We would like to acknowledge the significant contribution Dr. Shiwei Huang (Australian National University) in validating the method. Furthermore, we would like to thank Ms. Kasia Pietrajtis for helpful comments regarding Golgi cells and Mr. Vitaly Lerner for the cortex experimental data. This work was supported by PITN-GA-2009-238686 (CEREBNET), FP7-ICT (REALNET), ELSC and ISF.

All experimental procedures described in this protocol were approved by the Hebrew University&#39;s Animal Care and Use Committee.
1. Preparing the Solutions and Tools for Slicing
<ol>
	<li>Prepare 1 L of standard physiological solution (SPS) containing the ions described in Table 1.
	<ol>
		<li>Prepare a stock solution containing the salts at 10 times the final concentration in advance in a storage glass bottle filled with 1,000 ml of deionized water (conductance of 0.055 &#181;S/cm). Add salts (NaCl, KCl, KH2PO4, and MgSO4), and stir until completely dissolved. Store the stock solution in 4 &#176;C.</li>
		<li>Make the final SPS solution on the day of the experiment. Add 100 ml of the stock solution to 700 ml of purified water, dissolve the glucose (3.6 g) and NaHCO3 (2.18 g) using magnetic stir bar and then add purified water up to 1 L.</li>
		<li>Equilibrate the solution by gassing it with 95% O2 / 5% CO2 for ~20 min. After this, add 2 ml of 1 M CaCl2 solution.</li>
	</ol>
	</li>
	<li>Assemble the following tools (Figure 1).
	<ol>
		<li>Prepare big scissors or other tool for decapitation, small surgical scissors for opening the skull, fine tip forceps for lifting the skull to expose the brain, scalpel with blade for dissecting the desired part of the brain to be sliced and a small spatula for manipulating the dissected brain parts.</li>
		<li>In addition, prepare small pieces of filter paper for removing excess liquid from the brain, two small Petri dishes for the brain to be dissected in two glass 500 ml beakers for containing warmed purified water and SPS, and cyanoacrylate glue for gluing the brain to the slicing stage.</li>
		<li>Prepare a small brush for handling the slices during the slicing and a wide-mouthed glass Pasteur pipette for moving the slices from the slicing bath to the recovery chamber. Disinfect the tools to prevent bacteria growth in the warm slice baths. Furthermore, use clean laboratory gloves.</li>
	</ol>
	</li>
	<li>Prepare a submerged slice recovery chamber such as described by Gibb and Edwards15. Continuously gas the SPS in it with 95% O2 / 5% CO2 and keep at 36 &#176;C. Make sure that the gassing does not result in small bubbles trapped in the bath that could damage slices.</li>
	<li>Warm ~300 ml of the SPS to 36 &#176;C on a heater plate with magnetic stirrer or in a water bath. If a heater plate is used, take care to prevent the solution from overheating, which may result in ion precipitation. In case it happens, warm fresh SPS instead of cooling the old one.</li>
	<li>Bring ~500 ml of purified water to boil using an electric kettle and, in a beaker, combine 300 ml of it with cool water to obtain slightly warmer water than the slicing temperature. Use this warmed purified water during the decapitation and use the remaining of the boiled water later for maintaining the physiological temperature of the slicing bath.</li>
	<li>Anaesthetize the mouse by injecting 0.1 ml of pentobarbital (60 mg/ml) intraperitoneally. After a few minutes check that the animal does not respond to strong toe or tail pinches to ascertain the lack of sensation.</li>
</ol>
2. Dissecting the Brain
<ol>
	<li>Decapitate the mouse quickly by cutting the neck with the big scissors near the back of the skull, and let the head fall into the beaker with warmed purified water to rinse off excess blood.</li>
	<li>Expose the foramen magnum in the skull under the neck muscles and skin, possibly removing more of the neck with the small scissors.</li>
	<li>Pull the skin on the top of the skull to be able to clearly see the skull sutures in order to guide opening of the skull.</li>
	<li>Cut the skull open by inserting the lower tip of the small scissors through the foramen magnum and immediately turning them towards the lateral side. Gently cut along the lateral edge of the parietal bone up to a location behind the eyes and the frontoparietal suture; then, turn towards the center of the skull and cut across the midline to the other side of the skull (see green dashed line in Figure 2A).</li>
	<li>Using fine tip forceps, lift the skull from the frontoparietal corner and pull it diagonally up and sidewards to expose the brain (see yellow dashed arrow in Figure 2A). Make sure that the skull is not attached to any bone or skin of the head, so that the brain will stay in place when the skull is lifted. In case that the brain is moving with the skull, use the small scissors to remove any connective tissue between the skull and the brain.</li>
	<li>When the brain is exposed, do not allow the brain to be dry. Thus, perform the next steps while keeping the skull and the brain in a Petri dish filled with warmed, gassed SPS.</li>
	<li>Detach the part of the brain used for experiment from the rest of the brain using a scalpel and a spatula. In case of using the cerebellum, detach from the forebrain by a single cut through the midbrain and pons (along red lines in Figures 2B-D) and move it to a small Petri dish that contains fresh, gassed SPS.</li>
	<li>Remove the brainstem to form a straight and wide base for gluing the brain to cutting stage when slicing the cerebellum in horizontal plane. Briefly place the cerebellum on a wet piece of filter paper so that the side that was cut from the forebrain is facing down.
	<ol>
		<li>Cut the brainstem with a scalpel to form the base (as indicated with the blue line in Figure 2B), and return the cerebellum to the SPS. When other planes of cutting are needed, trim the cerebellum block accordingly (blue lines in Figures 2C &#38; D).</li>
	</ol>
	</li>
</ol>
3. Slicing the Brain
<ol>
	<li>Prepare the cutting stage by ascertaining that it is dry, before applying a small drop of superglue in the middle of the stage.</li>
	<li>Lift the brain block from the SPS using a spatula with correct side up, and remove any excess liquid from the brain using small pieces of filter paper. Then, with a single movement, slide the brain from the spatula onto the drop of glue on the stage.</li>
	<li>To prevent the brain from drying and the glue from running up on the sides of the tissue, apply a few drops of SPS with a Pasteur pipette and place the cutting stage in the slicing chamber. Align the brain block so that the regions of interest (e.g., cerebellar cortex) are facing the blade and thus will be subjected to least amount of mechanical pressure before being sliced.</li>
	<li>Cut each slice according to the manufacturer&#8217;s instructions while constantly gassing the SPS in the cutting chamber as well as maintaining the temperature at 34-37 &#176;C. Keep the temperature of the cutting chamber at this range by filling the external chamber of the slicer with warmed purified water and replacing the water whenever the temperature falls too low. 
	NOTE: The slicing parameters must be experimentally found for each type of tissue and neurons that are being examined. In case of the Campden SMZ 700 slicer with ceramic blades and cerebellar Golgi cells, use 0.75 mm vibration amplitude at 65 Hz and advancing speed of 0.05 mm/sec; for cerebellar nuclear neurons higher amplitude and frequency (1 mm and 90 Hz, respectively) and slower advance speed (0.01-0.02 mm/sec) are recommended. For both Golgi and cerebellar nuclear neurons, slice thickness should be 300 &#181;m.</li>
	<li>During the slicing, do not allow the slices to fold on themselves. Prevent this by gently supporting them with a soft brush, preferably touching the slice only in regions that are not of interest for the experiment. Take care to prevent the brush from touching the vibratome blade; especially in case of the ceramic blades, even a light contact can damage the blade.</li>
	<li>Move each slice from the slicing chamber to a recovery/holding chamber using a wide-mouthed, fire-polished glass Pasteur pipette.</li>
	<li>Let the slices rest in the chamber for at least 1 hr before starting the experiment. This allows for degradation of damaged or dying tissue and cells and thus results in a cleaner slice surface. During the first hour, keep the temperature of the SPS in the chamber in the range of 34-36 &#176;C; ensure that the slices are not touched by air bubbles that can damage the slices or make them float.</li>
</ol>
4. Experiment
<ol>
	<li>After 1 hr, let the recovery chamber temperature cool down to RT (17-25 &#176;C). 
	NOTE: This might prolong the time period during which the slices can be used by slowing down the growth of bacteria as well as cellular metabolism. This period depends on the brain region and cell type. For example, certain types of Golgi cells can be found to be healthy in slices 8 hr after cutting whereas other types last only 6 hr.</li>
	<li>After 1 hr has passed from the slicing, use the slices for various electrophysiological experiments.</li>
</ol>

<ol>
	<li>Skrede, K., Westgaard, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+transverse+hippocampal+slice:+a+well-defined+cortical+structure+maintained+in+vitro.">The transverse hippocampal slice: a well-defined cortical structure maintained in vitro.</a> Brain Research. 35, 589-593 (1971).</li><li>Aghajanian, G., Rasmussen, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intracellular+studies+in+the+facial+nucleus+illustrating+a+simple+new+method+for+obtaining+viable+motoneurons+in+adult+rat+brain+slices.">Intracellular studies in the facial nucleus illustrating a simple new method for obtaining viable motoneurons in adult rat brain slices.</a> Synapse. 3, 331-338 (1989).</li><li>Gueritaud, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrical+activity+of+rat+ocular+motoneurons+recorded+in+vitro.">Electrical activity of rat ocular motoneurons recorded in vitro.</a> Neuroscience. 24, 837-852 (1988).</li><li>Lipton, 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=Making+the+best+of+brain+slices:+comparing+preparative+methods.">Making the best of brain slices: comparing preparative methods.</a> Journal of Neuroscience Methods. 59, 151-156 (1995).</li><li>Richerson, G., Messer, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+composition+of+experimental+solutions+on+neuronal+survival+during+rat+brain+slicing.">Effect of composition of experimental solutions on neuronal survival during rat brain slicing.</a> Experimental Neurology. 131, 133-143 (1995).</li><li>Brahma, B., Forman, R., Stewart, E., Nicholson, C., Rice, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ascorbate+inhibits+edema+in+brain+slices.">Ascorbate inhibits edema in brain slices.</a> Journal of Neurochemistry. 74, 1263-1270 (2000).</li><li>Moyer, J. R., Brown, T. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Patch-clamp+techniques+applied+to+brain+slices.+In:+Patch-clamp+analysis:+advanced+techniques.">Patch-clamp techniques applied to brain slices. In: Patch-clamp analysis: advanced techniques.</a> Springer. , 135-193 (2002).</li><li>Ye, J. H., Zhang, J., Xiao, C., Kong, J. Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Patch-clamp+studies+in+the+CNS+illustrate+a+simple+new+method+for+obtaining+viable+neurons+in+rat+brain+slices:+glycerol+replacement+of+NaCl+protects+CNS+neurons.">Patch-clamp studies in the CNS illustrate a simple new method for obtaining viable neurons in rat brain slices: glycerol replacement of NaCl protects CNS neurons.</a> J. Neuroscience Methods. 156, 251-259 (2006).</li><li>Bischofberger, J., Engel, D., Li, L., Geiger, J., Jonas, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Patch-clamp+recording+from+mossy+fiber+terminals+in+hippocampal+slices.">Patch-clamp recording from mossy fiber terminals in hippocampal slices.</a> Nature Protocols. 1, 2075-2081 (2006).</li><li>Zhao, S., 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=Cell+type&#8211;specific+channelrhodopsin-2+transgenic+mice+for+optogenetic+dissection+of+neural+circuitry+function.">Cell type&#8211;specific channelrhodopsin-2 transgenic mice for optogenetic dissection of neural circuitry function.</a> Nature Methods. 8, 745-752 (2011).</li><li>Huang, S., Uusisaari, M. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physiological+temperature+during+brain+slicing+enhances+the+quality+of+acute+slice+preparations.">Physiological temperature during brain slicing enhances the quality of acute slice preparations.</a> Front. Cell. Neurosci. 7, (2013).</li><li>Ohe, G. C., Darian-Smith, C., Garner, C. C., Heller, H. C. <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 Journal of Neuroscience. 26 (41), 10590-10598 (2006).</li><li>Voets, 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=The+principle+of+temperature-dependent+gating+in+cold-+and+heat-sensitive+TRP+channels.">The principle of temperature-dependent gating in cold- and heat-sensitive TRP channels.</a> Nature. 430, 748-754 (2004).</li><li>Coulter, D. A., Huguenard, J. R., Prince, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calcium+currents+in+rat+thalamocortical+relay+neurones:+kinetic+properties+of+the+transient,+low-threshold+current.">Calcium currents in rat thalamocortical relay neurones: kinetic properties of the transient, low-threshold current.</a> The Journal of Physiology. 414, 587-604 (1998).</li><li>Gibb, A. J., Edward, F. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Patch+clamp+recording+from+cells+in+slice+tissues.">Patch clamp recording from cells in slice tissues.</a> Microelectrode Techniques: the Plymouth workshop handbook. , (1994).</li><li>Lefler, Y., Yarom, Y., Uusisaari, M. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebellar+Inhibitory+Input+to+the+Inferior+Olive+Decreases+Electrical+Coupling+and+Blocks+Subthreshold+Oscillations.">Cerebellar Inhibitory Input to the Inferior Olive Decreases Electrical Coupling and Blocks Subthreshold Oscillations.</a> Neuron. 81 (6), 1389-1400 (2014).</li><li>Bourne, J. N., Kirov, S. A., Sorra, K. E., Harris, K. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Warmer+preparation+of+hippocampal+slices+prevents+synapse+proliferation+that+might+obscure+LTP-related+structural+plasticity.">Warmer preparation of hippocampal slices prevents synapse proliferation that might obscure LTP-related structural plasticity.</a> Neuropharmacology. 52, 55-59 (2007).</li><li>Kirov, S. A., Sorra, K. E., Harris, K. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Slices+have+more+synapses+than+perfusion-fixed+hippocampus+from+both+young+and+mature+rats.">Slices have more synapses than perfusion-fixed hippocampus from both young and mature rats.</a> J. Neurosci. 19, 2876-2886 (1999).</li><li>Kirov, S. A., Petrak, L. J., Fiala, J. C., Harris, K. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dendritic+spines+disappear+with+chilling+but+proliferate+excessively+upon+rewarming+of+mature+hippocampus.">Dendritic spines disappear with chilling but proliferate excessively upon rewarming of mature hippocampus.</a> Neuroscience. 127, 69-80 (2004).</li><li>Tanaka, Y., Tanaka, Y., Furuta, T., Yanagawa, Y., Kaneko, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effects+of+cutting+solutions+on+the+viability+of+GABAergic+interneurons+in+cerebral+cortical+slices+of+adult+mice.">The effects of cutting solutions on the viability of GABAergic interneurons in cerebral cortical slices of adult mice.</a> J. Neurosci. Methods. 171, 181-125 (2008).</li></ol>

The authors declare that they have no competing financial interests.

We demonstrate a method for preparing acute brain slices from mice in physiological instead of ice-cold temperature.
It has been shown11 that the quality of slices obtained in warm conditions is superior when compared with those prepared with cold conditions, provided that the slicer blade has minimal vertical vibration. Slicing in physiological temperature may prevent physiological artifacts caused by the low temperature, such as those related to changes in metabolic processes...

The aim of the presented method is to get high-quality acute brain slices for in vitro electrophysiological experiments, especially when using adult or even old animals.
The acute brain slicing method, as described by Skrede and Westgaard1 in two elegant sentences, has become one of the foundations of modern neuroscience research and is employed in innumerable variations worldwide. The quality of the slices is reflected in number of living neurons per slice, the period of time during which the cells keep their electrophysiological and morphological properties as well as in the integrity of the tissue. Moreover, the maximal duration for stable recordings depends on the quality of the slices. Thus, along the decades, the original slicing method has been further developed by individual research groups to enhance slice recovery after cutting2-10, often by complex modifications of the composition of cutting or recovery solutions (such as adding ascorbate, thiourea or even H2O2) as well as intra-cardiac pre-perfusion of the animal with cooled physiological solutions.
As has been recently shown11, physiological temperature during slicing seems to be more beneficial than cooling to neuronal health; the improvement is most striking when working with adult (2-8 month) rodents. Avoiding dramatic temperature changes prevents artifacts due to temperature-dependent processes in the cells, such as plasticity13 and ion-channels kinetics13,14. Such changes could influence membrane voltage and intracellular calcium signaling, spike threshold, and spike shape.
The &#8220;hot&#8221; acute slice preparation method presented here is a general procedure for obtaining high-quality acute brain slices from any brain region, including the cerebellum, the cortex and hippocampus, brainstem nuclei16 as well as the olfactory bulb, both in rats and mice.
Notably, the physiological temperature slicing procedure requires that the cutting blade vibrates nearly perfectly horizontally and is without any structural defects. Such precision might not be attainable with older slicer models; in such cases, we recommend performing the slice preparation in freezing-cold conditions as the low temperature seems to make the tissue more resistant to mechanical damage, even if at the cost of metabolic aberrations.

<table><tbody><tr><td>Pentobarbital</td><td>CTS</td><td>170066</td><td>Concentration: 60 mg/ml in physiological saline.</td></tr><tr><td>Big scissors&amp;nbsp;</td><td>FST</td><td>14001-16</td><td>Any large scissors or a guillotine with sufficiently sharp edges can be used for decapitation&amp;nbsp;</td></tr><tr><td>Iris scissors&amp;nbsp;</td><td>Prestige medical</td><td>48,148</td><td>Any fine tip scissors can be used, provided the scissor blades are not longer than 1.5&amp;#8211;2 cm</td></tr><tr><td>Fine tip forceps&amp;nbsp;</td><td>FST</td><td>11254-20</td><td></td></tr><tr><td>Scalpel&amp;nbsp;</td><td>FST</td><td>91003-12</td><td></td></tr><tr><td>Scalpel blade #11</td><td>FST</td><td>10011-00</td><td></td></tr><tr><td>Small spatula&amp;nbsp;</td><td>Fisher&amp;nbsp;</td><td>2350</td><td></td></tr><tr><td>Filter paper</td><td></td><td></td><td>Any laboratory brand can be used.</td></tr><tr><td>Petri dishes</td><td>Duroplan</td><td>Z231509-1</td><td></td></tr><tr><td>Glass beakers&amp;nbsp;</td><td>SCHOT</td><td>10022846</td><td></td></tr><tr><td>Pasteur pipette&amp;nbsp;</td><td>Maple Leaf Brand</td><td>14672-029</td><td></td></tr><tr><td>Super glue&amp;nbsp;</td><td>LOCTITE</td><td>4091361/1</td><td></td></tr><tr><td>Slicer</td><td>Campden</td><td>7000-smz</td><td></td></tr><tr><td>Ceramic slicing blade</td><td>Campden</td><td>7550-1-C</td><td></td></tr><tr><td>Magnetic heater/stirrer</td><td></td><td></td><td>For heating up the SPS for the procedure</td></tr><tr><td>Electric kettle</td><td></td><td></td><td>For heating up water for temperature control</td></tr><tr><td>Slice recovery chamber + heating unit</td><td>Warner instruments</td><td>&amp;nbsp;BSC-HT +&amp;nbsp; BSC-BUW</td><td>Home-built models may also be used.</td></tr><tr><td>Thermometer</td><td></td><td></td><td>For monitoring SPS temperature during dissection and slicing</td></tr></tbody></table>

slice it hot: acute adult brain slicing in physiological temperature

Here we present a protocol for preparation of acute brain slices. This procedure is a critical element for electrophysiological patch-clamp experiments that largely determines the quality of results. It has been shown that omitting the cooling step during cutting procedure is beneficial in obtaining healthy slices and cells, especially when dealing with highly myelinated brain structures from mature animals. Even though the precise mechanism whereby elevated temperature supports neural health can only be speculated upon, it stands to reason that, whenever possible, the temperature in which the slicing is performed should be close to physiological conditions to prevent temperature related artifacts. Another important advantage of this method is the simplicity of the procedure and therefore the short preparation time. In the demonstrated method adult mice are used but the same procedure can be applied with younger mice as well as rats. Also, the following patch clamp experiment is performed on horizontal cerebellar slices, but the same procedure can also be used in other planes as well as other posterior areas of the brain.

Slices prepared in the described manner can be used for various electrophysiological and optogenetic experiments. In Figure 3A and 3C, we show a representative example of a horizontal cerebellar slice and a coronal cerebral cortical slice, respectively, viewed under differential interference (DIC) optics. In the cerebellar slice, several types of cerebellar neurons can be easily recognized by their location and cell body shape, allowing targeted electrophysiological recordings. In <stron...

Watch this Scientific Journal Video about Slice It Hot: Acute Adult Brain Slicing in Physiological Temperature at JoVE.com

Slice It Hot: Acute Adult Brain Slicing in Physiological Temperature

In this paper we show a method for preparing acute brain slices in physiological temperature, using a conventional physiological solution without special modifications for the cutting (such as adding sucrose) and without intracardial perfusion of the animal before slice preparation.

Here we present a protocol for preparation of acute brain slices. This procedure is a critical element for electrophysiological patch-clamp experiments ...

slice-it-hot-acute-adult-brain-slicing-in-physiological-temperature

Research

JoVE Journal

Neuroscience

26.4K Views.  Hebrew University of Jerusalem. In this paper we show a method for preparing acute brain slices in physiological temperature, using a conventional physiological solution without special modifications for the cutting (such as adding sucrose) and without intracardial perfusion of the animal before slice preparation.

Video: Slice It Hot: Acute Adult Brain Slicing in Physiological Temperature

Preparation of Acute Brain Slices Using an Optimized N-Methyl-D-glucamine Protective Recovery Method

This protocol is a practical guide to the N-methyl-D-glucamine (NMDG) protective recovery method of brain slice preparation. Numerous recent studies have validated the utility of this method for enhancing neuronal preservation and overall brain slice viability. The implementation of this technique by early adopters has facilitated detailed investigations into brain function using diverse experimental applications and spanning a wide range of animal ages, brain regions, and cell types. Steps are outlined for carrying out the protective recovery brain slice technique using an optimized NMDG artificial cerebrospinal fluid (aCSF) media formulation and enhanced procedure to reliably obtain healthy brain slices for patch clamp electrophysiology. With this updated approach, a substantial improvement is observed in the speed and reliability of gigaohm seal formation during targeted patch clamp recording experiments while maintaining excellent neuronal preservation, thereby facilitating challenging experimental applications. Representative results are provided from multi-neuron patch clamp recording experiments to assay synaptic connectivity in neocortical brain slices prepared from young adult transgenic mice and mature adult human neurosurgical specimens. Furthermore, the optimized NMDG protective recovery method of brain slicing is compatible with both juvenile and adult animals, thus resolving a limitation of the original methodology. In summary, a single media formulation and brain slicing procedure can be implemented across various species and ages to achieve excellent viability and tissue preservation.

Preparation of Acute Brain Slices Using an Optimized N-Methyl-D-glucamine Protective Recovery Method

This protocol demonstrates the implementation of an optimized N-methyl-D-glucamine (NMDG) protective recovery method of brain slice preparation. A single media formulation is used to reliably obtain healthy brain slices from animals of any age and for diverse experimental applications.

This protocol is a practical guide to the N-methyl-D-glucamine (NMDG) protective recovery method of brain slice preparation. Numerous recent studies have ...

Subcellular Patch-clamp Recordings from the Somatodendritic Domain of Nigral Dopamine Neurons

Dendrites of dopaminergic neurons receive and convey synaptic input, support action potential back-propagation and neurotransmitter release. Understanding these fundamental functions will shed light on the information transfer in these neurons. Dendritic patch-clamp recordings provide the possibility to directly examine the electrical properties of dendrites and underlying voltage-gated ion channels. However, these fine structures are not easily accessible to patch pipettes because of their small diameter. This report describes a step-by-step procedure to collect stable and reliable recordings from the dendrites of dopaminergic neurons in acute slices. Electrophysiological measurements are combined with post hoc recovery of cell morphology. Successful experiments rely on improved preparation of slices, solutions and pipettes, adequate adjustment of the optics and stability of the pipette in contact with the recorded structure. Standard principles of somatic patch-clamp recording are applied to dendrites but with a gentler approach of the pipette. These versatile techniques can be implemented to address various questions concerning the excitable properties of dendrites.

Subcellular patch-clamp recordings offer the possibility to investigate the functional properties of dendrites. However these fine structures are not easily accessible due to their small diameter. The protocol described here aims to facilitate the collection of stable and reliable recordings from the dendrites of dopamine neurons in slices in vitro.

Dendrites of dopaminergic neurons receive and convey synaptic input, support action potential back-propagation and neurotransmitter release. Understanding ...

Stereotactic Atlas-Guided Laser Capture Microdissection of Brain Regions Affected by Traumatic Injury

The ability to isolate specific brain regions of interest can be impeded in tissue disassociation techniques that do not preserve their spatial distribution. Such techniques also potentially skew gene expression analysis because the process itself can alter expression patterns in individual cells. Here we describe a laser capture microdissection (LCM) method to selectively collect specific brain regions affected by traumatic brain injury (TBI) by using a modified Nissl (cresyl violet) staining protocol and the guidance of a rat brain atlas. LCM provides access to brain regions in their native positions and the ability to use anatomical landmarks for identification of each specific region. To this end, LCM has been used previously to examine brain region specific gene expression in TBI. This protocol allows examination of TBI-induced alterations in gene and microRNA expression in distinct brain areas within the same animal. The principles of this protocol can be amended and applied to a wide range of studies examining genomic expression in other disease and/or animal models.

We describe the use of laser capture microdissection to obtain samples of distinct cell populations from different brain regions for gene and microRNA analysis. This technique allows the study of differential effects of traumatic brain injury in specific regions of the rat brain.

The ability to isolate specific brain regions of interest can be impeded in tissue disassociation techniques that do not preserve their spatial ...

An Alternative Approach to Study Primary Events in Neurodegeneration Using Ex Vivo Rat Brain Slices

Despite&#160;numerous studies that attempt to develop reliable animal models&#160;which reflecting the primary processes underlying neurodegeneration, very few have been widely accepted. Here, we propose&#160;a new procedure&#160;adapted from the well-known ex vivo brain slice technique, which offers a closer in vivo-like scenario than in vitro preparations, for investigating the early events triggering cell degeneration, as observed in Alzheimer&#39;s disease (AD). This variation consists of simple and easily reproducible steps, which enable preservation of the anatomical cytoarchitecture of the selected brain region and its local functionality in a physiological milieu. Different anatomical areas can be obtained from the same brain, providing the opportunity to perform multiple experiments with the treatments in question in a site-, dose-, and time-dependent manner. Potential limitations&#160;which could affect the outcomes related to this methodology are related to the conservation of the tissue, i.e., the maintenance of its anatomical integrity during the slicing and incubation steps and the section thickness, which can influence the biochemical and immunohistochemical analysis. This approach can be employed for different purposes, such as exploring molecular mechanisms involved in physiological or pathological conditions, drug screening, or dose-response assays. Finally, this protocol could also reduce the number of animals employed in behavioral studies. The application reported here has been recently described and tested for the first time on ex vivo rat brain slices containing the basal forebrain (BF), which is one of the cerebral regions primarily affected in AD. Specifically, it has been demonstrated that the administration of a toxic peptide derived from the C-terminus of acetylcholinesterase (AChE) could prompt an AD-like profile, triggering, along the antero-posterior axis of the BF, a differential expression of proteins altered in AD, such as the alpha7 nicotinic receptor (&#945;7-nAChR), phosphorylated Tau (p-Tau), and amyloid beta (A&#946;).

An Alternative Approach to Study Primary Events in Neurodegeneration Using Ex Vivo Rat Brain Slices

We present a method which can&#160;provide further insights into the early events underlying neurodegeneration and based on the established ex-vivo brain technique, combining the advantages of in vivo and in vitro experiments. Moreover, it represents a unique opportunity for direct comparison of treated and untreated group in the same anatomical plane.

Despite&#160;numerous studies that attempt to develop reliable animal models&#160;which reflecting the primary processes underlying neurodegeneration, ...

Two-photon Imaging of Microglial Processes' Attraction Toward ATP or Serotonin in Acute Brain Slices

Microglial cells are resident innate immune cells of the brain that constantly scan their environment with their long processes and, upon disruption of homeostasis, undergo rapid morphological changes. For example, a laser lesion induces in a few minutes an oriented growth of microglial processes, also called &#34;directional motility&#34;, toward the site of injury. A similar effect can be obtained by delivering locally ATP or serotonin (5-hydroxytryptamine [5-HT]). In this article, we describe a protocol to induce a directional growth of microglial processes toward a local application of ATP or 5-HT in acute brain slices of young and adult mice and to image this attraction over time by multiphoton microscopy. A simple method of quantification with free and open-source image analysis software is proposed. A challenge that still characterizes acute brain slices is the limited time, decreasing with age, during which the cells remain in a physiological state. This protocol, thus, highlights some technical improvements (medium, air-liquid interface chamber, imaging chamber with a double perfusion) aimed at optimizing the viability of microglial cells over several hours, especially in slices from adult mice.

Microglia, the resident immune cells of the brain, respond quickly with morphological changes to modifications of their environment. This protocol describes how to use two-photon microscopy to study the attraction of microglial processes toward serotonin or ATP in acute brain slices of mice.

Microglial cells are resident innate immune cells of the brain that constantly scan their environment with their long processes and, upon disruption of ...

Short-Term Free-Floating Slice Cultures from the Adult Human Brain

Organotypic, or slice cultures, have been widely employed to model aspects of the central nervous system functioning in vitro. Despite the potential of slice cultures in neuroscience, studies using adult nervous tissue to prepare such cultures are still scarce, particularly those from human subjects. The use of adult human tissue to prepare slice cultures is particularly attractive to enhance the understanding of human neuropathologies, as they hold unique properties typical of the mature human brain lacking in slices produced from rodent (usually neonatal) nervous tissue. This protocol describes how to use brain tissue collected from living human donors submitted to resective brain surgery to prepare short-term, free-floating slice cultures. Procedures to maintain and perform biochemical and cell biology assays using these cultures are also presented. Representative results demonstrate that the typical human cortical lamination is preserved in slices after 4 days in vitro (DIV4), with expected presence of the main neural cell types. Moreover, slices at DIV4 undergo robust cell death when challenged with a toxic stimulus (H2O2), indicating the potential of this model to serve as a platform in cell death assays. This method, a simpler and cost-effective alternative to the widely used protocol using membrane inserts, is mainly recommended for running short-term assays aimed to unravel mechanisms of neurodegeneration behind age-associated brain diseases. Finally, although the protocol is devoted to using cortical tissue collected from patients submitted to surgical treatment of pharmacoresistant temporal lobe epilepsy, it is argued that tissue collected from other brain regions/conditions should also be considered as sources to produce similar free-floating slice cultures.

A protocol to prepare free-floating slice cultures from adult human brain is presented. The protocol is a variation of the widely used slice culture method using membrane inserts. It is simple, cost-effective, and recommended for running short-term assays aimed to unravel mechanisms of neurodegeneration behind age-associated brain diseases.

Organotypic, or slice cultures, have been widely employed to model aspects of the central nervous system functioning in vitro. Despite the potential of ...

Minimizing Hypoxia in Hippocampal Slices from Adult and Aging Mice

Acute hippocampal slices have enabled generations of neuroscientists to explore synaptic, neuronal, and circuit properties in detail and with high fidelity. Exploration of LTP and LTD mechanisms, single neuron dendritic computation, and experience-dependent changes in circuitry, would not have been possible without this classical preparation. However, with a few exceptions, most basic research using acute hippocampal slices has been performed using slices from rodents of relatively young ages, ~P20-P40, even though synaptic and intrinsic excitability mechanisms have a long developmental tail that reaches past P60. The main appeal of using young hippocampal slices is preservation of neuronal health aided by higher tolerance to hypoxic damage. However, there is a need to understand neuronal function at more mature stages of development, further accentuated by the development of various animal models of neurodegenerative diseases that require an aging brain preparation. Here we describe a modification to an acute hippocampal slice preparation that reliably delivers healthy slices from adult and aging mouse hippocampi. The protocol&#8217;s critical steps are transcardial perfusion and cutting with ice-cold sodium-free NMDG-aSCF. Together, these steps attenuate the hypoxia-induced drop in ATP upon decapitation, as well as cytotoxic edema caused by passive sodium fluxes. We demonstrate how to cut transversal slices of hippocampus plus cortex using a vibrating microtome. Acute hippocampal slices obtained in this way are reliably healthy over many hours of recording, and are appropriate for both field-recordings and targeted patch-clamp recordings, including targeting of fluorescently labeled neurons.

This is a protocol for acute slice preparation from adult and aging mouse hippocampi that takes advantage of transcardial perfusion and slice cutting with ice-cold NMDG-aCSF to reduce hypoxic damage to the tissue. The resulting slices stay healthy over many hours, and are suitable for long-term patch-clamp and field-recordings.

Acute hippocampal slices have enabled generations of neuroscientists to explore synaptic, neuronal, and circuit properties in detail and with high ...

Preparing Acute Brain Slices from the Dorsal Pole of the Hippocampus from Adult Rodents

Whole-cell patch-clamp recordings from acute rodent brain slices are a mainstay of modern neurophysiological research, allowing precise measurement of cellular and synaptic properties. Nevertheless, there is an ever increasing need to perform correlated analyses between different experimental modes in addition to slice electrophysiology, for example: immunohistochemistry, molecular biology, in vivo imaging or electrophysiological recording; to answer evermore complex questions of brain function. However, making meaningful conclusions from these various experimental approaches is not straightforward, as even within relatively well described brain structures, a high degree of sub-regional variation of cellular function exists. Nowhere is this better exemplified than in the CA1 of the hippocampus, which has well-defined dorso-ventral properties, based on cellular and molecular properties. Nevertheless, many published studies examine protein expression patterns or behaviorally correlated in vivo activity in the dorsal extent of the hippocampus; and explain findings mechanistically with cellular electrophysiology from the ventro-medial region. This is further confounded by the fact that many acute slice electrophysiological experiments are performed in juvenile animals, when other experimental modes are performed in more mature animals. To address these issues, this method incorporates transcardial perfusion of mature (&#62;60 day old rodents) with artificial cerebrospinal fluid followed by preparation of modified coronal slices including the septal pole of the dorsal hippocampus to record from CA1 pyramidal cells. This process leads to the generation of healthy acute slices of dorsal hippocampus allowing for slice-based cellular electrophysiological interrogation matched to other measures.

The purpose of this protocol is to describe a method to produce slices of the dorsal hippocampus for electrophysiological examination. This procedure employs perfusion with chilled ACSF prior to slice preparation with a near-coronal slicing angle which allows for preservation of healthy principal neurons.

Whole-cell patch-clamp recordings from acute rodent brain slices are a mainstay of modern neurophysiological research, allowing precise measurement of ...

Acute Mouse Brain Slicing to Investigate Spontaneous Hippocampal Network Activity

Acute rodent brain slicing offers a tractable experimental approach to gain insight into the organization and function of neural circuits with single-cell resolution using electrophysiology, microscopy, and pharmacology. However, a major consideration in the design of in vitro experiments is the extent to which different slice preparations recapitulate naturalistic patterns of neural activity as observed in vivo. In the intact brain, the hippocampal network generates highly synchronized population activity reflective of the behavioral state of the animal, as exemplified by the sharp-wave ripple complexes (SWRs) that occur during waking consummatory states or non-REM sleep. SWRs and other forms of network activity can emerge spontaneously in isolated hippocampal slices under appropriate conditions. In order to apply the powerful brain slice toolkit to the investigation of hippocampal network activity, it is necessary to utilize an approach that optimizes tissue health and the preservation of functional connectivity within the hippocampal network. Mice are transcardially perfused with cold sucrose-based artificial cerebrospinal fluid. Horizontal slices containing the hippocampus are cut at a thickness of 450 &#956;m to preserve synaptic connectivity. Slices recover in an interface-style chamber and are transferred to a submerged chamber for recordings. The recording chamber is designed for dual surface superfusion of artificial cerebrospinal fluid at a high flow rate to improve oxygenation of the slice. This protocol yields healthy tissue suitable for the investigation of complex and spontaneous network activity in vitro.

This protocol describes the preparation of horizontal hippocampal-entorhinal cortex (HEC) slices from mice exhibiting spontaneous sharp-wave ripple activity. Slices are incubated in a simplified interface holding chamber and recordings are performed under submerged conditions with fast-flowing artificial cerebrospinal fluid to promote tissue oxygenation and the spontaneous emergence of network-level activity.

Acute rodent brain slicing offers a tractable experimental approach to gain insight into the organization and function of neural circuits with single-cell ...

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

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

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

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

Slice It Hot: Acute Adult Brain Slicing in Physiological Temperature

Samenvatting

Meer video's verkennen

Hoofdstukken in deze video