We thank Joung Jang and Xin Guan for technical assistance. We thank Dr. Rory McQuiston of Virginia Commonwealth University for setting up our first patch clamp rig and advices on experimental procedures. We thank Dr. Samuel Wu for suggestions on voltage clamp recording. The work is supported by NIH grants EY013811, EY022228 and a vision core grant EY002520. C-KC is the Alice R. McPherson Retina Research Foundation Endowed Chair at the Baylor College of Medicine.

Ethical approval &#8211; procedures involving animal subjects were conducted in accordance with the rules and regulations of the National Institutes of Health guidelines for research animals, as approved by the institutional animal care and use committee of Baylor College of Medicine.
1. External and Internal Solutions
<ol>
	<li>Use mammalian Ringer&#39;s solution during retina dissection and as the external solution in subsequent electrophysiological recording. Prepare the mammalian Ringer&#39;s solution from 10x stock solution (without calcium) on the day of recording, and add CaCl2 drop-wise after 15 min of carbogenation (95% O2 and 5% CO2). The final 1x solution contains (in mM): 120 NaCl, 5 KCl, 25 NaHCO3, 0.8 Na2HPO4, 0.1 NaH2PO4, 2 CaCl2, 1 MgSO4 and 10 D-glucose.</li>
	<li>Use two internal solutions to characterize SAC oscillations. Test the usefulness of prepared solutions in prolonged whole-cell patch clamp recordings on adult mouse RGCs and store the verified batches in 500 &#181;l aliquots at -20 &#176;C until use.
	<ol>
		<li>For recording membrane potential oscillation, use a potassium-based internal solution that contains (in mM): 125 K-gluconate, 8 NaCl, 4 ATP-Mg, 0.5 Li-GTP, 5 EGTA, 10 HEPES and 0.2% biocytin (w/v). Adjust pH to 7.3 with KOH.</li>
		<li>For recording excitatory and inhibitory postsynaptic currents, use a cesium-based internal solution that contains (in mM): 100 Cs-methanesulfonate, 8 NaCl, 4 ATP-Mg, 0.5 Li-GTP, 5 EGTA, 10 HEPES and 0.2% biocytin (w/v). Adjust pH to 7.3 with CsOH.</li>
	</ol>
	</li>
</ol>
2. Preparation for the Day of Recording
<ol>
	<li>To prepare a nitrocellulose membrane with open holes, manually punch the membrane with a customized puncher made from a blunted 16 G syringe needle and flatten the membrane between two clean glass plates. For a whole-mount retina, make a central hole 0.2 mm in diameter and surround it by 4 larger holes that are 1-1.2 mm in diameter.</li>
	<li>To make a customized backfill filament for loading internal solution into electrodes, melt a 10 &#181;l pipette tip in the middle and gently lengthen the melted portion until it cools and hardens. Just prior to use, use a clean razor blade to trim the filament until it is slightly longer than the patch pipettes.</li>
	<li>Pull patch pipettes in a programmable puller from borosilicate glass tube with an internal filament. Manufacture the micropipettes on the day of experiment and use them immediately. 
	NOTE: For recording SACs, we use the following puller setting: heat: 484; pull: 0; velocity: 25; delay time: 1; pressure: 400 and a ramp value of 462. The O.D. and I.D. of the borosilicate tubes are 1.65 mm and 1.0 mm, respectively. Resistance of the pipettes is 10-14 M&#937;.</li>
	<li>One hr before tissue harvest, thaw a tube of internal solution by shaking it on a vortex for &#62;30 min.</li>
</ol>
3. Retina Dissection
<ol>
	<li>Anesthetize the animal by 4% isoflurane in oxygen until the animal loses responsiveness to a toe pinch. Sacrifice the animal by cervical dislocation.</li>
	<li>Cut both eyeballs off the optic nerves at 1-2 mm away from the optic nerve heads with straight-pointed iris scissors.</li>
	<li>Roll the eyeballs on a clean paper towel to remove blood and then immerse them in carbogenated mammalian Ringer&#39;s solution. Punch a hole on the limbus with a 23 G needle and bisect the eyeballs by cutting along the limbus with micro-scissors. Remove the cornea and lens using fine forceps.
	<ol>
		<li>For retinal whole-mount, gently peel the entire retina off the pigmented epithelium with fine forceps and make four 1.5-2 mm orthogonal cuts from the edge toward the optic nerve head.</li>
	</ol>
	</li>
	<li>Immerse a punched nitrocellulose membrane into the dish and gently drag the retina over it with the GCL side up. Place the optic nerve head into the center hole when preparing a whole-mount retina. Transfer the membrane with the retina into another clean dish. Gently flatten the retina with a fine paint brush to look like a Maltese cross and lay all four edges over the holes.
	<ol>
		<li>If a fraction of the retina is to be examined at a time, cut each eyecup prepared from Step 3.3 into 3-4 pieces with a razor blade with the pigmented epithelium remains attached. Protect the unused pieces from light in carbogenated external solution and use them within 12 hr.</li>
	</ol>
	</li>
	<li>Blot the nitrocellulose membrane with a piece of dry filter paper and remove the vitreous and inner limiting membrane with forceps and a paint brush.</li>
	<li>Make sure that all retinal edges are fully attached to the membrane before transferring the assembly into the recording chamber with a sealed glass cover slip at the bottom. Secure the membrane with vacuum grease to the cover slip and rehydrate the retina with the external solution. Be careful not to trap any air bubbles underneath the assembly.</li>
	<li>Set the chamber onto the stage of an upright microscope. Perfuse the chamber with warm (34-35 &#176;C) carbogenated external solution at a rate of ~3 ml per min.</li>
	<li>Examine the retina under a 10x objective lens first, and then use a 60x water-immersion lens to see GCL and INL neurons under differential interference contrast (DIC) and/or epifluorescence. To visualize tdTomato-expressing SACs, use a white LED light source in combination with an excitation filter of 554 nm and an emission filter of 581 nm.</li>
</ol>
4. Whole-cell Patch Clamp Recording from Flat-mount Retina
<ol>
	<li>Filter the internal solution through a syringe filter into the custom backfill filament.</li>
	<li>Insert the filament into a freshly pulled micropipette and dispense the internal solution near the tip until the solution covers the silver electrode wire for &#62;5 mm. Fasten the micropipette onto an electrode holder with a suction pole, through which pressure inside the electrode can be adjusted by pushing or pulling the plunger of a tube-connected 10 ml plastic syringe.</li>
	<li>Find the pipette under the objective and bring it down to ~100 &#181;m above the retina. Under the current-follower mode (I = 0), use DC offset to zero the standing DC voltage signal. Measure the pipette resistance under the current clamp (IClamp) mode by injecting fixed amplitude square wave currents through the pipette while it is in the bath and neutralize the difference by turning the Raccess knob. Use the reading on the Raccess knob to calculate pipette resistance by the Ohm&#39;s law.</li>
	<li>Slowly bring the electrode to ~10 &#181;m above the retina. Apply positive pressure to the electrode. Watch the reflection change near the pipette tip as it approaches the retina. Quickly but gently force the pipette into the GCL and reduce the positive pressure immediately.</li>
	<li>Move the pipette toward a labeled neuron. Avoid contacting other neurons, blood vessels and endfeet of Muller cells. Apply more positive pressure if needed to prevent electrode clogging.</li>
	<li>Position the pipette tip near the midline of a labeled neuron until a dimple is visible. Release the positive pressure and allow the plasma membrane to bounce back onto the pipette tip.</li>
	<li>Apply 20 to 120 pA negative currents to the pipette to help the formation of a giga-ohm seal. Apply a gentle suction if necessary to pull the plasma membrane into the pipette. Wait 5 min after seal formation to rupture the cell membrane. This allows the spilled internal solution to be cleared by superfusion. Rupture the membrane by a gentle suction.</li>
	<li>After the membrane rupture and while in the current clamp mode, switch on bridge balance and adjust it using the Raccess knob. 
	NOTE: For a small cell like the SAC, only slight adjustment is needed, if any. Alternatively, record excitatory and inhibitory postsynaptic currents in the voltage clamp mode (VClamp) by holding the cell at reversal potentials of chloride (around -75 mV) and glutamate (around 0 mV), respectively. Check and adjust pipette position if needed to accommodate occasional retina and/or micromanipulator drift.</li>
	<li>To record membrane potential or current change before, during and after pharmacological treatment, prepare synaptic blockers (e.g., CNQX, AP5, picrotoxin, tubocurarine, etc.) and channel modulators (e.g., flupirtine, dopamine, meclofenamic acid, etc.) fresh on the day of experiment from frozen stocks. Dilute the drugs with carbogenated Ringer&#39;s solution. Apply them in a batch manner through perfusion.</li>
	<li>After recording, gently remove the pipette from the soma. Transfer the assembly from the chamber to a clean dish. Detach and re-attach the retina onto another flattened nitrocellulose membrane without punched holes to ensure retina flatness during fixation.</li>
	<li>Fix the retina by immersing it in 4% paraformaldehyde for 30 min at RT. Remove the retina from the nitrocellulose membrane and rinse it extensively with 1x PBS. Reveal the morphology of the recorded cells by O/N staining with dye-conjugated streptavidin diluted in 1x PBS with 0.4% Triton X-100 at 4 &#176;C14. Mount the retina in antifade medium and observe recorded cells using a scanning confocal microscope. 
	NOTE: Procedures involving paraformaldehyde, which is volatile and toxic, should be conducted in a draft chamber for safety.</li>
</ol>

<ol><li>Choi, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Intrinsic+bursting+of+AII+amacrine+cells+underlies+oscillations+in+the+rd1+mouse+retina%5BTitle%5D)+AND+%22J+Neurophysiol%22%5BJournal%5D)">Intrinsic bursting of AII amacrine cells underlies oscillations in the rd1 mouse retina.</a> J Neurophysiol. 112 (6), 1491-1504 (2014).</li>
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<li>Tu, H. Y., Chen, Y. J., Chiao, C. C., McQuiston, A. R., Chen, C. K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Rhythmic+membrane+potential+fluctuations+of+cholinergic+amacrine+cells+in+mice+lacking+ERG+b-waves%5BTitle%5D)+AND+%22Invest+Ophthalmol+Vis+Sci%22%5BJournal%5D)">Rhythmic membrane potential fluctuations of cholinergic amacrine cells in mice lacking ERG b-waves.</a> Invest Ophthalmol Vis Sci. 56 (7), (2015).</li>
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<li>Tu, H. Y., Chen, Y. J., McQuiston, A. R., Chiao, C. C., Chen, C. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+Novel+Retinal+Oscillation+Mechanism+in+an+Autosomal+Dominant+Photoreceptor+Degeneration+Mouse+Model%5BTitle%5D)+AND+%22Front+Cell+Neurosci%22%5BJournal%5D)">A Novel Retinal Oscillation Mechanism in an Autosomal Dominant Photoreceptor Degeneration Mouse Model.</a> Front Cell Neurosci. 9, 513(2015).</li>
<li>Borowska, J., Trenholm, S., Awatramani, G. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((An+intrinsic+neural+oscillator+in+the+degenerating+mouse+retina%5BTitle%5D)+AND+%22J+Neurosci%22%5BJournal%5D)">An intrinsic neural oscillator in the degenerating mouse retina.</a> J Neurosci. 31 (13), 5000-5012 (2011).</li>
<li>Margolis, D. J., Detwiler, P. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Cellular+origin+of+spontaneous+ganglion+cell+spike+activity+in+animal+models+of+retinitis+pigmentosa%5BTitle%5D)+AND+%22J+Ophthalmol%22%5BJournal%5D)">Cellular origin of spontaneous ganglion cell spike activity in animal models of retinitis pigmentosa.</a> J Ophthalmol. , (2011).</li>
<li>Stasheff, S. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Emergence+of+sustained+spontaneous+hyperactivity+and+temporary+preservation+of+OFF+responses+in+ganglion+cells+of+the+retinal+degeneration+%28rd1%29+mouse%5BTitle%5D)+AND+%22J+Neurophysiol%22%5BJournal%5D)">Emergence of sustained spontaneous hyperactivity and temporary preservation of OFF responses in ganglion cells of the retinal degeneration (rd1) mouse.</a> J Neurophysiol. 99 (3), 1408-1421 (2008).</li>
<li>Trenholm, S., Awatramani, G. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Origins+of+spontaneous+activity+in+the+degenerating+retina%5BTitle%5D)+AND+%22Front+Cell+Neurosci%22%5BJournal%5D)">Origins of spontaneous activity in the degenerating retina.</a> Front Cell Neurosci. 9, 277(2015).</li>
<li>Trenholm, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Intrinsic+oscillatory+activity+arising+within+the+electrically+coupled+AII+amacrine-ON+cone+bipolar+cell+network+is+driven+by+voltage-gated+Na%2B+channels%5BTitle%5D)+AND+%22J+Physiol%22%5BJournal%5D)">Intrinsic oscillatory activity arising within the electrically coupled AII amacrine-ON cone bipolar cell network is driven by voltage-gated Na+ channels.</a> J Physiol. 590 (Pt 10), 2501-2517 (2012).</li>
<li>Chen, C. K. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Cell-autonomous+changes+in+displaced+cholinergic+amacrine+cells+lacking+Gbeta5%5BTitle%5D)+AND+%22Invest+Ophthalmol+Vis+Sci%22%5BJournal%5D)">Cell-autonomous changes in displaced cholinergic amacrine cells lacking Gbeta5.</a> Invest Ophthalmol Vis Sci. 56 (7), (2015).</li>
<li>O'Brien, B. J., Isayama, T., Richardson, R., Berson, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Intrinsic+physiological+properties+of+cat+retinal+ganglion+cells%5BTitle%5D)+AND+%22J+Physiol%22%5BJournal%5D)">Intrinsic physiological properties of cat retinal ganglion cells.</a> J Physiol. 538 (Pt 3), 787-802 (2002).</li>
<li>Lee, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((An+Unconventional+Glutamatergic+Circuit+in+the+Retina+Formed+by+vGluT3+Amacrine+Cells%5BTitle%5D)+AND+%22Neuron%22%5BJournal%5D)">An Unconventional Glutamatergic Circuit in the Retina Formed by vGluT3 Amacrine Cells.</a> Neuron. 84 (4), 708-715 (2014).</li>
<li>Hoggarth, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Specific+wiring+of+distinct+amacrine+cells+in+the+directionally+selective+retinal+circuit+permits+independent+coding+of+direction+and+size%5BTitle%5D)+AND+%22Neuron%22%5BJournal%5D)">Specific wiring of distinct amacrine cells in the directionally selective retinal circuit permits independent coding of direction and size.</a> Neuron. 86 (1), 276-291 (2015).</li>
<li>Margolis, D. J., Gartland, A. J., Singer, J. H., Detwiler, P. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Network+oscillations+drive+correlated+spiking+of+ON+and+OFF+ganglion+cells+in+the+rd1+mouse+model+of+retinal+degeneration%5BTitle%5D)+AND+%22PLoS+One%22%5BJournal%5D)">Network oscillations drive correlated spiking of ON and OFF ganglion cells in the rd1 mouse model of retinal degeneration.</a> PLoS One. 9 (1), e86253(2014).</li>
<li>Schmidt, T. M., Kofuji, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((An+isolated+retinal+preparation+to+record+light+response+from+genetically+labeled+retinal+ganglion+cells%5BTitle%5D)+AND+%22J+Vis+Exp%22%5BJournal%5D)">An isolated retinal preparation to record light response from genetically labeled retinal ganglion cells.</a> J Vis Exp. (47), (2011).</li>
<li>Ivanova, E., Yee, C. W., Sagdullaev, B. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Increased+phosphorylation+of+Cx36+gap+junctions+in+the+AII+amacrine+cells+of+RD+retina%5BTitle%5D)+AND+%22Front+Cell+Neurosci%22%5BJournal%5D)">Increased phosphorylation of Cx36 gap junctions in the AII amacrine cells of RD retina.</a> Front Cell Neurosci. 9, 390(2015).</li>
<li>Enoki, R., Koizumi, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+method+of+horizontally+sliced+preparation+of+the+retina%5BTitle%5D)+AND+%22Methods+Mol+Biol%22%5BJournal%5D)">A method of horizontally sliced preparation of the retina.</a> Methods Mol Biol. 935, 201-205 (2013).</li>
<li>Akrouh, A., Kerschensteiner, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Morphology+and+function+of+three+VIP-expressing+amacrine+cell+types+in+the+mouse+retina%5BTitle%5D)+AND+%22J+Neurophysiol%22%5BJournal%5D)">Morphology and function of three VIP-expressing amacrine cell types in the mouse retina.</a> J Neurophysiol. 114 (4), 2431-2438 (2015).</li>
<li>Wei, W., Elstrott, J., Feller, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Two-photon+targeted+recording+of+GFP-expressing+neurons+for+light+responses+and+live-cell+imaging+in+the+mouse+retina%5BTitle%5D)+AND+%22Nat+Protoc%22%5BJournal%5D)">Two-photon targeted recording of GFP-expressing neurons for light responses and live-cell imaging in the mouse retina.</a> Nat Protoc. 5 (7), 1347-1352 (2010).</li>
</ol>

The authors have nothing to disclose.

Many labs have recorded from GCL neurons in the flat-mount preparation15-18, but our procedures allow recording from INL neurons. We hereby emphasize several steps that are critical for successful routine recordings.
The freshness and flatness of the retina are important for penetrating it with a recording pipette. In this regard, the firm attachment of the retina to the punched nitrocellulose membrane is paramount and is achieved by transient absorption of solution followed by time...

As an easily accessible part of the central nervous system, the retina has for decades been a useful model in neuroscience studies. Genetic marking of neurons has allowed detailed characterization of synaptic connections in the retina. With many methodologies available to examine function and morphology of retinal neurons, the patch clamp recording technique has been instrumental in our current understanding of vertically transmitted signals in the retina. These signals are originated from photon absorption in photoreceptors and sent to brain visual centers through spiking of retinal ganglion cells (RGCs). Despite a large body of knowledge accumulated thus far, neural diversity in vascularized mammalian retina remains unsolved and obstructs the full appreciation of retinal circuits that subserve normal vision. This is in part because most recordings were performed on retinal slices to trade lateral circuit integrity for access to more proximal retinal neurons1-3. To gain a comprehensive picture on how retina computes visual signals, it is thus desirable to record neurons in flat-mounts wherein lateral connections, large and small, may be better preserved.
When synaptic transmission from photoreceptors to bipolar cells is interrupted due to a defective metabotropic glutamate receptor 6 (mGluR6) signaling pathway in depolarizing bipolar cells4-6 or simply as the result of photoreceptor loss in degenerated retinas7-10, many RGCs exhibit oscillatory activities. These oscillations originate from multiple sources, however the one involving gap junction coupling between AII amacrine cells (AII-ACs) and depolarizing cone bipolar cells (DCBCs) has received the most attention and hence is best understood1,7,11. We have found another source, which persists under pharmacological blockade of the aforementioned AII-AC/DCBC network and drives oscillation of OFF-type SACs in Rho&#916;CTA and Nob mice with deafferentated retinas7,8,12. Here we detail our protocol of preparing retinal flat-mounts for INL neuron recording. This approach uses commercial mouse lines (Jax stock no. 006410 and 007905) to mark cholinergic retinal neurons by fluorescent protein (tdTomato) expression that is identifiable under a fluorescent microscope equipped with contrast enhancing optics. Some experimental results acquired through this approach have been previously reported4,5,7,13.

<table><tbody><tr><td>Fixed-stage fluorescent microscope with DIC</td><td>Olympus</td><td>BX51-WI</td><td></td></tr><tr><td>Micromanipulators</td><td>Sutter</td><td>MP-225</td><td></td></tr><tr><td>Patch clamp amplifier</td><td>A-M System</td><td>AM2400</td><td></td></tr><tr><td>AD converter</td><td>National Instrument</td><td>NI-USB-6221</td><td></td></tr><tr><td>Heater controller</td><td>Warner Instrument</td><td>TC-324B</td><td></td></tr><tr><td>Inline heater</td><td>Warner Instrument</td><td>SC-20</td><td></td></tr><tr><td>Peristaltic pump</td><td>Rainin</td><td>Dynamax</td><td></td></tr><tr><td>pipette puller</td><td>Sutter Instrument</td><td>P-1000</td><td></td></tr><tr><td>Glass tube with filament</td><td>King Precision Glass</td><td>Customized</td><td></td></tr><tr><td>Stimulator</td><td>A.M.P.I.</td><td>Master-8</td><td></td></tr><tr><td>Biocytin</td><td>Sigma</td><td>B4261</td><td></td></tr><tr><td>NaCl</td><td>Sigma</td><td>S6191</td><td></td></tr><tr><td>KCl</td><td>Sigma</td><td>P5405</td><td></td></tr><tr><td>NaHCO&lt;sub&gt;3&lt;/sub&gt;</td><td>Fisher</td><td>BP328-1</td><td></td></tr><tr><td>Na&lt;sub&gt;2&lt;/sub&gt;HPO&lt;sub&gt;4&lt;/sub&gt;</td><td>Sigma</td><td>S0876</td><td></td></tr><tr><td>Na&lt;sub&gt;2&lt;/sub&gt;HPO&lt;sub&gt;4&lt;/sub&gt;</td><td>Sigma</td><td>S5011</td><td></td></tr><tr><td>CaCl&lt;sub&gt;2&lt;/sub&gt;</td><td>Sigma</td><td>C5670</td><td></td></tr><tr><td>MgSO&lt;sub&gt;4&lt;/sub&gt;</td><td>Sigma</td><td>M1880</td><td></td></tr><tr><td>D-glucose</td><td>Sigma</td><td>G6152</td><td></td></tr><tr><td>K-gluconate</td><td>Sigma</td><td>G4500</td><td></td></tr><tr><td>ATP-Mg</td><td>Sigma</td><td>A9187</td><td></td></tr><tr><td>Li-GTP</td><td>Sigma</td><td>G5884</td><td></td></tr><tr><td>EGTA</td><td>Sigma</td><td>E0396</td><td></td></tr><tr><td>HEPES</td><td>Sigma</td><td>H4034</td><td></td></tr><tr><td>KOH</td><td>Sigma</td><td>P5958</td><td></td></tr><tr><td>Cs-methanesulfonate</td><td>Sigma</td><td>C1426</td><td></td></tr><tr><td>CsOH</td><td>Sigma</td><td>232041</td><td></td></tr><tr><td>Syringer filter</td><td>Nalgene</td><td>171</td><td></td></tr><tr><td>1 ml syring</td><td>Rainin</td><td>17013002</td><td></td></tr><tr><td>10 &amp;mu;l pipette tip</td><td>Genesee Scientific</td><td>24-130RL</td><td></td></tr><tr><td>Streptavidin-488</td><td>ThermoFisher</td><td>S-11223</td><td></td></tr><tr><td>10x PBS</td><td>Lonza</td><td>17-517Q</td><td></td></tr></tbody></table>

patch clamp recording of starburst amacrine cells in a flat-mount preparation of deafferentated mouse retina

The mammalian retina is a layered tissue composed of multiple neuronal types. To understand how visual signals are processed within its intricate synaptic network, electrophysiological recordings are frequently used to study connections among individual neurons. We have optimized a flat-mount preparation for patch clamp recording of genetically marked neurons in both GCL (ganglion cell layer) and INL (inner nuclear layer) of mouse retinas. Recording INL neurons in flat-mounts is favored over slices because both vertical and lateral connections are preserved in the former configuration, allowing retinal circuits with large lateral components to be studied. We have used this procedure to compare responses of mirror-partnered neurons in retinas such as the cholinergic starburst amacrine cells (SACs).

Representative recordings of ON- and OFF-type SACs from a deafferentated mouse retina are shown in Figure 1. Cholinergic cells in both GCL and INL can be reliably identified by tdTomato fluorescence and targeted for whole-cell patch clamp recording under DIC (Figure 1A) to reveal oscillation of their membrane potentials (top traces) and the synaptic currents that drive it (bottom traces, Figure 1B). Inhibitory and excitatory synaptic curr...

Watch this Scientific Journal Video about Patch Clamp Recording of Starburst Amacrine Cells in a Flat-mount Preparation of Deafferentated Mouse Retina at JoVE.com

Patch Clamp Recording of Starburst Amacrine Cells in a Flat-mount Preparation of Deafferentated Mouse Retina

This protocol demonstrates how to perform whole-cell patch clamp recording on retinal neurons from a flat-mount preparation.

The mammalian retina is a layered tissue composed of multiple neuronal types. To understand how visual signals are processed within its intricate synaptic ...

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8.2K Views.  Baylor College of Medicine.  Dit protocol laat zien hoe whole-cell patch clamp opname uit te voeren op het netvlies neuronen uit een flat-mount voorbereiding. 

Video: Patch Clamp Recording of Starburst Amacrine Cells in a Flat-mount Preparation of Deafferentated Mouse Retina

Patch Clamp Recordings from Mouse Retinal Neurons in a Dark-adapted Slice Preparation

Our visual experience is initiated when the visual pigment in our retinal photoreceptors absorbs photons of light energy and initiates a cascade of intracellular events that lead to closure of cyclic-nucleotide-gated channels in the cell membrane. The resulting change in membrane potential leads in turn to reductions in the amount of neurotransmitter release from both rod and cone synaptic terminals. To measure how the light-evoked change in photoreceptor membrane potential leads to downstream activity in the retina, scientists have made electrophysiological recordings from retinal slice preparations for decades1,2. In the past these slices have been cut manually with a razor blade on retinal tissue that is attached to filter paper; in recent years another method of slicing has been developed whereby retinal tissue is embedded in low gelling temperature agar and sliced in cool solution with a vibrating microtome3,4. This preparation produces retinal slices with less surface damage and very robust light-evoked responses. Here we document how this procedure can be done under infrared light to avoid bleaching the visual pigment.

Here we describe a procedure for generating dark-adapted slices of the mouse retina for electrophysiological recordings.

Our visual experience is initiated when the visual pigment in our retinal photoreceptors absorbs photons of light energy and initiates a cascade of ...

An Isolated Retinal Preparation to Record Light Response from Genetically Labeled Retinal Ganglion Cells

The first steps in vertebrate vision take place when light stimulates the rod and cone photoreceptors of the retina 1. This information is then segregated into what are known as the ON and OFF pathways. The photoreceptors signal light information to the bipolar cells (BCs), which depolarize in response to increases (On BCs) or decreases (Off BCs) in light intensity. This segregation of light information is maintained at the level of the retinal ganglion cells (RGCs), which have dendrites stratifying in either the Off sublamina of the inner plexiform layer (IPL), where they receive direct excitatory input from Off BCs, or stratifying in the On sublamina of the IPL, where they receive direct excitatory input from On BCs. This segregation of information regarding increases or decreases in illumination (the On and Off pathways) is conserved and signaled to the brain in parallel.
The RGCs are the output cells of the retina, and are thus an important cell to study in order to understand how light information is signaled to visual nuclei in the brain. Advances in mouse genetics over recent decades have resulted in a variety of fluorescent reporter mouse lines where specific RGC populations are labeled with a fluorescent protein to allow for identification of RGC subtypes 2 3 4 and specific targeting for electrophysiological recording. Here, we present a method for recording light responses from fluorescently labeled ganglion cells in an intact, isolated retinal preparation. This isolated retinal preparation allows for recordings from RGCs where the dendritic arbor is intact and the inputs across the entire RGC dendritic arbor are preserved. This method is applicable across a variety of ganglion cell subtypes and is amenable to a wide variety of single-cell physiological techniques.

This article provides a description of how to dissect and record from the isolated retinal preparation in mouse. In particular, we describe how to record light responses from a fluorescently labeled ganglion cell population and subsequently identify and analyze its morphology.

The first steps in vertebrate vision take place when light stimulates the rod and cone photoreceptors of the retina 1.  This information is then ...

Transretinal ERG Recordings from Mouse Retina: Rod and Cone Photoresponses

There are two distinct classes of image-forming photoreceptors in the vertebrate retina: rods and cones. Rods are able to detect single photons of light whereas cones operate continuously under rapidly changing bright light conditions. Absorption of light by rod- and cone-specific visual pigments in the outer segments of photoreceptors triggers a phototransduction cascade that eventually leads to closure of cyclic nucleotide-gated channels on the plasma membrane and cell hyperpolarization. This light-induced change in membrane current and potential can be registered as a photoresponse, by either classical suction electrode recording technique1,2 or by transretinal electroretinogram recordings (ERG) from isolated retinas with pharmacologically blocked postsynaptic response components3-5. The latter method allows drug-accessible long-lasting recordings from mouse photoreceptors and is particularly useful for obtaining stable photoresponses from the scarce and fragile mouse cones. In the case of cones, such experiments can be performed both in dark-adapted conditions and following intense illumination that bleaches essentially all visual pigment, to monitor the process of cone photosensitivity recovery during dark adaptation6,7. In this video, we will show how to perform rod- and M/L-cone-driven transretinal recordings from dark-adapted mouse retina. Rod recordings will be carried out using retina of wild type (C57Bl/6) mice. For simplicity, cone recordings will be obtained from genetically modified rod transducin &alpha;-subunit knockout (T&alpha;-/-) mice which lack rod signaling8.

We describe a relatively simple method of transretinal electroretinogram (ERG) recordings for obtaining rod and cone photoresponses from intact mouse retina. This approach takes advantage of the block of synaptic transmission from photoreceptors to isolate their light responses and record them using field electrodes placed across the isolated flat-mounted retina.

There are two distinct classes of image-forming photoreceptors in the vertebrate retina: rods and cones. Rods are able to detect single photons of light ...

Electrophysiological Characterization of GFP-Expressing Cell Populations in the Intact Retina

Studying the physiological properties and synaptic connections of specific neurons in the intact tissue is a challenge for those cells that lack conspicuous morphological features or show a low population density. This applies particularly to retinal amacrine cells, an exceptionally multiform class of interneurons that comprise roughly 30 subtypes in mammals1. Though being a crucial part of the visual processing by shaping the retinal output2, most of these subtypes have not been studied up to now in a functional context because encountering these cells with a recording electrode is a rare event.
Recently, a multitude of transgenic mouse lines is available that express fluorescent markers like green fluorescent protein (GFP) under the control of promoters for membrane receptors or enzymes that are specific to only a subset of neurons in a given tissue3,4. These pre-labeled cells are therefore accessible to directed microelectrode targeting under microscopic control, permitting the systematic study of their physiological properties in situ. However, excitation of fluorescent markers is accompanied by the risk of phototoxicity for the living tissue. In the retina, this approach is additionally hampered by the problem that excitation light causes appropriate stimulation of the photoreceptors, thus inflicting photopigment bleaching and transferring the retinal circuits into a light-adapted condition. These drawbacks are overcome by using infrared excitation delivered by a mode-locked laser in short pulses of the femtosecond range. Two-photon excitation provides energy sufficient for fluorophore excitation and at the same time restricts the excitation to a small tissue volume minimizing the hazards of photodamage5. Also, it leaves the retina responsive to visual stimuli since infrared light (&gt;850 nm) is only poorly absorbed by photopigments6.
In this article we demonstrate the use of a transgenic mouse retina to attain electrophysiological in situ recordings from GFP-expressing cells that are visually targeted by two-photon excitation. The retina is prepared and maintained in darkness and can be subjected to optical stimuli which are projected through the condenser of the microscope (Figure 1). Patch-clamp recording of light responses can be combined with dye filling to reveal the morphology and to check for gap junction-mediated dye coupling to neighboring cells, so that the target cell can by studied on different experimental levels.

This article depicts the recording of individual cells from fluorescently tagged neuronal populations in the intact mouse retina. By using two-photon infrared excitation transgenetically labeled cells were targeted for patch-clamp recording to study their light responses, receptive field properties, and morphology.

Studying the physiological properties and synaptic connections of specific neurons in the intact tissue is a challenge for those cells that lack ...

Implementing Dynamic Clamp with Synaptic and Artificial Conductances in Mouse Retinal Ganglion Cells

Ganglion cells are the output neurons of the retina and their activity reflects the integration of multiple synaptic inputs arising from specific neural circuits. Patch clamp techniques, in voltage clamp and current clamp configurations, are commonly used to study the physiological properties of neurons and to characterize their synaptic inputs. Although the application of these techniques is highly informative, they pose various limitations. For example, it is difficult to quantify how the precise interactions of excitatory and inhibitory inputs determine response output. To address this issue, we used a modified current clamp technique, dynamic clamp, also called conductance clamp 1, 2, 3 and examined the impact of excitatory and inhibitory synaptic inputs on neuronal excitability. This technique requires the injection of current into the cell and is dependent on the real-time feedback of its membrane potential at that time. The injected current is calculated from predetermined excitatory and inhibitory synaptic conductances, their reversal potentials and the cell's instantaneous membrane potential. Details on the experimental procedures, patch clamping cells to achieve a whole-cell configuration and employment of the dynamic clamp technique are illustrated in this video article. Here, we show the responses of mouse retinal ganglion cells to various conductance waveforms obtained from physiological experiments in control conditions or in the presence of drugs. Furthermore, we show the use of artificial excitatory and inhibitory conductances generated using alpha functions to investigate the responses of the cells.

This video article illustrates the set-up, the procedures to patch cell bodies and how to implement dynamic clamp recordings from ganglion cells in whole-mount mouse retinae. This technique allows the investigation of the precise contribution of excitatory and inhibitory synaptic inputs, and their relative magnitude and timing to neuronal spiking.

Ganglion cells are the output neurons of the  retina and their activity reflects the integration of multiple synaptic inputs  arising from specific neural ...

Recording Light-evoked Postsynaptic Responses in Neurons in Dark-adapted, Mouse Retinal Slice Preparations Using Patch Clamp Techniques

The retina is the gateway to the visual system. To understand visual signal processing mechanisms, we investigate retinal neural network functions. Retinal neurons in the network comprise of numerous subtypes. More than 10 subtypes of bipolar cells, ganglion cells, and amacrine cells have been identified by morphological studies. Multiple subtypes of retinal neurons are thought to encode distinct features of visual signaling, such as motion and color, and form multiple neural pathways. However, the functional roles of each neuron in visual signal processing are not fully understood. The patch clamp method is useful to address this fundamental question. Here, a protocol to record light-evoked synaptic responses in mouse retinal neurons using patch clamp recordings in dark-adapted conditions is provided. The mouse eyes are dark-adapted O/N, and retinal slice preparations are dissected in a dark room using infrared illumination and viewers. Infrared light does not activate mouse photoreceptors and thus preserves their light responsiveness. Patch clamp is used to record light-evoked responses in retinal neurons. A fluorescent dye is injected during recordings to characterize neuronal morphological subtypes. This procedure enables us to determine the physiological functions of each neuron in the mouse retina.

We will demonstrate how to prepare retinal slices from the mouse eye and record light responses in retinal neurons. The entire procedure is conducted in dark-adapted conditions.

The retina is the gateway to the visual system. To understand visual signal processing mechanisms, we investigate retinal neural network functions. ...

Preparation of Horizontal Slices of Adult Mouse Retina for Electrophysiological Studies

Vertical slice preparations are well established to study circuitry and signal transmission in the adult mammalian retina. The plane of sectioning in these preparations is perpendicular to the retinal surface, making it ideal for the study of radially oriented neurons like photoreceptors and bipolar cells. However, the large dendritic arbors of horizontal cells, wide-field amacrine cells, and ganglion cells are mostly truncated, leaving markedly reduced synaptic activity in these cells. Whereas ganglion cells and displaced amacrine cells can be studied in a whole-mounted preparation of the retina, horizontal cells and amacrine cells located in the inner nuclear layer are only poorly accessible for electrodes in whole retina tissue.
To achieve maximum accessibility and synaptic integrity, we developed a horizontal slice preparation of the mouse retina, and studied signal transmission at the synapse between photoreceptors and horizontal cells. Horizontal sectioning allows&#160;(1) easy and unambiguous visual identification of horizontal cell bodies for electrode targeting, and (2) preservation of the extended horizontal cell dendritic fields, as a prerequisite for intact and functional cone synaptic input to horizontal cell dendrites.
Horizontal cells from horizontal slices exhibited tonic synaptic activity in the dark, and they responded to brief flashes of light with a reduction of inward current and diminished synaptic activity. Immunocytochemical evidence indicates that almost all cones within the dendritic field of a horizontal cell establish synapses with its peripheral dendrites. The horizontal slice preparation is therefore well suited to study the physiological properties of horizontally extended retinal neurons as well as sensory signal transmission and integration across selected synapses.

We developed a horizontal slice preparation of the adult mammalian retina with the plane of sectioning parallel to the retinal surface. Dendritic fields of nonradially oriented retinal neurons were not truncated, allowing the study of signal processing with patch-clamp and imaging techniques.

Vertical slice preparations are well established to study circuitry and signal transmission in the adult mammalian retina. The plane of sectioning in ...

Studying Bipolar and Horizontal Neuronal Cells in the Murine Split Retina

Split Retina as an Improved Flatmount Preparation for Studying Inner Nuclear Layer Neurons in Vertebrate Retina

Bipolar cells and horizontal cells of the vertebrate retina are the first neurons to process visual information after photons are detected by photoreceptors. They perform fundamental operations such as light adaptation, contrast sensitivity, and spatial and color opponency. A complete understanding of the precise circuitry and biochemical mechanisms that govern their behavior will advance visual neuroscience research and ophthalmological medicine. However, current preparations for examining bipolar and horizontal cells (retinal whole mounts and vertical slices) are limited in their capacity to capture the anatomy and physiology of these cells. In this work, we present a method for removing photoreceptor cell bodies from live, flatmount mouse retinas, providing enhanced access to bipolar and horizontal cells for efficient patch clamping and rapid immunolabeling. Split retinas are prepared by sandwiching an isolated mouse retina between two pieces of nitrocellulose, then gently peeling them apart. The separation splits the retina just above the outer plexiform layer to yield two pieces of nitrocellulose, one containing the photoreceptor cell bodies and another containing the remaining inner retina. Unlike vertical retina slices, the split retina preparation does not sever the dendritic processes of inner retinal neurons, allowing for recordings from bipolar and horizontal cells that integrate the contributions of gap junction-coupled networks and wide-field amacrine cells. This work demonstrates the versatility of this preparation for the study of horizontal and bipolar cells in electrophysiology, immunohistochemistry, and in situ hybridization experiments.

Author Spotlight: Using the Split Retina Technique for Enhanced Access and Accelerated Experiments 

This work presents an alternative flatmount retina preparation in which the removal of photoreceptor cell bodies enables faster antibody diffusion and improved patch pipette access to inner retinal neurons for immunohistochemistry, in situ hybridization, and electrophysiology experiments.

Bipolar cells and horizontal cells of the vertebrate retina are the first neurons to process visual information after photons are detected by ...

Light-Evoked Postsynaptic Responses in Neurons of Mouse Retinal Slices

Source: Hellmer, C. B., et al. <a href="https://app.jove.com/v/52422">Recording Light-evoked Postsynaptic Responses in Neurons in Dark-adapted, Mouse Retinal Slice Preparations Using Patch Clamp Techniques.</a> J. Vis. Exp. (2015).
This video demonstrates the recording of light-evoked post-synaptic responses in a dark-adapted mouse retinal tissue slice preparation. The retinal slice is placed in a recording chamber, and a recording pipette is used to establish electrical continuity with a retinal ganglion cell. Light pulses are applied to generate excitatory post-synaptic potentials in the ganglion cells, which are recorded by the pipette.

All procedures involving sample collection have been performed in accordance with the institute&#39;s IRB guidelines.
1. Preparation of Experimental ...

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Imaging and Optical Techniques

Establishing a Whole-Cell Patch Clamp for Electrophysiological Recording from a Flat-Mount Mouse Retina

Source: Tu, H., et al. <a href="https://app.jove.com/v/54608">Patch Clamp Recording of Starburst Amacrine Cells in a Flat-mount Preparation of Deafferentated Mouse Retina.</a> J. Vis. Exp. (2016).
This video demonstrates a whole-cell patch-clamp technique for electrophysiological recording from a flat-mount mouse retina. A thin glass pipette with an electrode is used to approach starburst amacrine cells (SACs) within the retina. After forming a seal, suction is applied to rupture the membrane and form the whole-cell patch-clamp configuration. Finally, the flow of ions through the SAC synaptic receptors is measured using the configuration.

All procedures involving sample collection have been performed in accordance with the institute&#39;s IRB guidelines.
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Patch Clamp Recording of Starburst Amacrine Cells in a Flat-mount Preparation of Deafferentated Mouse Retina

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