Die Autoren danken Dr. Candace Hsieh für Anregungen und Unterstützung danken, mit bildgebenden Verfahren und Dr. Doris Wu für Kompetenz auf chick Innenohr Anatomie während der frühen Embryogenese. Diese Arbeit wurde von der NSF IOS-0642346, NIH T32-DC010775, NIH T32-GM008620, NIH R01-DC010796 und DOE GAANN P200A120165 unterstützt.

Ein. Bereiten Sie die folgenden Dissection Tools und Reagenzien <ul><li> Künstlicher zerebrospinaler Flüssigkeit (ACSF; 130 mM NaCl, 3 mM KCl, 1,2 mM KH 2 PO 4, 20 mM NaHCO 3, 3 mM HEPES, 10 mM Glucose, 2 mM CaCl 2, 1,3 mM MgSO 4) kontinuierlich mit 95% O infundiert 2/5% CO 2 bei Raumtemperatur. Infusionslösung, zu 2/3 eine 500 ml Nalgene Weithals-Glas mit einem Loch im Deckel gebohrt füllen. Tank wird über einen Schlauch zu einem Glasfuß Gasspüler, der die aCSF dringt durch das Loch im Glas Deckel befestigt werden. Passen Druck, um einen konstanten Strom von Blasen, die etwa 1/3 der Flüssigkeit zu erreichen, sind aber nicht stark genug, um zu bewirken spritzt über die Felge zu erhalten. Submerge 5 ml Glasampullen (bis 6) in das Glas zu Nalgene einzelnen Proben voneinander und aus dem Gasstrom Turbulenzen zu trennen. ACSF sollte mindestens 20 Minuten vor jedem Gewebe Inkubationszeit Sauerstoff versorgt werden. </li><li> Kleine Silikon-Dissektion Teller (35 mm x 10mm Petri beschichtet mit Sylgard Elastomere Kit) mit zwei Dissektion Stifte in kleine sechseckige Polystyrol gelegt (47 mm unten) Wiegeschiffchen. </li><li> Zwei feinen Spitze-Zange, eine gekrümmte Spitze-Zange, einer 50 ml-Becher, und einen Behälter für das Tissue Abfall. </li><li> Gezogen Glasmikropipette (1,2 OD / 0,9 ID) zerbrochen zu etwa 20-50 um die Öffnung an der Spitze und mit Rhodamin Dextran Amin (RDA, MW = 3.000, Invitrogen) in einer 6,25% igen Lösung mit 0,4% Triton X-100 in PBS . Bringen Sie durch feine Schlauch an picospritzer und Mikromanipulator stabilisieren. </li></ul> 2. Micro-Dissektion Basilar Papilla am E8 4,5 Reveal <ol><li> Mit gebogenen Pinzette, schneiden E8 Embryo direkt unter dem Hirnstamm, indem Kopf direkt auf silikonbeschichteten Dissektion Gericht in Wiegeschiffchen. </li><li> Mit Dissektion Stifte, positionieren Sie den Kopf mit einem ventral so das Ohr auf der Seite von Interesse ist leicht sichtbar, geneigt der Kopf leicht nach dorsal und zeigt 10-30 Grad weg von center (Abbildung 2A). Unmittelbar sichern den Kopf mit Stiften. Wenn bilateralen Ablaufverfolgung gewünscht wird, in der Mitte der Kopf bei 0 Grad, oder eine vollständige ventral, so dass beide Seiten zugegriffen werden kann. Ähnliches gilt bei einer linksseitigen Injektion, sichern den Kopf bei -10 bis -30 Grad von der Mitte, so dass die linke Seite zugänglich ist. </li><li> Mit dem 50-ml-Becher, übertragen 30 ml des oxygenierten aCSF in die Schüssel, voll Eintauchen des Gewebes. </li><li> Fassen und schälen sich den Unterkiefer mit feiner Spitze Pinzette, dann entfernen Sie das untere Augenlid auf der Seite von Interesse. </li><li> Entfernen Sie den darüberliegenden Gefäßgewebe, einschließlich aller übrigen Gaumen und Kehle. Diese weichen Geweben sollte abzuschälen enthüllt die glatte Oberfläche zu entwickeln Chondrocranium mit den unverwechselbaren Vertebralarterien an seiner Oberfläche. Zu diesem Zeitpunkt sollte die charakteristischen weißen otoconial Masse sichtbar sein. </li><li> Vorsichtig zu sezieren die Haut um den äußeren Gehörgang, Knorpel des Kiefergelenks und des Mittelohrs, während die inner Ohr intakt. Verwenden Sie die Pinzette vorsichtig weggeschnitten diese knorpeligen Strukturen. </li><li> Entfernen Vertebralarterien und Bündelung Blut mit einem sanften Kehrbewegung mit den feinen Pinzette Tipps. Blut kann darüber hinwegtäuschen, Ansicht und Koagulation kann die Injektionspipette Öffnung stecken. </li><li> Das Cochlea Kanal mit benachbarten Sinnesepithel (basilaris Papilla) und akustische Ganglion liegt direkt unterhalb der Chondrocranium 6 und kann als länglicher fingerartigen Vorsprung aus dem Innenohr ventral, mit der am weitesten distalen Spitze (Apex) in der Nähe des vorderen visualisiert Mittellinie 5. Es kann eine kleine Ansammlung von Blut (rote) werden aus der Dissektion und / oder otolithic Verkalkungen (weiß) im Scheitelpunkt des Cochlea Kanal (2B), die in Visualisierung unterstützen kann. An der Spitze ist die lagenar Makula, dachte eine sensorische Patch der vestibulären Funktion 7,8 sein. </li></ol> 3. Selektive Markierung von CN VIII Auditory Fibers <ol><li&gt; Legen Sie die Injektionspipette in der Nähe des Embryos Fläche an der Ductus cochlearis und basiläre Papille Region. </li><li> Langsam senken die Mikropipette zum ersten Punktion der Schädel. Diese Oberkopf ist dünner als die Umgebung und erfordert weniger Kraftaufwand zu durchdringen. Die Mikropipette sollte nun im Inneren des Ductus cochlearis sein. Optional: eine kleine Injektion von Tracing Farbstoff kann hier gemacht werden, um in die Visualisierung der basilaris Papilla unterstützen. </li><li> Ohne Neupositionierung der Mikropipette weiter senken, bis es nur Verstöße gegen die tief Rand des Ductus cochlearis (Abbildung 1). Durchführen einer Injektion und wiederholen hier in mehreren Bereichen entlang der Länge des basilaren Papille (2C, 2D) mit Ausnahme des am meisten proximalen Spitze, wo der vestibulären Lagena befindet. Mit dem picospritzer zwischen 10-30 psi eingestellt ist, werden mehrere Injektionen gemacht. Das Volumen des injizierten Farbstoff Fluids variiert und hängt von dem Ausmaß der gewünschten Etikettierung. Jede Injektion sollte in einem Fluoreszenzfarbstoff-la führenBeled Ort von etwa 200 bis 400 Mikrometer Durchmesser (2D). </li><li> Sobald die Injektion abgeschlossen ist, verwenden Pinzette, um die Probe oberhalb des Hirnstamms durchschneiden und verwenden Sie eine Pipette, um den kaudalen Teil in einen kleinen Topf legen im Behälter aCSF kontinuierlich mit 95% O 2/5% CO 2 durchströmt. </li><li> Für jedes Embryo erlauben 20-30 min zur Farbstoffübertragung, abhängig vom Abstand der zentralen Tracing gewünscht. </li><li> Entfernen Gewebe und die Vorbereitungen für histologische Schnitte. In dem hier gezeigten Beispiel wird Gewebe in 4% Paraformaldehyd (in 1X PBS) über Nacht, 30% Saccharose (in 1X PBS) über Nacht eingetaucht. </li></ol> 4. Gegenfärbung und Analyse <ol><li> Gegenfärbung ist nützlich, um zu helfen orient der Beobachter an anatomische Lage sowie zu identifizieren bestimmte Regionen von Interesse. Eine wirksame Gegenfärbung in dieser Zubereitung ist Neurofilament Immunmarkierung (Figuren 1, 3B, 3E), die stark l MitAbels Axonen und ermöglicht Abgrenzung der axonalen Bahnen im ZNS. </li><li> Analyse sollte während der markierten Region durchgeführt werden, wie die Vorsprünge können mehrere hundert Mikrometer oder mehr entlang der Achse rostrokaudalen erstrecken. Einige Beispiele für grundlegende Untersuchungen sind: Targeting Fehlerraten, Timing und / oder Veränderungen der Divergenz der Projektionsmuster. RDA-markierte Axone visualisiert im peripheren und zentralen Nervensystems mit hoher Auflösung (3A, 3D). </li></ol>

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Studien der frühen Entwicklung des VIII. Nerven wurden zum Teil wegen der Schwierigkeiten bei der Ermittlung embryonalen Axone aus mehreren verschiedenen Ganglien begrenzt. Mehrere Studien haben die molekularen Signale Führung auditorischen und vestibulären sensorischen Zellen und Ganglienzellen Schicksale während der frühen Entwicklung, 5,11,12 erforscht, aber die Prozesse, die die zentrale Innervation müssen noch bestimmt werden. Berichte von akustischen Ganglienzellen Projektionen beschreiben typisch...

<table border="1"><tbody><tr><td> Name des Reagenz / Material </td><td> Firma </td><td> Catalog Number </td><td> Kommentare </td></tr><tr><td> Polystyrol Wiegen Dish </td><td> Fisher Scientific </td><td> 02-202-101 </td><td></td></tr><tr><td> Petrischale, 35 X 10 mm </td><td> Fisher Scientific </td><td> 50820644 </td><td> Verwenden, um Silikon-Dissektion Gericht zu machen </td></tr><tr><td> Sylgard Silikon-Elastomer Kit </td><td> World Precision Instruments </td><td> SYLG184 </td><td> Coat Petri zu machen Dissektion Gericht </td></tr><tr><td> Dissection Pins </td><td> Verschiedene </td><td></td><td> Hält Embryo im Ort während der Präparation </td></tr><tr><td> NaCL </td><td> Verschiedene </td><td></td><td> Teil aCSF Rezept </td></tr><tr><td> KCl </td><td> Verschiedene </td><td></td><td> Teil aCSF Rezept </td&gt; </tr><tr><td> KH 2 PO 4 </td><td> Verschiedene </td><td></td><td> Teil aCSF Rezept </td></tr><tr><td> NaHCO 3 </td><td> Verschiedene </td><td></td><td> Teil aCSF Rezept </td></tr><tr><td> Glucose </td><td> Verschiedene </td><td></td><td> Teil aCSF Rezept </td></tr><tr><td> CaCl 2 </td><td> Verschiedene </td><td></td><td> Teil aCSF Rezept </td></tr><tr><td> MgSO 4 </td><td> Verschiedene </td><td></td><td> Teil aCSF Rezept </td></tr><tr><td> Behälter für aCSF. Vorschlagen transluzenten Weithals-Nalgene Flasche, 500 ml (16 oz) mit Deckel. </td><td> CPLabSafety </td><td> QP-PLC-03717 </td><td> Bohrloch Öffnung an der Oberseite des Deckels für Glas bubling Stammzellen zu durchdringen Flüssigkeit </td></tr><tr><td> Leere 5 ml Glasfläschchen oder vergleichbaren transparenten Flasche </td><td> American Pharmaceutical Partners, Inc </td><td> 6332300105 </td><td&gt; während aCSF Inkubation verwenden, um Proben getrennt von einander und von der sprudelnden Strom </td></tr><tr><td> Tank von Carbogen (95% O 2/5% CO 2) durch einen Schlauch zur Waschflasche verbunden </td><td> Verschiedene </td><td></td><td> Bringen Sie durch einen Schlauch zu Glasfuß Bubbler zur Infusion in aCSF </td></tr><tr><td> Glasfuß Bubbler </td><td> Verschiedene </td><td></td><td> Um Carbogen in aCSF einzuflößen </td></tr><tr><td> Curved-Spitze Pinzette </td><td> World Precision Instruments </td><td> 501008 </td><td> Um Embryo Kopf vom Ei entfernen </td></tr><tr><td> Zwei feine Spitze Pinzette </td><td> World Precision Instruments </td><td> 501985 </td><td> Für Mikro-Dissektion </td></tr><tr><td> 50 ml Becherglas </td><td> verschiedene </td><td></td><td></td></tr><tr><td> Rhodamin Dextran Amine (RDA) </td><td> Invitrogen </td><td> verschiedene </td><td> Fluorescent Axon Tracer </td></tr><tr><td> Triton X-100 </td><td> ICN Biomedicals </td><td></td><td></td></tr><tr><td> Phosphate Buffered Saline, (1X PBS) </td><td> Verschiedene </td><td></td><td> Standard-Lab-Reagenz </td></tr><tr><td> Thin Wall Glaskapillaren 1,2 OD, 0,9 ID 4 &quot;(100 mm) Länge </td><td> World Precision Instruments </td><td> TW120F-4 </td><td> Legen Sie mit RDA. Jede Kapillare macht zwei Glasmikropipetten </td></tr><tr><td> Needle / Pipette puller </td><td> David Kopf Instruments </td><td> Modell 720 </td><td> Einstellungen verwendet: Heat 16,4, Solenoid 2,2 </td></tr><tr><td> Picospritzer </td><td> Parker Instrumentation </td><td> verschiedene </td><td> Bringen Sie durch feine Schlauch an Glasmikropipette </td></tr><tr><td> Micromanipulator </td><td> Narishige </td><td> verschiedene </td><td></td></tr><tr><td> Dissection Mikroskop mit Fluoreszenz </td><td> Verschiedene </td><td></td><td></td&gt; </tr><tr><td> 4% Paraformaldehyd </td><td> Verschiedene </td><td></td><td> Standard-Lab-Reagenz </td></tr><tr><td> anti-Neurofilament-Antikörper, optional </td><td> Millipore </td><td> AB1991 </td><td> Folgen histologischen Protokoll vom Hersteller empfohlen </td></tr><tr><td> Kryostat und zugehörige Materialien für das Schneiden </td><td> Leica </td><td> verschiedene </td><td></td></tr><tr><td> Epifluoreszenz-Mikroskop zum Abbilden </td><td> Zeiss, verschiedene </td><td></td><td></td></tr></tbody></table>

selective tracing of auditory fibers in the avian embryonic vestibulocochlear nerve

Die embryonale Küken ist ein weit verbreitetes Modell für die Untersuchung der peripheren und zentralen Ganglienzellen Projektionen. Im auditorischen System würde selektive Markierung von auditiven Axone innerhalb des VIII. Hirnnerven verbessern das Studium der zentralen auditorischen Schaltungsentwicklung. Dieser Ansatz ist schwierig, weil mehrere Sinnesorgane des Innenohrs der VIII. Nerven 1 beitragen. Darüber hinaus haben Markern, die zuverlässig unterscheiden auditive gegenüber vestibulären Gruppen von Axonen innerhalb der Vogelgrippe VIII. Nerven noch nicht identifiziert werden. Auditive und vestibulären Wege nicht funktional in frühen Embryonen unterschieden werden, als sensorische hervorgerufenen Reaktionen nicht vorhanden sind, bevor die Schaltungen ausgebildet sind. Zentral vorstehenden VIII. Nervenaxone haben in einigen Studien verfolgt worden, aber auditiven Axon Markierung wurde durch Markierung von anderen VIII. Nerven Bauteile 2,3 begleitet. Hier beschreiben wir eine Methode zur anterograde Tracing von der akustischen ganglion selektiv label auditiven Axone innerhalb des sich entwickelnden VIII. Nerven. Erste, nach teilweiser Durchtrennung des vorderen Schädelbereich des 8-tägiger Hühnerembryos in sauerstoffhaltigen künstliche Zerebrospinalflüssigkeit eingetaucht wird der Kanal durch Cochlea anatomischen Landmarken identifiziert. Als Nächstes wird ein feiner gezogen Glasmikropipette positioniert, um eine kleine Menge an Rhodamin Dextran Amin in den Kanal und benachbart tiefen Bereich, wo die akustischen Ganglienzellen befinden injizieren. Innerhalb 30 Minuten nach der Injektion werden auditive Axone zentral in den Hinterhirn zurückverfolgt und können später visualisiert werden nach histologischen Vorbereitung. Diese Methode liefert ein nützliches Werkzeug für Entwicklungsstudien der peripheren zum zentralen auditorischen Schaltung Bildung.

Die Komponenten der VIII. Nerv und der Anatomie des Nerven selbst sind komplex und gewundenen (Figuren 1, 3). Durch selektives Tracing Fasern aus akustischen Ganglienzellen können Segmente des VIII. Nerven sowie primären auditorischen Afferenzen im Hirnstamm sauber zurückverfolgt werden und sich von ihren vestibulären Gegenstücke (Abbildungen 2, 3). Ebenso könnte diese Technik verwendet, um periphere Vorsprünge der akustischen Ganglienzellen (3G) studieren oder m...

Watch this Scientific Journal Video about Selective Tracing of Auditory Fibers in the Avian Embryonic Vestibulocochlear Nerve at JoVE.com

Selective Tracing of Auditory Fibers in the Avian Embryonic Vestibulocochlear Nerve

Hier beschreiben wir eine Technik, die von Mikrodissektion Fluoreszenzfarbstoff Injektion in den akustischen Ganglion frühen Hühnerembryonen zur selektiven Rückverfolgung von auditorischen Axon Fasern im Nerv und Rautenhirn gefolgt.

Selektive Tracing von Auditory Fibers im Avian Embryonale vestibulocochlearis

The embryonic chick is a widely used model for the study of peripheral and central ganglion cell projections. In the auditory system, selective labeling ...

selective-tracing-auditory-fibers-avian-embryonic-vestibulocochlear

Research

JoVE Journal

Neuroscience

9.1K Aufrufe.  University of California, Irvine. Hier beschreiben wir eine Technik, die von Mikrodissektion Fluoreszenzfarbstoff Injektion in den akustischen Ganglion frühen Hühnerembryonen zur selektiven Rückverfolgung von auditorischen Axon Fasern im Nerv und Rautenhirn gefolgt.

Serie: Selective Tracing of Auditory Fibers in the Avian Embryonic Vestibulocochlear Nerve

Tissue Preparation and Immunostaining of Mouse Sensory Nerve Fibers Innervating Skin and Limb Bones

Detection and primary processing of physical, chemical and thermal sensory stimuli by peripheral sensory nerve fibers is key to sensory perception in animals and humans. These peripheral sensory nerve fibers express a plethora of receptors and ion channel proteins which detect and initiate specific sensory stimuli. Methods are available to characterize the electrical properties of peripheral sensory nerve fibers innervating the skin, which can also be utilized to identify the functional expression of specific ion channel proteins in these fibers. However, similar electrophysiological methods are not available (and are also difficult to develop) for the detection of the functional expression of receptors and ion channel proteins in peripheral sensory nerve fibers innervating other visceral organs, including the most challenging tissues such as bone. Moreover, such electrophysiological methods cannot be utilized to determine the expression of non-excitable proteins in peripheral sensory nerve fibers. Therefore, immunostaining of peripheral/visceral tissue samples for sensory nerve fivers provides the best possible way to determine the expression of specific proteins of interest in these nerve fibers. So far, most of the protein expression studies in sensory neurons have utilized immunostaining procedures in sensory ganglia, where the information is limited to the expression of specific proteins in the cell body of specific types or subsets of sensory neurons. Here we report detailed methods/protocols for the preparation of peripheral/visceral tissue samples for immunostaining of peripheral sensory nerve fibers. We specifically detail methods for the preparation of skin or plantar punch biopsy and bone (femur) sections from mice for immunostaining of peripheral sensory nerve fibers. These methods are not only key to the qualitative determination of protein expression in peripheral sensory neurons, but also provide a quantitative assay method for determining changes in protein expression levels in specific types or subsets of sensory fibers, as well as for determining the morphological and/or anatomical changes in the number and density of sensory fibers during various pathological states. Further, these methods are not confined to the staining of only sensory nerve fibers, but can also be used for staining any types of nerve fibers in the skin, bones and other visceral tissue.

Immunocytochemical identification of peripheral sensory nerve fiber subtypes (and detection of protein expression therein) are key to the understanding of molecular mechanisms underlying peripheral sensation. Here we describe methods for preparation of peripheral/visceral tissue samples, such as skin and limb bones, for specific immunostaining of peripheral sensory nerve fibers.

Tissue Vorbereitung und Immunfärbung von Maus sensorischen Nervenfasern innervieren Haut und Limb Bones

Detection and primary processing of physical, chemical and thermal sensory stimuli by peripheral sensory nerve fibers is key to sensory perception in ...

Forschung

Neurowissenschaften

A Lightweight, Headphones-based System for Manipulating Auditory Feedback in Songbirds

Experimental manipulations of sensory feedback during complex behavior have provided valuable insights into the computations underlying motor control and sensorimotor plasticity1. Consistent sensory perturbations result in compensatory changes in motor output, reflecting changes in feedforward motor control that reduce the experienced feedback error. By quantifying how different sensory feedback errors affect human behavior, prior studies have explored how visual signals are used to recalibrate arm movements2,3 and auditory feedback is used to modify speech production4-7. The strength of this approach rests on the ability to mimic naturalistic errors in behavior, allowing the experimenter to observe how experienced errors in production are used to recalibrate motor output.
Songbirds provide an excellent animal model for investigating the neural basis of sensorimotor control and plasticity8,9. The songbird brain provides a well-defined circuit in which the areas necessary for song learning are spatially separated from those required for song production, and neural recording and lesion studies have made significant advances in understanding how different brain areas contribute to vocal behavior9-12. However, the lack of a naturalistic error-correction paradigm - in which a known acoustic parameter is perturbed by the experimenter and then corrected by the songbird - has made it difficult to understand the computations underlying vocal learning or how different elements of the neural circuit contribute to the correction of vocal errors13.
The technique described here gives the experimenter precise control over auditory feedback errors in singing birds, allowing the introduction of arbitrary sensory errors that can be used to drive vocal learning. Online sound-processing equipment is used to introduce a known perturbation to the acoustics of song, and a miniaturized headphones apparatus is used to replace a songbird's natural auditory feedback with the perturbed signal in real time. We have used this paradigm to perturb the fundamental frequency (pitch) of auditory feedback in adult songbirds, providing the first demonstration that adult birds maintain vocal performance using error correction14. The present protocol can be used to implement a wide range of sensory feedback perturbations (including but not limited to pitch shifts) to investigate the computational and neurophysiological basis of vocal learning.

We describe the design and assembly of miniaturized headphones suitable for replacing a songbird&#x2019;s natural auditory feedback with a manipulated acoustic signal. Online sound processing hardware is used to manipulate song output, introduce real-time errors in auditory feedback via the headphones, and drive vocal motor learning.

Ein Leichtes, Kopfhörer-basierte System zur Manipulation Auditory Feedback in Songbirds

Experimental manipulations of sensory feedback during complex behavior have provided valuable insights into the computations underlying motor control and ...

Optogenetic Stimulation of the Auditory Nerve

Direct electrical stimulation of spiral ganglion neurons (SGNs) by cochlear implants (CIs) enables open speech comprehension in the majority of implanted deaf subjects1-6. Nonetheless, sound coding with current CIs has poor frequency and intensity resolution due to broad current spread from each electrode contact activating a large number of SGNs along the tonotopic axis of the cochlea7-9. Optical stimulation is proposed as an alternative to electrical stimulation that promises spatially more confined activation of SGNs and, hence, higher frequency resolution of coding. In recent years, direct infrared illumination of&#160;the cochlea has been used to evoke responses in the auditory nerve10. Nevertheless it requires higher energies than electrical stimulation10,11 and uncertainty remains as to the underlying mechanism12. Here we describe a method based on optogenetics to stimulate SGNs with low intensity blue light, using transgenic mice with neuronal expression of channelrhodopsin 2 (ChR2)13 or virus-mediated expression of the ChR2-variant CatCh14. We used micro-light emitting diodes (&#181;LEDs) and fiber-coupled lasers to stimulate ChR2-expressing SGNs through a small artificial opening (cochleostomy) or the round window. We assayed the responses by scalp recordings of light-evoked potentials (optogenetic auditory brainstem response: oABR) or by microelectrode recordings from the auditory pathway and compared them with acoustic and electrical stimulation.

Cochlear implants (CIs) enable hearing by direct electrical stimulation of the auditory nerve. However, poor frequency and intensity resolution limits the quality of hearing with CIs. Here we describe optogenetic stimulation of the auditory nerve in mice as an alternative strategy for auditory research and developing future CIs.

Optogenetische Stimulation des Hörnervs

Direct electrical stimulation of spiral ganglion neurons (SGNs) by cochlear implants (CIs) enables open speech comprehension in the majority of implanted ...

Conditional Genetic Transsynaptic Tracing in the Embryonic Mouse Brain

Anatomical path tracing is of pivotal importance to decipher the relationship between brain and behavior. Unraveling the formation of neural circuits during embryonic maturation of the brain however is technically challenging because most transsynaptic tracing methods developed to date depend on stereotaxic tracer injection. To overcome this problem, we developed a binary genetic strategy for conditional genetic transsynaptic tracing in the mouse brain. Towards this end we generated two complementary knock-in mouse strains to selectively express the bidirectional transsynaptic tracer barley lectin (BL) and the retrograde transsynaptic tracer Tetanus Toxin fragment C from the ROSA26 locus after Cre-mediated recombination. Cell-specific tracer production in these mice is genetically encoded and does not depend on mechanical tracer injection. Therefore our experimental approach is suitable to study neural circuit formation in the embryonic murine brain. Furthermore, because tracer transfer across synapses depends on synaptic activity, these mouse strains can be used to analyze the communication between genetically defined neuronal populations during brain development at a single cell resolution. Here we provide a detailed protocol for transsynaptic tracing in mouse embryos using the novel recombinant ROSA26 alleles. We have utilized this experimental technique in order to delineate the neural circuitry underlying maturation of the reproductive axis in the developing female mouse brain.

Capitalizing on a binary genetic strategy we provide a detailed protocol for neural circuit tracing in mice that express complementary transsynaptic tracers after Cre-mediated recombination. Because cell-specific tracer production is genetically encoded, our experimental approach is suitable to study the formation and maturation of neural circuitry during murine embryonic brain development at a single cell resolution.

Bedingte Genetische transsynaptische Tracing in der embryonalen Maus-Gehirn

Anatomical path tracing is of pivotal importance to decipher the relationship between brain and behavior. Unraveling the formation of neural circuits ...

Laser-guided Neuronal Tracing In Brain Explants

We present a technique which combines an in vitro tracer injection protocol, which uses a series of electrical and pressure pulses to increase dye uptake through electroporation in brain explants with targeted laser illumination and matching filter goggles during the procedure. The described technique of in vitro electroporation by itself yields relatively good visual control for targetting certain areas of the brain. By combining it with laser excitation of fluorescent genetic markers and their read-out through band-passing filter goggles, which can pick up the emissions of the genetically labeled cells/nuclei and the fluorescent tracing dye, a researcher can substantially increase the accuracy of injections by finding the area of interest and controlling for the dye-spread/uptake in the injection area much more efficiently. In addition, the laser illumination technique allows to study the functionality of a given neurocircuit by providing information about the type of neurons projecting to a certain area in cases where the GFP expression is linked to the type of transmitter expressed by a subpopulation of neurons.

We describe a technique to label neurons and their processes via anterograde or retrograde tracer injections into brain nuclei using an in vitro preparation. We modified an existing method of in vitro tracer electroporation by taking advantage of fluorescently labeled mouse mutants and basic optical equipment in order to increase labeling accuracy.

Lasergelenkte neuronale Tracing in Brain Explantate

We present a technique which combines an in vitro tracer injection protocol, which uses a series of electrical and pressure pulses to increase dye uptake ...

Three-dimensional Imaging and Analysis of Mitochondria within Human Intraepidermal Nerve Fibers

The goal of this protocol is to study mitochondria within intraepidermal nerve fibers. Therefore, 3D imaging and analysis techniques were developed to isolate nerve-specific mitochondria and evaluate disease-induced alterations of mitochondria in the distal tip of sensory nerves. The protocol combines fluorescence immunohistochemistry, confocal microscopy and 3D image analysis techniques to visualize and quantify nerve-specific mitochondria. Detailed parameters are defined throughout the procedures in order to provide a concrete example of how to use these techniques to isolate nerve-specific mitochondria. Antibodies were used to label nerve and mitochondrial signals within tissue sections of skin punch biopsies, which was followed by indirect immunofluorescence to visualize nerves and mitochondria with a green and red fluorescent signal respectively. Z-series images were acquired with confocal microscopy and 3D analysis software was used to process and analyze the signals. It is not necessary to follow the exact parameters described within, but it is important to be consistent with the ones chosen throughout the staining, acquisition and analysis steps. The strength of this protocol is that it is applicable to a wide variety of circumstances where one fluorescent signal is used to isolate other signals that would otherwise be impossible to study alone.

This protocol uses three-dimensional (3D) imaging and analysis techniques to visualize and quantify nerve-specific mitochondria. The techniques are applicable to other situations where one fluorescent signal is used to isolate a subset of data from another fluorescent signal.

Dreidimensionale Bildgebung und Analyse der Mitochondrien innerhalb von menschlichen Intraepidermal Nervenfasern

The goal of this protocol is to study mitochondria within intraepidermal nerve fibers. Therefore, 3D imaging and analysis techniques were developed to ...

Imaging Serotonergic Fibers in the Mouse Spinal Cord Using the CLARITY/CUBIC Technique

Long descending fibers to the spinal cord are essential for locomotion, pain perception, and other behaviors. The fiber termination pattern in the spinal cord of the majority of these fiber systems have not been thoroughly investigated in any species. Serotonergic fibers, which project to the spinal cord, have been studied in rats and opossums on histological sections and their functional significance has been deduced based on their fiber termination pattern in the spinal cord. With the development of CLARITY and CUBIC techniques, it is possible to investigate this fiber system and its distribution in the spinal cord, which is likely to reveal previously unknown features of serotonergic supraspinal pathways. Here, we provide a detailed protocol for imaging the serotonergic fibers in the mouse spinal cord using the combined CLARITY and CUBIC techniques. The method involves perfusion of a mouse with a hydrogel solution and clarification of the tissue with a combination of clearing reagents. Spinal cord tissue was cleared in just under two weeks, and the subsequent immunofluorescent staining against serotonin was completed in less than ten days. With a multi-photon fluorescent microscope, the tissue was scanned and a 3D image was reconstructed using Osirix software.

Supraspinal projections are important for pain perception and other behaviors, and serotonergic fibers are one of these fiber systems. The present study focused on the application of the combined CLARITY/CUBIC protocol to the mouse spinal cord in order to investigate the termination of these serotonergic fibers.

Imaging Serotonerge Fasern im Rückenmark der Maus Mit der CLARITY / CUBIC Technik

Long descending fibers to the spinal cord are essential for locomotion, pain perception, and other behaviors. The fiber termination pattern in the spinal ...

In Vitro Characterization of the Electrophysiological Properties of Colonic Afferent Fibers in Rats

Dysfunction of the colonic sensory nerves has been implicated in the pathophysiology of several common conditions, including functional and inflammatory bowel diseases and diabetes. Here, we describe a protocol for the in vitro characterization of the electrophysiological properties of colonic afferents in rats. The colorectum, with the intact pelvic ganglion (PG) attached, is removed from the rat; superfused with carbogenated Krebs solution in the recording chamber; and cannulated at the oral and anal ends to allow for distension. A fine nerve bundle emanating from the PG is identified, and the multiunit afferent nerve activity is recorded using a suction electrode. Distension of the colonic segment elicits gradual increases in multiunit discharge. A principal component analysis is conducted to differentiate the low-threshold, the high-threshold, and the wide-dynamic range afferent fibers. Chemical sensitivity of colonic afferents can be studied through the bath or intraluminal administration of test compounds. This protocol can be modified for application to other species, such as mice and guinea pigs, and to study the differences in the electrophysiological properties of thoracolumbar/hypogastric and lumbosacral/pelvic afferents of the descending colon in normal and pathological conditions.

In Vitro Characterization of the Electrophysiological Properties of Colonic Afferent Fibers in Rats

Abnormal sensory function underlies visceral pain and other symptoms of functional and inflammatory bowel diseases. A protocol for the electrophysiological recording of the colonic afferent nerves in an ex vivo rat colorectum preparation is presented here.

In-vitro- Charakterisierung der elektrophysiologischen Eigenschaften des Kolon afferenten Fasern in Ratten

Dysfunction of the colonic sensory nerves has been implicated in the pathophysiology of several common conditions, including functional and inflammatory ...

Retrograde Neuroanatomical Tracing of Phrenic Motor Neurons in Mice

Phrenic motor neurons are cervical motor neurons originating from C3 to C6 levels in most mammalian species. Axonal projections converge into phrenic nerves innervating the respiratory diaphragm. In spinal cord slices, phrenic motor neurons cannot be identified from other motor neurons on morphological or biochemical criteria. We provide the description of procedures for visualizing phrenic motor neuron cell bodies in mice, following intrapleural injections of cholera toxin subunit beta (CTB) conjugated to a fluorophore. This fluorescent neuroanatomical tracer has the ability to be caught up at the diaphragm neuromuscular junction, be carried retrogradely along the phrenic axons and reach the phrenic cell bodies. Two methodological approaches of intrapleural CTB delivery are compared: transdiaphragmatic versus transthoracic injections. Both approaches are successful and result in similar number of CTB-labeled phrenic motor neurons. In conclusion, these techniques can be applied to visualize or quantify the phrenic motor neurons in various experimental studies such as those focused on the diaphragm-phrenic circuitry.

Here, we describe a protocol for identifying phrenic motor neurons in mice after intrapleural delivery of fluorophore conjugated cholera toxin subunit beta. Two techniques are compared to inject the pleural cavity: transdiaphragmatic versus transthoracic approaches.

Retrograde neuroanatomischen Tracing der Phrenicus Motoneuronen bei Mäusen

Phrenic motor neurons are cervical motor neurons originating from C3 to C6 levels in most mammalian species. Axonal projections converge into phrenic ...

Targeting Alpha Synuclein Aggregates in Cutaneous Peripheral Nerve Fibers by Free-floating Immunofluorescence Assay

To date, for most neurodegenerative diseases only a post-mortem histopathological definitive diagnosis is available. For Parkinson&#39;s disease (PD), the diagnosis still relies only on clinical signs of motor involvement that appear later on in the disease course, when most of the dopaminergic neurons are already lost. Hence, there is a strong need for a biomarker that can identify patients at the beginning of disease or at the risk of developing it. Over the last few years, skin biopsy has proved to be an excellent research and diagnostic tool for peripheral nerve diseases such as small fiber neuropathy. Interestingly, a small fiber neuropathy and alpha synuclein (&#945;Syn) neural deposits have been shown by skin biopsy in PD patients. Indeed, skin biopsy has the great advantage of being an easily accessible, minimally invasive and painless procedure that allows the analysis of peripheral nervous tissue prone to the pathology. Moreover, the possibility of repeating the skin biopsy in the course of the follow-up of the same patient allows studying the longitudinal correlation with the disease progression. We set up a standardized reliable protocol to investigate the presence of &#945;Syn aggregates in skin nerve fibers of the PD patient. This protocol involves few short fixation steps, a cryotome sectioning and then a free-floating immunofluorescence double-staining with two specific antibodies: anti Protein Gene Product 9.5 (PGP9.5) to mark the cutaneous nerve fibers and anti 5G4 for detecting &#945;Syn aggregates. It is a versatile, sensitive and easy to perform protocol that can also be applied for targeting other proteins of interest in skin nerves. The ability to mark &#945;Syn aggregates is another step forward to the use of skin biopsy as a tool for establishing a pre-mortem histopathological diagnosis of PD.

Here, we present a protocol for a free-floating indirect immunofluorescence assay on skin biopsy sections that allows for the identification of disease specific conformation variants of alpha synuclein involved in Parkinson disease and multiple proteins of the peripheral nervous system.

Targeting Alpha Synuclein Aggregates in Kutane periphere Nervenfasern durch frei schwebenden Immunfluoreszenz-Assay

To date, for most neurodegenerative diseases only a post-mortem histopathological definitive diagnosis is available. For Parkinson&#39;s disease (PD), the ...