analysis of lipid debris accumulation caused by cuprizone induced myelin degradation in different CNS areas.</a> Brain Research Bulletin. 137, 277-284 (2018).</li><li>Prineas, J. 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A growing body of literature emphasizes the role of myelin in brain function13,16,21,28. Moreover, we know that myelination thickness and myelination pattern can change in several neurological conditions such as multiple sclerosis (reviewed in29), aging (reviewed in30), autism20,31, and ma...

Action potentials are the basic unit of information in the brain, and action potential propagation through axons forms one pillar of information processing1,2,3. Neurons typically receive afferent inputs from multiple other neurons and integrate these inputs within a given narrow time window4,5. Therefore, the mechanisms of action potential propagation in axons have received a significant amount of attention from investigators.
When propagating through an axon, an action potential is regenerated repeatedly along the axon to ensure reliable propagation6. In most neurons of jawed vertebrates (gnathostomes) axons are surrounded by a sheath of myelin, which is a lipid-rich substance produced by nearby oligodendrocytes or Schwann cells, which are types of glial cells (reviewed in7,8). This myelin sheath electrically insulates the axon, reducing its capacitance and allowing action potential propagation efficiently, quickly, and with lower energy consumption. Myelin does not cover the axon uniformly, but it sheaths the axon in segments that have short gaps in between them, called the nodes of Ranvier (reviewed in9,10). Both myelination thickness, which controls the level of electrical insulation of an axon, and the spacing of the nodes of Ranvier, which control the frequency with which action potentials are regenerated along an axon, influence the speed of action potential propagation (reviewed in11).
There is a large body of literature suggesting that myelination thickness affects the speed of action potential propagation in axons12,13,14. Moreover, alterations in axon myelination can result in a number of CNS deficits15,16,17,18,19,20,21. It is therefore not surprising that the focus of many research efforts involves the measurement and characterization of axon myelination. Measurements of myelin thickness have most commonly been done with electron microscopy, a technique that requires a significant amount of tissue preparation and is challenging to use in combination with immunohistochemistry. However, there is also a faster and simpler technique to measure axon myelination that is based on Coherent Anti-Stokes Raman Spectroscopy (CARS). A CARS laser can be tuned to various frequencies and when tuned to frequencies that are suitable to excite lipids, myelin can be imaged without the need for any additional labels22. The lipid imaging can be combined with standard immunohistochemistry such that lipids can be imaged together with several fluorescent channels23. Imaging myelination with CARS is significantly faster than electron microscopy and has a resolution that is, albeit lower than EM, sufficient to detect even small differences in myelination in the same type of axons.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Anesthetic:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>1 mL disposable syringe with needle 27 GA x 0.5&#34;</td>
			<td>Exel int</td>
			<td>260040</td>
			<td></td>
		</tr>
		<tr>
			<td>Fatal +</td>
			<td>Vortech</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Surgery:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Spring Scissors - 8mm Cutting Edge</td>
			<td>Fine Science Tools</td>
			<td>15024-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Standard tweezers</td>
			<td>Fine Science Tools</td>
			<td>11027-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Perfusion:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>4% Paraformaldehyde</td>
			<td>Fisher Chemical</td>
			<td>SF994 (CS)</td>
			<td></td>
		</tr>
		<tr>
			<td>Fine Scissors - Sharp</td>
			<td>Fine Science Tools</td>
			<td>14063-11</td>
			<td></td>
		</tr>
		<tr>
			<td>Kelly hemostats</td>
			<td>Fine Science Tools</td>
			<td>13019-14</td>
			<td></td>
		</tr>
		<tr>
			<td>Millipore H2O</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Needle tip, 23 GA x 1&#34;</td>
			<td>BD precision glide</td>
			<td>305193</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate buffered saline (PBS):</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium chloride</td>
			<td>Sigma</td>
			<td>P9333</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium phosphate monobase</td>
			<td>Sigma</td>
			<td>P5655</td>
			<td></td>
		</tr>
		<tr>
			<td>pump with variable flow or equivalent</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium chloride</td>
			<td>Fisher Chemical</td>
			<td>s271-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodiumphosphate dibasic</td>
			<td>Sigma</td>
			<td>S7907</td>
			<td></td>
		</tr>
		<tr>
			<td>Dissection:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>50 mL vial with 4% PFA</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bochem Chemical Spoon 180mm</td>
			<td>Bochem</td>
			<td>230331000</td>
			<td></td>
		</tr>
		<tr>
			<td>Fine Scissors - Sharp</td>
			<td>Fine Science Tools</td>
			<td>14063-11</td>
			<td></td>
		</tr>
		<tr>
			<td>Noyes Spring Scissors</td>
			<td>Fine Science Tools</td>
			<td>15011-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Pair of fine (Graefe) tweezers</td>
			<td>Fine Science Tools</td>
			<td>11050-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Shallow glass or plastic tray, approximately 10&#34; x 10&#34;</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Standard tweezers</td>
			<td>Fine Science Tools</td>
			<td>11027-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical Scissors - Blunt</td>
			<td>Fine Science Tools</td>
			<td>14000-20</td>
			<td></td>
		</tr>
		<tr>
			<td>Slicing:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Agar, plant</td>
			<td>RPI</td>
			<td>9002-18-0</td>
			<td></td>
		</tr>
		<tr>
			<td>Vibratome</td>
			<td>Leica</td>
			<td>VT1000s</td>
			<td></td>
		</tr>
		<tr>
			<td>well plate</td>
			<td>Alkali Sci.</td>
			<td>TPN1048-NT</td>
			<td></td>
		</tr>
		<tr>
			<td>Staining:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>AB Media:</td>
			<td></td>
			<td></td>
			<td>1n 1,000 mL of Millipore H2O</td>
		</tr>
		<tr>
			<td>Phosphate buffered (PB):</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium Phosphate Monobase</td>
			<td>Sigma</td>
			<td>P5655</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Phosohate Dibasic</td>
			<td>Sigma</td>
			<td>S7907</td>
			<td></td>
		</tr>
		<tr>
			<td>BSA (Bovine serum albumin)</td>
			<td>Sigma life science</td>
			<td>A2153-100g</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Chloride</td>
			<td>Fisher Chemical</td>
			<td>s271-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Sigma - Aldrich</td>
			<td>x100-500ml</td>
			<td></td>
		</tr>
		<tr>
			<td>Nissl 435/455</td>
			<td>Invitrogen</td>
			<td>N21479</td>
			<td></td>
		</tr>
		<tr>
			<td>CARS:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>APE&#160;picoemerald laser</td>
			<td>Angewandte Physik &#38; Elektronik&#160;GmbH</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>bandpass filter (420-520 nm)</td>
			<td>Chroma Technology</td>
			<td>HQ470/100m-2P</td>
			<td></td>
		</tr>
		<tr>
			<td>bandpass filter (500-530 nm)</td>
			<td>Chroma Technology</td>
			<td>HQ515/30m-2P</td>
			<td></td>
		</tr>
		<tr>
			<td>bandpass filters (640-680 nm)</td>
			<td>Chroma Technology</td>
			<td>HQ660/40m-2P</td>
			<td></td>
		</tr>
		<tr>
			<td>Confocal microscope</td>
			<td>Olympus</td>
			<td>FV1000</td>
			<td></td>
		</tr>
		<tr>
			<td>Cut Transfer pipet</td>
			<td>Fisher</td>
			<td>13-711-7M</td>
			<td></td>
		</tr>
		<tr>
			<td>dichroic longpass 565 nm</td>
			<td>Chroma Technology</td>
			<td>565dcxr</td>
			<td></td>
		</tr>
		<tr>
			<td>dichroic longpass 585 nm</td>
			<td>Chroma Technology</td>
			<td>585dcxr</td>
			<td></td>
		</tr>
		<tr>
			<td>dichroic shortpass 750 nm</td>
			<td>Chroma Technology</td>
			<td>T750spxrxt</td>
			<td></td>
		</tr>
		<tr>
			<td>glass bottom culture dish</td>
			<td>MatTek</td>
			<td>P35G-0-10-C</td>
			<td></td>
		</tr>
		<tr>
			<td>glass weight (10 mm x 10 mm boro rod)</td>
			<td>Allen Scientific Glass Inc</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>multiphoton shortpass emission filter 680 nm</td>
			<td>Chroma Technology</td>
			<td>ET680sp-2p8</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

coherent anti-stokes raman spectroscopy (cars) application for imaging myelination in brain slices

Coherent anti-Stokes Raman spectroscopy (CARS) is a technique classically employed by chemists and physicists to produce a coherent signal of signature vibrations of molecules. However, these vibrational signatures are also characteristic of molecules within anatomical tissue such as the brain, making it increasingly useful and applicable for Neuroscience applications. For example, CARS can measure lipids by specifically exciting chemical bonds within these molecules, allowing for quantification of different aspects of tissue, such as myelin involved in neurotransmission. In addition, compared to other techniques typically used to quantify myelin, CARS can also be set up to be compatible with immunofluorescent techniques, allowing for co-labeling with other markers such as sodium channels or other components of synaptic transmission. Myelination changes are an inherently important mechanism in demyelinating diseases such as multiple sclerosis or other neurological conditions such as Fragile X Syndrome or autism spectrum disorders is an emerging area of research. In conclusion, CARS can be utilized in innovative ways to answer pressing questions in Neuroscience and provide evidence for underlying mechanisms related to many different neurological conditions.

One of the biggest advantages of CARS microscopy over other techniques is the compatibility with fluorescent imaging23. Figure 1 shows the CARS spectra compared to Nissl tagged with immunofluorescent marker showing little/no overlap in spectra. Figure 2 illustrates the laser set up for CARS in combination with confocal microscopy. Figure 3 demonstrates two representative images, one as a single stack and one ...

Watch this Scientific Journal Video about Coherent Anti-Stokes Raman Spectroscopy CARS Application for Imaging Myelination in Brain Slices at JoVE.com

Coherent Anti-Stokes Raman Spectroscopy CARS Application for Imaging Myelination in Brain Slices

Visualizing myelination is an important goal for many researchers studying the nervous system. CARS is a technique that is compatible with immunofluorescence that can natively image lipids within tissue such as the brain illuminating specialized structures such as myelin.

Coherent Anti-Stokes Raman Spectroscopy (CARS) Application for Imaging Myelination in Brain Slices

Coherent anti-Stokes Raman spectroscopy (CARS) is a technique classically employed by chemists and physicists to produce a coherent signal of signature ...

This technique can image myelin in brain tissue sections. myelination plays an important role in the conduction of action potentials and understanding myelin will help us understand brain function. The main advantage of the CARS technique over, for example, electron microscopy is that CARS is a light microscopy technique, and can easily be combined with other fluorescence imaging, such as used in immunohistochemistry.Several medical conditions are due to alterations in myelination, for example, multiple sclerosis, aging, and autism. Understanding these alterations will help us understand the underlying medical conditions. In this case, the CARS laser is tuned to image lipids or, specifically, CH2 bonds.In the brain, the largest source of lipids is myelin. Thus, this is a technique to image myelin in brain tissue. It should be possible to use the same method for other types of tissue when imaging lipids is of interest.Tuning and aligning the CARS laser requires significant expertise, and is best performed by a laser or light microscopy expert. After preparing the tissues as described in the manuscript, stain free-floating sections for nisel and antibody media to visualize cell bodies, then incubate the sections on a standard laboratory shaker for 30 minutes at room temperature. Before bringing the samples to the microscope, turn on and warm up the CARS laser for at least one hour, then align the CARS laser by spatially overlapping the pump and stokes laser beams, and adjust the delay between the two laser beams.Color the condenser optics and the diaphragm of the microscope for forward CARS imaging, then adjust the external periscope to center the spatially overlapped two lasers onto the scanning head mirrors of the microscope. For best forward CARS non-descanned detection. make sure the condenser is color lured.For immunofluorescence, confocal imaging, and cars imaging, fit the CARS laser with both forward and epi CARS non-descanned detectors by incorporating a confocal microscope equipped with visible lasers for fluorescence imaging. Now, place the sections in a culture dish with a cover slip bottom, and PBS to avoid drying the tissue. Also, use a glass weight to keep the tissue near the cover slip.Using the graphic user interface, set the image acquisition parameters for cars and missile fluorescence confocal imaging. Place the sample on the microscope stage, focus the sample, and capture the images. CARS'spectra range from 640 to 660 nanometers and there appears to be no overlap in spectra with nisel-tagged immunofluorescent marker, indicating that CARS signals can be used with immunofluorescent signals.Nisel was used to visualize the cell bodies of Mongolian gerbil and mouse brains, and CARS'imaging was used to visualize the myelin sheath, indicating that this technique could be used across species. Both sets of images show a section of the medial nucleus of the trapezoid body in the brain stem. The resolution of CARS is lower than with electron microscope and is on the order of several hundred nanometers.The images can be analyzed with standard image analysis software, such as ImageJ to quantify the parameters of interest, for example, myelin thickness or length.

coherent-anti-stokes-raman-spectroscopy-cars-application-for-imaging

Research

JoVE Journal

Neuroscience

A Rapid Approach to High-Resolution Fluorescence Imaging in Semi-Thick Brain Slices

A fundamental goal to both basic and clinical neuroscience is to better understand the identities, molecular makeup, and patterns of connectivity that are characteristic to neurons in both normal and diseased brain. Towards this, a great deal of effort has been placed on building high-resolution neuroanatomical maps1-3. With the expansion of molecular genetics and advances in light microscopy has come the ability to query not only neuronal morphologies, but also the molecular and cellular makeup of individual neurons and their associated networks4. Major advances in the ability to mark and manipulate neurons through transgenic and gene targeting technologies in the rodent now allow investigators to 'program' neuronal subsets at will5-6. Arguably, one of the most influential contributions to contemporary neuroscience has been the discovery and cloning of genes encoding fluorescent proteins (FPs) in marine invertebrates7-8, alongside their subsequent engineering to yield an ever-expanding toolbox of vital reporters9. Exploiting cell type-specific promoter activity to drive targeted FP expression in discrete neuronal populations now affords neuroanatomical investigation with genetic precision.
Engineering FP expression in neurons has vastly improved our understanding of brain structure and function. However, imaging individual neurons and their associated networks in deep brain tissues, or in three dimensions, has remained a challenge. Due to high lipid content, nervous tissue is rather opaque and exhibits auto fluorescence. These inherent biophysical properties make it difficult to visualize and image fluorescently labelled neurons at high resolution using standard epifluorescent or confocal microscopy beyond depths of tens of microns. To circumvent this challenge investigators often employ serial thin-section imaging and reconstruction methods10, or 2-photon laser scanning microscopy11. Current drawbacks to these approaches are the associated labor-intensive tissue preparation, or cost-prohibitive instrumentation respectively.
Here, we present a relatively rapid and simple method to visualize fluorescently labelled cells in fixed semi-thick mouse brain slices by optical clearing and imaging. In the attached protocol we describe the methods of: 1) fixing brain tissue in situ via intracardial perfusion, 2) dissection and removal of whole brain, 3) stationary brain embedding in agarose, 4) precision semi-thick slice preparation using new vibratome instrumentation, 5) clearing brain tissue through a glycerol gradient, and 6) mounting on glass slides for light microscopy and z-stack reconstruction (Figure 1).
For preparing brain slices we implemented a relatively new piece of instrumentation called the 'Compresstome' VF-200 (http://www.precisionary.com/products_vf200.html). This instrument is a semi-automated microtome equipped with a motorized advance and blade vibration system with features similar in function to other vibratomes. Unlike other vibratomes, the tissue to be sliced is mounted in an agarose plug within a stainless steel cylinder. The tissue is extruded at desired thicknesses from the cylinder, and cut by the forward advancing vibrating blade. The agarose plug/cylinder system allows for reproducible tissue mounting, alignment, and precision cutting. In our hands, the 'Compresstome' yields high quality tissue slices for electrophysiology, immunohistochemistry, and direct fixed-tissue mounting and imaging. Combined with optical clearing, here we demonstrate the preparation of semi-thick fixed brain slices for high-resolution fluorescent imaging.

Here we describe a rapid and simple method to image fluorescently labeled cells in semi-thick brain slices. By fixing, slicing, and optically clearing brain tissue we describe how standard epifluorescent or confocal imaging can be used to visualize individual cells and neuronal networks within intact nervous tissue.

A fundamental goal to both basic and clinical neuroscience is to better understand the identities, molecular makeup, and patterns of connectivity that are ...

High-resolution Live Imaging of Cell Behavior in the Developing Neuroepithelium

The embryonic spinal cord consists of cycling neural progenitor cells that give rise to a large percentage of the neuronal and glial cells of the central nervous system (CNS). Although much is known about the molecular mechanisms that pattern the spinal cord and elicit neuronal differentiation1, 2, we lack a deep understanding of these early events at the level of cell behavior. It is thus critical to study the behavior of neural progenitors in real time as they undergo neurogenesis.
In the past, real-time imaging of early embryonic tissue has been limited by cell/tissue viability in culture as well as the phototoxic effects of fluorescent imaging. Here we present a novel assay for imaging such tissue for long periods of time, utilizing a novel ex vivo slice culture protocol and wide-field fluorescence microscopy (Fig. 1). This approach achieves long-term time-lapse monitoring of chick embryonic spinal cord progenitor cells with high spatial and temporal resolution.
This assay may be modified to image a range of embryonic tissues3, 4 In addition to the observation of cellular and sub-cellular behaviors, the development of novel and highly sensitive reporters for gene activity (for example, Notch signaling5) makes this assay a powerful tool with which to understand how signaling regulates cell behavior during embryonic development.

Imaging embryonic tissue in real-time is challenging over long periods of time. Here we present an assay for monitoring cellular and sub-cellular changes in chick spinal cord for long periods with high spatial and temporal resolution. This technique can be adapted for other regions of the nervous system and developing embryo.

The embryonic spinal cord consists of cycling neural progenitor cells that give rise to a large percentage of the neuronal and glial cells of the central ...

Imaging Calcium Responses in GFP-tagged Neurons of Hypothalamic Mouse Brain Slices

Despite an enormous increase in our knowledge about the mechanisms underlying the encoding of information in the brain, a central question concerning the precise molecular steps as well as the activity of specific neurons in multi-functional nuclei of brain areas such as the hypothalamus remain. This problem includes identification of the molecular components involved in the regulation of various neurohormone signal transduction cascades. Elevations of intracellular Ca2+ play an important role in regulating the sensitivity of neurons, both at the level of signal transduction and at synaptic sites.
New tools have emerged to help identify neurons in the myriad of brain neurons by expressing green fluorescent protein (GFP) under the control of a particular promoter. To monitor both spatially and temporally stimulus-induced Ca2+ responses in GFP-tagged neurons, a non-green fluorescent Ca2+ indicator dye needs to be used. In addition, confocal microscopy is a favorite method of imaging individual neurons in tissue slices due to its ability to visualize neurons in distinct planes of depth within the tissue and to limit out-of-focus fluorescence. The ratiometric Ca2+ indicator fura-2 has been used in combination with GFP-tagged neurons1. However, the dye is excited by ultraviolet (UV) light. The cost of the laser and the limited optical penetration depth of UV light hindered its use in many laboratories. Moreover, GFP fluorescence may interfere with the fura-2 signals2. Therefore, we decided to use a red fluorescent Ca2+ indicator dye. The huge Stokes shift of fura-red permits multicolor analysis of the red fluorescence in combination with GFP using a single excitation wavelength. We had previously good results using fura-red in combination with GFP-tagged olfactory neurons3. The protocols for olfactory tissue slices seemed to work equally well in hypothalamic neurons4. Fura-red based Ca2+ imaging was also successfully combined with GFP-tagged pancreatic &beta;-cells and GFP-tagged receptors expressed in HEK cells5,6. A little quirk of fura-red is that its fluorescence intensity at 650 nm decreases once the indicator binds calcium7. Therefore, the fluorescence of resting neurons with low Ca2+ concentration has relatively high intensity. It should be noted, that other red Ca2+-indicator dyes exist or are currently being developed, that might give better or improved results in different neurons and brain areas.

In this protocol, we update recent progress in imaging Ca2+ signals of GFP-tagged neurons in brain tissue slices using a red fluorescent Ca2+ indicator dye.

Despite an enormous increase in our knowledge about the mechanisms underlying the encoding of information in the brain, a central question concerning the ...

Local Application of Drugs to Study Nicotinic Acetylcholine Receptor Function in Mouse Brain Slices

Tobacco use leads to numerous health problems, including cancer, heart disease, emphysema, and stroke. Addiction to cigarette smoking is a prevalent neuropsychiatric disorder that stems from the biophysical and cellular actions of nicotine on nicotinic acetylcholine receptors (nAChRs) throughout the central nervous system. Understanding the various nAChR subtypes that exist in brain areas relevant to nicotine addiction is a major priority.
Experiments that employ electrophysiology techniques such as whole-cell patch clamp or two-electrode voltage clamp recordings are useful for pharmacological characterization of nAChRs of interest. Cells expressing nAChRs, such as mammalian tissue culture cells or Xenopus laevis oocytes, are physically isolated and are therefore easily studied using the tools of modern pharmacology. Much progress has been made using these techniques, particularly when the target receptor was already known and ectopic expression was easily achieved. Often, however, it is necessary to study nAChRs in their native environment: in neurons within brain slices acutely harvested from laboratory mice or rats. For example, mice expressing "hypersensitive" nAChR subunits such as &alpha;4 L9&prime;A mice 1 and &alpha;6 L9&prime;S mice 2, allow for unambiguous identification of neurons based on their functional expression of a specific nAChR subunit. Although whole-cell patch clamp recordings from neurons in brain slices is routinely done by the skilled electrophysiologist, it is challenging to locally apply drugs such as acetylcholine or nicotine to the recorded cell within a brain slice. Dilution of drugs into the superfusate (bath application) is not rapidly reversible, and U-tube systems are not easily adapted to work with brain slices.
In this paper, we describe a method for rapidly applying nAChR-activating drugs to neurons recorded in adult mouse brain slices. Standard whole-cell recordings are made from neurons in slices, and a second micropipette filled with a drug of interest is maneuvered into position near the recorded cell. An injection of pressurized air or inert nitrogen into the drug-filled pipette causes a small amount of drug solution to be ejected from the pipette onto the recorded cell. Using this method, nAChR-mediated currents are able to be resolved with millisecond accuracy. Drug application times can easily be varied, and the drug-filled pipette can be retracted and replaced with a new pipette, allowing for concentration-response curves to be created for a single neuron. Although described in the context of nAChR neurobiology, this technique should be useful for studying many types of ligand-gated ion channels or receptors in neurons from brain slices.

In this paper, we describe a useful method to study ligand-gated ion channel function in neurons of acutely isolated brain slices. This method involves the use of a drug-filled micropipette for local application of drugs to neurons recorded using standard patch clamp techniques.

Tobacco use leads to numerous health problems, including cancer, heart disease, emphysema, and stroke. Addiction to cigarette smoking is a prevalent ...

In vivo Postnatal Electroporation and Time-lapse Imaging of Neuroblast Migration in Mouse Acute Brain Slices

The subventricular zone (SVZ) is one of the main neurogenic niches in the postnatal brain. Here, neural progenitors proliferate and give rise to neuroblasts able to move along the rostral migratory stream (RMS) towards the olfactory bulb (OB). This long-distance migration is required for the subsequent maturation of newborn neurons in the OB, but the molecular mechanisms regulating this process are still unclear. Investigating the signaling pathways controlling neuroblast motility may not only help understand a fundamental step in neurogenesis, but also have therapeutic regenerative potential, given the ability of these neuroblasts to target brain sites affected by injury, stroke, or degeneration.
In this manuscript we describe a detailed protocol for in vivo postnatal electroporation and subsequent time-lapse imaging of neuroblast migration in the mouse RMS. Postnatal electroporation can efficiently transfect SVZ progenitor cells, which in turn generate neuroblasts migrating along the RMS. Using confocal spinning disk time-lapse microscopy on acute brain slice cultures, neuroblast migration can be monitored in an environment closely resembling the in vivo condition. Moreover, neuroblast motility can be tracked and quantitatively analyzed. As an example, we describe how to use in vivo postnatal electroporation of a GFP-expressing plasmid to label and visualize neuroblasts migrating along the RMS. Electroporation of shRNA or CRE recombinase-expressing plasmids in conditional knockout mice employing the LoxP system can also be used to target genes of interest. Pharmacological manipulation of acute brain slice cultures can be performed to investigate the role of different signaling molecules in neuroblast migration. By coupling in vivo electroporation with time-lapse imaging, we hope to understand the molecular mechanisms controlling neuroblast motility and contribute to the development of novel approaches to promote brain repair.

In vivo Postnatal Electroporation and Time-lapse Imaging of Neuroblast Migration in Mouse Acute Brain Slices

Neuroblast migration is a fundamental event in postnatal neurogenesis. We describe a protocol for efficient labeling of neuroblasts by in vivo postnatal electroporation and subsequent visualization of their migration using time-lapse imaging of acute brain slices. We include a description for the quantitative analysis of neuroblast dynamics by video tracking.

The subventricular zone (SVZ) is one of the main neurogenic niches in the postnatal brain. Here, neural progenitors proliferate and give rise to ...

Paired Whole Cell Recordings in Organotypic Hippocampal Slices

Pair recordings involve simultaneous whole cell patch clamp recordings from two synaptically connected neurons, enabling not only direct electrophysiological characterization of the synaptic connections between individual neurons, but also pharmacological manipulation of either the presynaptic or the postsynaptic neuron. When carried out in organotypic hippocampal slice cultures, the probability that two neurons are synaptically connected is significantly increased. This preparation readily enables identification of cell types, and the neurons maintain their morphology and properties of synaptic function similar to that in native brain tissue. A major advantage of paired whole cell recordings is the highly precise information it can provide on the properties of synaptic transmission and plasticity that are not possible with other more crude techniques utilizing extracellular axonal stimulation. Paired whole cell recordings are often perceived as too challenging to perform. While there are challenging aspects to this technique, paired recordings can be performed by anyone trained in whole cell patch clamping provided specific hardware and methodological criteria are followed. The probability of attaining synaptically connected paired recordings significantly increases with healthy organotypic slices and stable micromanipulation allowing independent attainment of pre- and postsynaptic whole cell recordings. While CA3-CA3 pyramidal cell pairs are most widely used in the organotypic slice hippocampal preparation, this technique has also been successful in CA3-CA1 pairs and can be adapted to any neurons that are synaptically connected in the same slice preparation. In this manuscript we provide the detailed methodology and requirements for establishing this technique in any laboratory equipped for electrophysiology.

Pair recordings are simultaneous whole cell patch clamp recordings from two synaptically connected neurons, enabling precise electrophysiological and pharmacological characterization of the synapses between individual neurons. Here we describe the detailed methodology and requirements for establishing this technique in organotypic hippocampal slice cultures in any laboratory equipped for electrophysiology.

Pair recordings involve simultaneous whole cell patch clamp recordings from two synaptically connected neurons, enabling not only direct ...

Ex Vivo Optogenetic Dissection of Fear Circuits in Brain Slices

Optogenetic approaches are now widely used to study the function of neural populations and circuits by combining targeted expression of light-activated proteins and subsequent manipulation of neural activity by light. Channelrhodopsins (ChRs) are light-gated cation-channels and when fused to a fluorescent protein their expression allows for visualization and concurrent activation of specific cell types and their axonal projections in defined areas of the brain. Via stereotactic injection of viral vectors, ChR fusion proteins can be constitutively or conditionally expressed in specific cells of a defined brain region, and their axonal projections can subsequently be studied anatomically and functionally via ex vivo optogenetic activation in brain slices. This is of particular importance when aiming to understand synaptic properties of connections that could not be addressed with conventional electrical stimulation approaches, or in identifying novel afferent and efferent connectivity that was previously poorly understood. Here, a few examples illustrate how this technique can be applied to investigate these questions to elucidating fear-related circuits in the amygdala. The amygdala is a key region for acquisition and expression of fear, and storage of fear and emotional memories. Many lines of evidence suggest that the medial prefrontal cortex (mPFC) participates in different aspects of fear acquisition and extinction, but its precise connectivity with the amygdala is just starting to be understood. First, it is shown how ex vivo optogenetic activation can be used to study aspects of synaptic communication between mPFC afferents and target cells in the basolateral amygdala (BLA). Furthermore, it is illustrated how this ex vivo optogenetic approach can be applied to assess novel connectivity patterns using a group of GABAergic neurons in the amygdala, the paracapsular intercalated cell cluster (mpITC), as an example.

Ex Vivo Optogenetic Dissection of Fear Circuits in Brain Slices

Optogenetic approaches are widely used to manipulate neural activity and assess the consequences for brain function. Here, a technique is outlined that&#160;upon in vivo expression of the optical activator Channelrhodopsin, allows for ex vivo analysis of synaptic properties of specific long range and local neural connections in fear-related circuits.

Optogenetic approaches are now widely used to study the function of neural populations and circuits by combining targeted expression of light-activated ...

Application of Automated Image-guided Patch Clamp for the Study of Neurons in Brain Slices

Whole-cell patch clamp is the gold-standard method to measure the electrical properties of single cells. However, the in vitro patch clamp remains a challenging and low-throughput technique due to its complexity and high reliance on user operation and control. This manuscript demonstrates an image-guided automatic patch clamp system for in vitro whole-cell patch clamp experiments in acute brain slices. Our system implements a computer vision-based algorithm to detect fluorescently labeled cells and to target them for fully automatic patching using a micromanipulator and internal pipette pressure control. The entire process is highly automated, with minimal requirements for human intervention. Real-time experimental information, including electrical resistance and internal pipette pressure, are documented electronically for future analysis and for optimization to different cell types. Although our system is described in the context of acute brain slice recordings, it can also be applied to the automated image-guided patch clamp of dissociated neurons, organotypic slice cultures, and other non-neuronal cell types.

This protocol describes how to conduct automatic image-guided patch-clamp experiments using a system recently developed for standard in vitro electrophysiology equipment.

Whole-cell patch clamp is the gold-standard method to measure the electrical properties of single cells. However, the in vitro patch clamp remains a ...

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 ...

Two-photon Calcium Imaging in Neuronal Dendrites in Brain Slices

Calcium (Ca2+) imaging is a powerful tool to investigate the spatiotemporal dynamics of intracellular Ca2+ signals in neuronal dendrites. Ca2+ fluctuations can occur through a variety of membrane and intracellular mechanisms and play a crucial role in the induction of synaptic plasticity and regulation of dendritic excitability. Hence, the ability to record different types of Ca2+ signals in dendritic branches is valuable for groups studying how dendrites integrate information. The advent of two-photon microscopy has made such studies significantly easier by solving the problems inherent to imaging in live tissue, such as light scattering and photodamage. Moreover, through combination of conventional electrophysiological techniques with two-photon Ca2+ imaging, it is possible to investigate local Ca2+ fluctuations in neuronal dendrites in parallel with recordings of synaptic activity in soma. Here, we describe how to use this method to study the dynamics of local Ca2+ transients (CaTs) in dendrites of GABAergic inhibitory interneurons. The method can be also applied to studying dendritic Ca2+ signaling in different neuronal types in acute brain slices.

We present a method combining whole-cell patch-clamp recordings and two-photon imaging to record Ca2+ transients in neuronal dendrites in acute brain slices.