Funded by the NIH (NS-18205).

1. Preparation of Fish for Paired Recordings
<ol>
	<li>Prior to beginning the procedure, prepare five key solutions, which include: Bath Solution, Bath Solution with Tricaine (MS222), Bath Solution with Formamide, Neuron Internal Solution and Muscle Internal Solution.</li>
	<li>Next, collect a single larval zebrafish between the ages of 72 to 96 hours and place in Bath Solution with Tricaine. Within one minute of exposure to the anesthetic, the fish will not respond to touch.</li>
	<li>Place the fish on top of a plastic dish and, using a stereomicroscope, decapitate with a double edge razor blade. </li>
	<li>Transfer the fish to a glass recording chamber coated with sylgard and filled with Bath Solution. Fasten at each end by inserting electrolytically sharpened tungsten pins through the notochord. </li>
	<li>Create a skin flap near the rostral end of the fish with a pin that will provide a adequate grip for a pair of fine forceps. Remove the overlying skin by gripping it near the rostral pin with a pair of fine forceps. Peel slowly in the caudal direction to remove the skin. </li>
	<li>Treat the fish with 3 mls of Bath Solution with Formamide for 3-5 minutes to block muscle contractions that might interfere with recordings. Wash 5 times with normal Bath Solution. Remove part of the superficial layer of muscle over 5 to 6 segments by gently scrapping with the side of a tungsten pin. </li>
	<li>Transfer the fish to an upright microscope located in a Faraday cage to shield electrical noise. The microscope is equipped with a fixed stage, long working distance 40x objective and zoom of .5 to 4x. The microscope is mounted on a motorized X-Y translation stage in order to move the preparation between nerve and muscle under high power. The use of differential interference contrast optics helps to visualize the neurons. </li>
	<li>Under 0.5 x zoom, use a wide bore 15-micron pipette to remove overlying muscle and expose the spinal cord. Negative pressure is applied through a 3 cc disposable syringe and muscle cells are removed one by one. This procedure is repeated for 5 to 6 dorsal segments of skeletal muscle. The same wide bore pipette is used to also remove the upper two layers of ventral muscle to obtain target fast skeletal muscle.</li>
	<li>This completes the preparation for paired recordings and the microscope zoom is increased to approximately 1.6x.</li>
</ol>
2. Paired Recordings of CaP Motor-neuron and Target Muscle Cells
<ol>
	<li>The cleaned segments are scanned to locate the CaP neurons. Each hemi-segment of spinal cord contains one large, 10 micron diameter, CaP motor-neuron. This teardrop shaped soma is located superficially under the spinal dura near the caudal most end of the segmental boundary. A CaP neuron is chosen for recording and the ventral target muscle in the adjacent caudal segment is scanned to check integrity. </li>
	<li>Two patch electrodes are positioned for recording, one for the neuron and a second for muscle. The upper electrode has a shallow taper for penetration of the tough spinal dura and tip opening of approximately 2 microns. The lower electrode has a steeper taper for low resistance voltage clamp recording of skeletal muscle </li>
	<li>Position the neuron electrode at an angle of approximately 30 degrees to penetrate the spinal dura, about one half-segment rostral to the selected CaP neuron. Advance the electrode using an axial drive manipulator while applying a gentle continuous positive pressure of approximately 60 millimeters mercury. As the electrode breaks through the dura, the CaP neuron may be displaced by the perfusion from the electrode, requiring a readjustment of the focus.</li>
	<li>When the electrode touches the CaP neuron soma positive pressure is released and usually results in immediate formation of a gigaohm seal. However, in some cases where a seal fails to form, it becomes necessary to apply a gentle negative pressure. After seal formation, the electrode potential is adjusted to -80mV and application of negative pressure ruptures the cell membrane. The CaP neuron is characterized by an input resistance of 140 to 180 Mega-ohms and an action potential that overshoots +40 millivolts. This is tested by injecting incrementally increasing depolarizing steps under current clamp until the action potential is elicited.</li>
	<li>Next, the microscope is relocated to ventral muscle using the X-Y motorized translator under high power. A fast muscle cell is chosen from the target field.</li>
	<li>The muscle electrode is advanced toward the target muscle cell under positive pressure, which when released, forms a gigaohm seal. The electrode potential is adjusted to -50 millivolts to inactivate sodium channels and under gentle suck the cell membrane is ruptured. A drop in resistance to 100 to 200 Mega-ohms and the sudden appearance of the large capacitive transients signals entry. 	</li>
	<li>To test for paired recording, the motor-neuron is depolarized by incrementally larger injections of current until an action potential is elicited. At this point an endplate current should be elicited in muscle. Continued stimulation of the motorneuron at 1 Hertz results in endplate currents without failure. As the stimulus frequency is increased to 100 Hertz the endplate currents fluctuate in amplitude and undergo functional depletion within 10 seconds of stimulation.</li>
</ol>
3. Representative Results
Typically, the neuron recording is stable for up to one hour but the muscle cells deteriorate as reflected as an increase in the series resistance. When this occurs the experiment is either terminated or another muscle cell is patch clamped. All recordings should be completed within one hour.
<img src="/files/ftp_upload/2351/2351fig1.jpg" alt="Figure 1" /> Figure 1. Recordings of the motorneuron action potential (AP, top) and the associated muscle endplate current (EPC, bottom). The action potential for a CaP neuron should overshoot +40 mV and the EPC should rise within 300 &mu;sec and decay along an exponential time course with a time constant under 1 msec.
<table border="1">
 <tbody>
 <tr>
 <td>Name </td>
 <td>Recipe</td>
 </tr>
 <tr>
 <td>Bath Solution (in mM)</td>
 <td>134 NaCl, 2.9 KCl, 2.1 CaCl2, 1.2 MgCl2, 10 Glucose, 10 Na-HEPES, pH 7.8</td>
 </tr>
 <tr>
 <td>Bath Solution with Tricaine</td>
 <td>Bath Solution containing 0.02% tricaine</td>
 </tr>
 <tr>
 <td>Bath Solution with Formamide</td>
 <td>Bath Solution containing 2M formamide</td>
 </tr>
 <tr>
 <td>Neuron Internal Solution (in mM)</td>
 <td>115 K-gluconate, 15 KCl, 2 MgCl2, 10 K-HEPES, 5 K-EGTA, 4 Mg-ATP, pH 7.2</td>
 </tr>
 <tr>
 <td>Muscle Internal Solution (in mM)</td>
 <td>120 KCl, 10 K-HEPES, 5 BAPTA, pH 7.4</td>
 </tr>
 </tbody>
</table>
Table 1. Solutions.

<ol>
	<li>Fetcho, J. R., O'Malley, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+neuronal+networks+in+behaving+animals.">Imaging neuronal networks in behaving animals.</a> Current Opinion in Neurobiology. 7, 832-838 (1997).</li><li>Fetcho, J. R., S, H. i. g. a. s. h. i. j. i. m. a. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+and+genetic+approaches+toward+understanding+neuronal+circuits+in+zebrafish.">Optical and genetic approaches toward understanding neuronal circuits in zebrafish.</a> Integr Comp Biol. 44, 57-70 (2004).</li><li>Iba&#241;ez-Tallon, I., Wen, H., Miwa, J., Xing, J., Aslantas-Tekinay, A., Ono, F., Brehm, P., Heintz, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tethering+naturally+occurring+peptide+toxins+for+cell+autonomous+modulation+of+ion+channels+and+receptors+in+vivo.">Tethering naturally occurring peptide toxins for cell autonomous modulation of ion channels and receptors in vivo.</a> Neuron. 43, 305-311 (2004).</li><li>Li, W., Ono, F., Brehm, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+measurements+of+presynaptic+release+in+mutant+zebrafish+lacking+postsynaptic+receptors.">Optical measurements of presynaptic release in mutant zebrafish lacking postsynaptic receptors.</a> J. Neuroscience. , 23-10467 (2003).</li><li>Ono, F., Mandel, G., Brehm, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acetylcholine+receptors+direct+rapsyn+clusters+to+the+neuromuscular+synapse+in+zebrafish.">Acetylcholine receptors direct rapsyn clusters to the neuromuscular synapse in zebrafish.</a> J. Neuroscience. 24, 475-5481 (2004).</li><li>Ono, F., Shcherbatko, A., Higashijima, S., Fetcho, J., Mandel, G., Brehm, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Paralytic+zebrafish+lacking+ACh+receptors+fail+to+localize+rapsyn+clusters+to+the+synapse.">Paralytic zebrafish lacking ACh receptors fail to localize rapsyn clusters to the synapse.</a> J. Neuroscience. 21, 5439-5448 (2001).</li><li>Ono, F., Shcherbatko, A., Higashijima, S., Mandel, G., Brehm, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+zebrafish+motility+mutant+twitch+once+reveals+new+roles+for+rapsyn+in+synaptic+function.">The zebrafish motility mutant twitch once reveals new roles for rapsyn in synaptic function.</a> J. Neuroscience. 22, 6491-6498 (2002).</li><li>Wang, M., Wen, H., Brehm, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Function+of+neuromuscular+synapses+in+the+zebrafish+choline-acetyltransferase+mutant+bajan.">Function of neuromuscular synapses in the zebrafish choline-acetyltransferase mutant bajan.</a> J Neurophysiol. , 100-104 (2008).</li><li>Wen, H., Brehm, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Paired+motor-neuron+muscle+recordings+in+zebrafish+test+the+receptor+blockade+model+for+shaping+synaptic+current.">Paired motor-neuron muscle recordings in zebrafish test the receptor blockade model for shaping synaptic current.</a> J. Neuroscience. 25, 8104-8111 (2005).</li></ol>

No conflicts of interest declared.

We have been using zebrafish paired recordings (Wen and Brehm, 2005) principally to study the processes of vesicle release and recycling during high frequency stimulation. This process is disrupted in motility mutants wherein normal synaptic transmission is compromised due to point mutations in key synaptic components. For example, mutations that disrupt postsynaptic receptor aggregates (Ono et al., 2001, 2002, 2004) and synthesis of presynaptic transmitter (Wang et al., 2008) result in un-coordinated swimming. Paired recordings provide the information that can pinpoint the source of the functional defect, thus linking behavior, genetics and physiology. It should now be possible to further dissect the processes underlying synaptic transmission by means of transient expression in the CaP motor-neurons using judicious promoters. In this way dominant negative or mutated genes can be specifically expressed in these neurons and both behavioral and electrophysiological consequences determined. The additional advantage offered by the whole cell configuration allows dialysis of the CaP soma with agents that can potentially alter vesicle recycling, such as clostridial toxins and calcium buffers. Due to the short distance between the soma and muscle, diffusion should occur well within the time frame of recordings. The potential of this preparation has only begun to be tapped. The transparency of the fish at this age and superficial location of synapses also facilitates use of optical tools (Fetcho and O'Malley, 1997; Fetcho and Higashijima, 2004). We have been very successful in measuring of endo and exocytosis in living fish using FM dyes and genetic indicators such as Synaptophluorin (Li et al., 2003). Additionally, fluorescent conjugated toxins can be used to label synaptic proteins for imaging of live fish (Ibanez-Tallon et al., 2004). Given the simplicity of this preparation it holds great promise for future study.

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		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
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<td>Pneumatic transducer tester</td>
<td>&nbsp;</td>
<td>Fluke Biomedical Instruments</td>
<td>DPM1B</td>
<td>&nbsp;</td>
<tr>
<td>0.002 x 3 inch tungsten rod</td>
<td>&nbsp;</td>
<td>A-M Systems Inc</td>
<td>715000</td>
<td>&nbsp;</td>
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<td>Sylgard 184 Elastomer</td>
<td>&nbsp;</td>
<td>Dow Corning Corp.</td>
<td>&nbsp;</td>
<td>The thickness of application will affect the DIC optics</td>
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paired patch clamp recordings from motor-neuron and target skeletal muscle in zebrafish

Larval zebrafish represent the first vertebrate model system to allow simultaneous patch clamp recording from a spinal motor-neuron and target muscle. This is a direct consequence of the accessibility to both cell types and ability to visually distinguish the single segmental CaP motor-neuron on the basis of morphology and location. This video demonstrates the microscopic methods used to identify a CaP motor-neuron and target muscle cells as well as the methodologies for recording from each cell type. Identification of the CaP motor-neuron type is confirmed by either dye filling or by the biophysical features such as action potential waveform and cell input resistance. Motor-neuron recordings routinely last for one hour permitting long-term recordings from multiple different target muscle cells. Control over the motor-neuron firing pattern enables measurements of the frequency-dependence of synaptic transmission at the neuromuscular junction. Owing to a large quantal size and the low noise provided by whole cell voltage clamp, all of the unitary events can be resolved in muscle. This feature permits study of basic synaptic properties such as release properties, vesicle recycling, as well as synaptic depression and facilitation. The advantages offered by this in vivo preparation eclipse previous neuromuscular model systems studied wherein the motor-neurons are usually stimulated by extracellular electrodes and the muscles are too large for whole cell patch clamp. The zebrafish preparation is amenable to combining electrophysiological analysis with a wide range of approaches including transgenic lines, morpholino knockdown, pharmacological intervention and in vivo imaging. These approaches, coupled with the growing number of neuromuscular disease models provided by mutant lines of zebrafish, open the door for new understanding of human neuromuscular disorders.

Watch this Scientific Journal Video about Paired Patch Clamp Recordings from Motor-neuron and Target Skeletal Muscle in Zebrafish at JoVE.com

Paired Patch Clamp Recordings from Motor-neuron and Target Skeletal Muscle in Zebrafish

Larval zebrafish represent the first vertebrate model system to allow simultaneous patch clamp recording from a spinal motor-neuron and target skeletal muscle. This video demonstrates the microscopic methods used to identify a segmental CaP motor-neuron and target muscle cells as well as the methodologies for recording from each cell type.

Larval zebrafish represent the first vertebrate model system to allow simultaneous patch clamp recording from a spinal motor-neuron and target muscle.  ...

paired-patch-clamp-recordings-from-motor-neuron-target-skeletal

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Neuroscience

17.0K Views.  Oregon Health and Sciences University. Larval zebrafish represent the first vertebrate model system to allow simultaneous patch clamp recording from a spinal motor-neuron and target skeletal muscle. This video demonstrates the microscopic methods used to identify a segmental CaP motor-neuron and target muscle cells as well as the methodologies for recording from each cell type.

Video: Paired Patch Clamp Recordings from Motor-neuron and Target Skeletal Muscle in Zebrafish

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 ...

Patch Clamp Recordings in Inner Ear Hair Cells Isolated from Zebrafish

Patch clamp analyses of the voltage-gated channels in sensory hair cells isolated from a variety of species have been described previously1-4 but this video represents the first application of those techniques to hair cells from zebrafish. Here we demonstrate a method to isolate healthy, intact hair cells from all of the inner ear end-organs: saccule, lagena, utricle and semicircular canals. Further, we demonstrate the diversity in hair cell size and morphology and give an example of the kinds of patch clamp recordings that can be obtained. The advantage of the use of this zebrafish model system over others stems from the availability of zebrafish mutants that affect both hearing and balance. In combination with the use of transgenic lines and other techniques that utilize genetic analysis and manipulation, the cell isolation and electrophysiological methods introduced here should facilitate greater insight into the roles hair cells play in mediating these sensory modalities.

The purpose of this video is to demonstrate procedures for obtaining healthy, intact hair cells from the inner ear organs of adult zebrafish and then using them for patch clamp studies aimed at characterizing the biophysical properties of their voltage-gated channels.

Patch  clamp analyses of the voltage-gated channels in sensory hair cells isolated  from a variety of species have been described previously1-4 but this  ...

F1FO ATPase Vesicle Preparation and Technique for Performing Patch Clamp Recordings of Submitochondrial Vesicle Membranes

Mitochondria are involved in many important cellular functions including metabolism, survival1, development and, calcium signaling2. Two of the most important mitochondrial functions are related to the efficient production of ATP, the energy currency of the cell, by oxidative phosphorylation, and the mediation of signals for programmed cell death3.
The enzyme primarily responsible for the production of ATP is the F1FO-ATP synthase, also called ATP synthase4-5. In recent years, the role of mitochondria in apoptotic and necrotic cell death has received considerable attention. In apoptotic cell death, BCL-2 family proteins such as Bax enter the mitochondrial outer membrane, oligomerize and permeabilize the outer membrane, releasing pro-apoptotic factors into the cytosol6. In classic necrotic cell death, such as that produced by ischemia or excitotoxicity in neurons, a large, poorly regulated increase in matrix calcium contributes to the opening of an inner membrane pore, the mitochondrial permeability transition pore or mPTP. This depolarizes the inner membrane and causes osmotic shifts, contributing to outer membrane rupture, release of pro-apoptotic factors, and metabolic dysfunction. Many proteins including Bcl-xL7 interact with F1FO ATP synthase, modulating its function. Bcl-xL interacts directly with the beta subunit of F1FO ATP synthase, and this interaction decreases a leak conductance within the F1FOATPasecomplex, increasing the net transport of H+ by F1FO during F1FO ATPase activity8 and thereby increasing mitochondrial efficiency. To study the activity and modulation of the ATP synthase, we isolated from rodent brain submitochondrial vesicles (SMVs) containing F1FO ATPase. The SMVs retain the structural and functional integrity of the F1FO ATPase as shown in Alavian et al. Here, we describe a method that we have used successfully for the isolation of SMVs from rat brain and we delineate the patch clamp technique to analyze channel activity (ion leak conductance) of the SMVs.

F1FO ATPase Vesicle Preparation and Technique for Performing Patch Clamp Recordings of Submitochondrial Vesicle Membranes

A method to isolate submitochondrial vesicles enriched in F1FO ATP synthase complexes from rat brain is described. These vesicles allow the study of the activity of F1FO ATPase complex and its modulation using the technique of patch clamp recording.

Mitochondria are involved in many important cellular  functions including metabolism, survival1, development and, calcium signaling2. Two of the most ...

Isolation of Sensory Neurons of Aplysia californica for Patch Clamp Recordings of Glutamatergic Currents

The marine gastropod mollusk Aplysia californica has a venerable history as a model of nervous system function, with particular significance in studies of learning and memory. The typical preparations for such studies are ones in which the sensory and motoneurons are left intact in a minimally dissected animal, or a technically elaborate neuronal co-culture of individual sensory and motoneurons. Less common is the isolated neuronal preparation in which small clusters of nominally homogeneous neurons are dissociated into single cells in short term culture. Such isolated cells are useful for the biophysical characterization of ion currents using patch clamp techniques, and targeted modulation of these conductances. A protocol for preparing such cultures is described. The protocol takes advantage of the easily identifiable glutamatergic sensory neurons of the pleural and buccal ganglia, and describes their dissociation and minimal maintenance in culture for several days without serum.

Isolation of Sensory Neurons of Aplysia californica for Patch Clamp Recordings of Glutamatergic Currents

We describe the dissection of the nervous system of the marine sea hare Aplysia after anesthesia, the isolation of neurons for short term-tissue culture, and recordings of single cell ion currents via the patch clamp technique.

The marine gastropod mollusk Aplysia californica has a venerable  history as a model of nervous system function, with particular significance in  studies ...

Patch Clamp Recordings from Embryonic Zebrafish Mauthner Cells

Mauthner cells (M-cells) are large reticulospinal neurons located in the hindbrain of teleost fish. They are key neurons involved in a characteristic behavior known as the C-start or escape response that occurs when the organism perceives a threat. The M-cell has been extensively studied in adult goldfish where it has been shown to receive a wide range of excitatory, inhibitory and neuromodulatory signals1. We have been examining M-cell activity in embryonic zebrafish in order to study aspects of synaptic development in a vertebrate preparation. In the late 1990s Ali and colleagues developed a preparation for patch clamp recording from M-cells in zebrafish embryos, in which the CNS was largely intact2,3,4. The objective at that time was to record synaptic activity from hindbrain neurons, spinal cord neurons and trunk skeletal muscle while maintaining functional synaptic connections within an intact brain-spinal cord preparation. This preparation is still used in our laboratory today. To examine the mechanisms underlying developmental synaptic plasticity, we record excitatory (AMPA and NMDA-mediated)5,6 and inhibitory (GABA and glycine) synaptic currents from developing M-cells. Importantly, this unique preparation allows us to return to the same cell (M-cell) from preparation to preparation to carefully examine synaptic plasticity and neuro-development in an embryonic organism. The benefits provided by this preparation include 1) intact, functional synaptic connections onto the M-cell, 2) relatively inexpensive preparations, 3) a large supply of readily available embryos 4) the ability to return to the same cell type (i.e. M-cell) in every preparation, so that synaptic development at the level of an individual cell can be examined from fish to fish, and 5) imaging of whole preparations due to the transparent nature of the embryos.

We have developed an intact brain-spinal cord preparation to record and monitor electrical activity via patch clamp recording from the Mauthner neurons and other reticulospinal cells in zebrafish embryos. Thus, we are able to record excitatory and inhibitory synaptic currents, voltage-gated channel activity and action potentials from key neurons in a developing embryo.

Mauthner cells (M-cells) are large  reticulospinal neurons located in the hindbrain of teleost fish. They are key  neurons involved in a characteristic ...

Whole-cell Patch-clamp Recordings from Morphologically- and Neurochemically-identified Hippocampal Interneurons

GABAergic inhibitory interneurons play a central role within neuronal circuits of the brain. Interneurons comprise a small subset of the neuronal population (10-20%), but show a high level of physiological, morphological, and neurochemical heterogeneity, reflecting their diverse functions. Therefore, investigation of interneurons provides important insights into the organization principles and function of neuronal circuits. This, however, requires an integrated physiological and neuroanatomical approach for the selection and identification of individual interneuron types. Whole-cell patch-clamp recording from acute brain slices of transgenic animals, expressing fluorescent proteins under the promoters of interneuron-specific markers, provides an efficient method to target and electrophysiologically characterize intrinsic and synaptic properties of specific interneuron types. Combined with intracellular dye labeling, this approach can be extended with post-hoc morphological and immunocytochemical analysis, enabling systematic identification of recorded neurons. These methods can be tailored to suit a broad range of scientific questions regarding functional properties of diverse types of cortical neurons.

Cortical networks are controlled by a small, but diverse set of inhibitory interneurons. Functional investigation of interneurons therefore requires targeted recording and rigorous identification. Described here is a combined approach involving whole-cell recordings from single or synaptically-coupled pairs of neurons with intracellular labeling, post-hoc morphological and immunocytochemical analysis.

GABAergic inhibitory interneurons play a central role within neuronal circuits of the brain. Interneurons comprise a small subset of the neuronal ...

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 ...

Electrophysiological and Morphological Characterization of Neuronal Microcircuits in Acute Brain Slices Using Paired Patch-Clamp Recordings

The combination of patch clamp recordings from two (or more) synaptically coupled neurons (paired recordings) in acute brain slice preparations with simultaneous intracellular biocytin filling allows a correlated analysis of their structural and functional properties. With this method it is possible to identify and characterize both pre- and postsynaptic neurons by their morphology and electrophysiological response pattern. Paired recordings allow studying the connectivity patterns between these neurons as well as the properties of both chemical and electrical synaptic transmission. Here, we give a step-by-step description of the procedures required to obtain reliable paired recordings together with an optimal recovery of the neuron morphology. We will describe how pairs of neurons connected via chemical synapses or gap junctions are identified in brain slice preparations. We will outline how neurons are reconstructed to obtain their 3D morphology of the dendritic and axonal domain and how synaptic contacts are identified and localized. We will also discuss the caveats and limitations of the paired recording technique, in particular those associated with dendritic and axonal truncations during the preparation of brain slices because these strongly affect connectivity estimates. However, because of the versatility of the paired recording approach it will remain a valuable tool in characterizing different aspects of synaptic transmission at identified neuronal microcircuits in the brain.

Patch-clamp recordings and simultaneous intracellular biocytin filling of synaptically coupled neurons in acute brain slices allow a correlated analysis of their structural and functional properties. The aim of this protocol is to describe the essential technical steps of electrophysiological recording from neuronal microcircuits and their subsequent morphological analysis.

The combination of patch clamp recordings from two (or more) synaptically coupled neurons (paired recordings) in acute brain slice preparations with ...

Whole-cell Patch-clamp Recordings in Brain Slices

Whole-cell patch-clamp recording is an electrophysiological technique that allows the study of the&#160;electrical properties of a substantial part of the neuron. In this configuration, the micropipette is in tight contact with the cell membrane, which prevents current leakage and thereby provides more accurate ionic current measurements than the previously used intracellular sharp electrode recording method. Classically, whole-cell recording can be performed on neurons in various types of preparations, including cell culture models, dissociated neurons, neurons in brain slices, and in intact anesthetized or awake animals. In summary, this technique has immensely contributed to the understanding of passive and active biophysical properties of excitable cells. A major advantage of this technique is that it provides information on how specific manipulations (e.g., pharmacological, experimenter-induced plasticity) may alter specific neuronal functions or channels in real-time. Additionally, significant opening of the plasma membrane allows the internal pipette solution to freely diffuse into the cytoplasm, providing means for introducing drugs, e.g., agonists or antagonists of specific intracellular proteins, and manipulating these targets without altering their functions in neighboring cells. This article will focus on whole-cell recording performed on neurons in brain slices,&#160;a preparation that has the advantage of recording neurons in relatively well preserved brain circuits, i.e., in a physiologically relevant context. In particular,&#160;when combined with appropriate pharmacology, this technique is a powerful tool allowing identification of specific neuroadaptations that occurred following any type of experiences, such as learning, exposure to drugs of abuse, and stress. In summary, whole-cell patch-clamp recordings in brain slices provide means to measure in ex vivo preparation long-lasting changes in neuronal functions that have developed in intact awake animals.

This protocol describes basic procedural steps for performing whole-cell patch-clamp recordings. This technique allows the study of&#160;the electrical behavior of neurons, and when performed in brain slices, allows the assessment of various neuronal functions from neurons that are still integrated in relatively well preserved brain circuits.

Whole-cell patch-clamp recording is an electrophysiological technique that allows the study of the&#160;electrical properties of a substantial part of the ...

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 ...