Les auteurs tiennent à remercier Neurotar Ltd pour l&#39;assistance technique, la Fondation de la CIMO et FGSN d&#39;un soutien financier.

Procédures portant sur des sujets animaux ont été approuvés par le Conseil d&#39;expérimentation animale nationale, de la Finlande. 1 Préparation des animaux pour l&#39;imagerie <ol><li> Anesthésier une souris par intraperitional (IP) injection de kétamine (0,08 mg par poids corporel) et de xylazine (0,01 mg par kg de poids corporel). Vérifiez l&#39;anesthésie avec l&#39;arrière réflexe orteil de pincement. </li><li> Plongez les yeux de l&#39;animal en collyre (Viscotears) pour protéger les yeux de la déshydratation. </li><li> Mettez la souris sur un coussin chauffant (Supertech) à 37 ° C pour éviter l&#39;hypothermie. </li><li> Nettoyer le coussinet plantaire désigné pour l&#39;imagerie avec 70% d&#39;éthanol. </li><li> Ajouter une goutte d&#39;eau sur la peau du coussinet plantaire pour le couplage d&#39;immersion entre la peau et le verre de couverture. </li><li> Placer un matériau d&#39;emballage en matière plastique sous la patte arrière qui est positionné sous une bague métallique de la classe de couverture. </li><li> Ajuster l&#39;épaisseur de la matière d&#39;emballage en plastique pour aplatir la peau. </li><li> Mettre une goutte d&#39;eau sur les glas de couvertures pour une immersion entre le verre et le couvercle de l&#39;objectif. </li></ol> 2. métal fixateur Anneau Préparation <ol><li> Pour la stabilisation de la peau utiliser le fixateur de métal. Nous utilisons de conception communautaire protégé fixateur deux ailes avec un anneau métallique (avec la permission de Neurotar Ltd, Finlande). Remplir la seringue avec de la colle, mettre la petite goutte de colle à travers l&#39;aiguille sur le ring et écartez doucement la colle pour une couverture uniforme de la surface de l&#39;anneau. Il est essentiel de mettre la quantité minimale de colle qui est nécessaire seulement pour une couverture uniforme, parce quantité excessive de colle peut réduire le champ de la vue et d&#39;entraver l&#39;imagerie ultérieure. NOTE: En variante, la combinaison d&#39;une barre de métal (par-dessous) et lame de verre de microscope standard (comme une couverture) peut être utilisé pour aplatir la peau et pour assurer un couplage optique correct de l&#39;ensemble 14. Deux trombones pourraient être utilisés pour fixer la patte entre le verre et la surface de la barre métallique (Figure 4 </strong&gt;). </li><li> Couvrir le ring avec lamelle de microscope (5 mm de diamètre, la microscopie électronique à la science). </li><li> Visser la bague fixateur à la barre de métal rigide qui est montaged sur la platine du microscope motorisé. </li></ol> 3. procédure d&#39;imagerie <ol><li> En cas d&#39;utilisation de la souris Thy1-YFP-H, choisissez la partie bleue de la lampe spectres de fluorescence pour visualiser les fibres nerveuses. Trouver le nerf d&#39;intérêt en mode épifluorescence et se concentrer sur elle. </li><li> Notez les coordonnées d&#39;un point pour l&#39;imagerie longitudinale. Utilisez un tampon carpien comme un point de référence. Pendant les séances d&#39;imagerie suivants, détecter d&#39;abord la plaquette carpien et ensuite trouver les mêmes fibres nerveuses de gros en amont et en revenir en utilisant les coordonnées enregistrées. Il est indispensable de positionner le coussinet de la patte dans la même direction perpendiculaire à la barre métallique afin de maintenir le même système de référence. </li><li> Activez le mode à deux photons. Pour les souris Thy1-YFP-H, il convient d&#39;utiliser la longueur d&#39;onde de 950 nm du rayonnement laserà visualiser les fibres nerveuses. </li><li> Sélectionner les longueurs d&#39;onde de laser et d&#39;émission des canaux (450 à 480 nm pour la seconde détection harmonique de production, de 520 à 550 nm pour l&#39;imagerie des nerfs YFP-marquées et de 580 à 630 nm pour la détection de la YFP fluorescence et l&#39;autofluorescence des cheveux), démarrer avec puissance laser faible (3-5%) pour prévenir le photovieillissement et de blanchiment. La tension typique sur les tubes photo-multiplicateurs est de 600 à 700 V pour ce type d&#39;imagerie. </li><li> Réglez la résolution souhaitée (512 x 512 ou 640 x 640 pour les événements des mesures rapides, 800 x 800 ou 1024 x 1024 pour l&#39;imagerie morphologique), étape axiale (1-3 pm), l&#39;épaisseur de l&#39;échantillon et les intervalles de temps (1-10 min). Le temps d&#39;exposition est de l&#39;ordre de 1 ms par un pixel. </li><li> Tout d&#39;abord marquer les limites supérieure et inférieure du volume d&#39;imagerie dans le logiciel. </li><li> Acquérir la pile d&#39;images de référence pour la référence avant la lésion. En cas de besoin, il est possible d&#39;enregistrer la ligne de base au cours de plusieurs minutes. </li><li&gt; À plusieurs reprises (au moins tous les 10-15 min) vérifier le taux et les réflexes de la respiration animale, en cas de besoin appliquer un montant supplémentaire d&#39;anesthésiques. </li><li> Après l&#39;imagerie propre le tampon avec un tissu et de mettre la souris dans une boîte de récupération à 36 ° C jusqu&#39;à ce qu&#39;il soit complètement réveillé. REMARQUE: En général, la durée d&#39;une session d&#39;imagerie combinée avec lésion induite par laser (voir ci-dessous) ne dépasse pas 1 heure. Nous vous recommandons de vérifier que l&#39;animal est profondément anesthésié toutes les 10-15 minutes; cela ne devrait pas interférer avec elle-même, mais l&#39;imagerie doit être considérée, alors que la procédure expérimentale est prévue. La durée de l&#39;effet d&#39;une dose unique de kétamine / de xylazyne est d&#39;environ 30 à 40 minutes, donc nous vous recommandons d&#39;appliquer davantage de ¼ à ½ dose après 25-30 min. REMARQUE: Il doit être considéré comme bien quand l&#39;expérimentation prévoit que la fréquence des séances d&#39;imagerie pour un animal ne doit pas dépasser 1 séance pour 2 jours pour éviter les effets négatifs de reanesthésie concurrentiel. </li></ol> 4. laser des lésions <ol><li> Après l&#39;acquisition de l&#39;image pile de référence, utiliser le protocole de blanchiment de faire une micro lésion. </li><li> Augmenter la puissance du laser de 100%. </li><li> Augmenter le temps d&#39;exposition à 100-1.000 ms par région d&#39;intérêt (100-1,000x plus que dans le cas de l&#39;imagerie standard). </li><li> Délimiter la zone de la lésion. </li><li> Faire la lésion par la mise en marche du blanchiment. </li><li> Revenez à la mode d&#39;imagerie régulier et continuer avec des enregistrements time-lapse. </li></ol> 5. traitement et analyse des données <ol><li> Procéder à unmixing utilisant Déconvolution spectrale plugin dans ImageJ 8 (Joachim Walter, <a href="http://rsbweb.nih.gov/ij/plugins/spectral-unmixing.html">http://rsbweb.nih.gov/ij/plugins/spectral-unmixing.html</a> ). </li><li> Ouvrez la pile d&#39;images et de diviser les canaux. </li><li> Trouvez la zone de libre des nerfs ou des cheveux pour les mesures de fond. Mettez une région ointérêt de f dans ce domaine. </li><li> Décrire avec soin la partie des cheveux où elle se distingue nettement des nerfs. </li><li> Exposer le nerf dans la partie de l&#39;image où elle est séparée de la chevelure. </li><li> Enregistrer unmixing matrice. </li><li> Appliquer matrice de unmixing mesurée pour l&#39;ensemble de la pile. </li><li> Enregistrez les nouveaux piles d&#39;images traitées au format * .tif. </li></ol>

<ol>
	<li>Lumpkin, E. A., Caterina, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+of+sensory+transduction+in+the+skin.">Mechanisms of sensory transduction in the skin.</a> Nature. 445, 858-865 (2007).</li><li>Kennedy, W. R., Wendelschafer-Crabb, G., Johnson, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitation+of+epidermal+nerves+in+diabetic+neuropathy.">Quantitation of epidermal nerves in diabetic neuropathy.</a> Neurology. 47, 1042-1048 (1996).</li><li>Wu, K. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morton's+interdigital+neuroma:+a+clinical+review+of+its+etiology,+treatment,+and+results.">Morton's interdigital neuroma: a clinical review of its etiology, treatment, and results.</a> J. Foot Ankle Surg. 35, 112-119 (1996).</li><li>Lauria, G., Lombardi, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Skin+biopsy:+a+new+tool+for+diagnosing+peripheral+neuropathy.">Skin biopsy: a new tool for diagnosing peripheral neuropathy.</a> BMJ. 334, 1159-1162 (2007).</li><li>Cheng, C., Guo, G. F., Martinez, J. A., Singh, V., Zochodne, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+plasticity+of+axons+within+a+cutaneous+milieu.">Dynamic plasticity of axons within a cutaneous milieu.</a> J. Neurosci. 30, 14735-14744 (2010).</li><li>Wang, B., Zinselmeyer, B. H., McDole, J. R., Gieselman, P. A., Miller, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-invasive+Imaging+of+Leukocyte+Homing+and+Migration+in+vivo.">Non-invasive Imaging of Leukocyte Homing and Migration in vivo.</a> J Vis Exp. (46), e2062 (2010).</li><li>Sacconi, L., O'Connor, R. P., Jasaitis, A., Masi, A., Buffelli, M., Pavone, F. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+multiphoton+nanosurgery+of+cortical+neurons.">In vivo multiphoton nanosurgery of cortical neurons.</a> J Biomed Opt. 12, 050502 (2007).</li><li>Robinson, L. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Traumatic+injury+to+peripheral+nerves.">Traumatic injury to peripheral nerves.</a> Muscle Nerve. 23, 863-873 (2000).</li><li>Feng, G., Mellor, R. H., Bernstein, M., Keller-Peck, C., Nguyen, Q. T., Wallace, M., Nerbonne, J. M., Lichtman, J. W., Sanes, J. R. <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+subsets+in+transgenic+mice+expressing+multiple+spectral+variants+of+GFP.">Imaging neuronal subsets in transgenic mice expressing multiple spectral variants of GFP.</a> Neuron. 28, 41-51 (2000).</li><li>Marinkovic, P., Reuter, M. S., Brill, M. 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H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lentiviral+gene+transfer+into+the+dorsal+root+ganglion+of+adult+rats.">Lentiviral gene transfer into the dorsal root ganglion of adult rats.</a> Mol Pain. 7, 63 (2011).</li><li>Yuryev, M., Khiroug, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+longitudinal+investigation+of+individual+nerve+endings+in+the+skin+of+anesthetized+mice+using+in+vivo+two-photon+microscopy.">Dynamic longitudinal investigation of individual nerve endings in the skin of anesthetized mice using in vivo two-photon microscopy.</a> J Biomed Opt. 17, 046007 (2012).</li></ol>

Les auteurs déclarent qu&#39;ils n&#39;ont aucun intérêt financier concurrents.

Dans ce protocole vidéo, nous démontrons le procédé de formation d&#39;image longitudinal à deux photons non-invasive de terminaisons nerveuses individuelles. La dynamique de l&#39;innervation de la peau est affectée dans des maladies telles que le psoriasis et la neuropathie périphérique 2, et dans les lésions traumatiques 9. L&#39;imagerie à deux photons permet une analyse détaillée des structures de fibres nerveuses dans la matrice de collagène. L&#39;ut...

A correction was made to <a href="/video/51045">In Vivo Two-Photon Microscopy of Single Nerve Endings in Skin</a>.
Leonard Khiroug was removed as an author.

Erratum: In Vivo Two-Photon Microscopy of Single Nerve Endings in Skin

Terminaisons nerveuses cutanées subissent des changements dynamiques sous différents états physiopathologiques. Les fibres nerveuses peuvent passer par le processus de dégénérescence et de régénération ou de restructuration dans le cadre de maladies telles que la neuropathie périphérique 2 ou Morton neurinome 3. Après un traumatisme, une partie importante de terminaisons nerveuses dynamique dans la peau est réinnervation de la zone endommagée. Cependant, l&#39;approche commune pour enquêter sur les terminaisons nerveuses est ex vivo histologique sectionnement qui manque d&#39;informations en temps réel sur les processus en cours 4. En utilisant des marqueurs fluorescents génétiquement codés, il est possible de suivre les terminaisons nerveuses de la peau d&#39;animaux vivants, obtenant ainsi une information riche et beaucoup plus pertinentes sur les changements structurels. L&#39;étude des terminaisons nerveuses cutanées est possible en utilisant la microscopie à fluorescence classique, cependant, la forte dispersion de la lumière du tissu cutané compromet fortement la qualitédes données acquises 5. La microscopie multiphotonique permet l&#39;acquisition d&#39;images à haute résolution dans les tissus fortement de diffusion en raison de la somme non-linéaire de l&#39;énergie des photons de lumière d&#39;excitation résultant des émissions de fluorescence seulement du point focal de l&#39;objectif. Cet effet conduit à une forte augmentation de la profondeur de pénétration et une amélioration de rapport signal sur bruit de la mesure, dans les tissus de la peau 6. En utilisant le même laser pour l&#39;imagerie, il est possible de produire dissection sélective des fibres nerveuses 7. Dans le protocole suivant, nous montrons le procédé d&#39;imagerie longitudinal de terminaisons nerveuses cutanées in vivo dans des souris transgéniques reporter associé à une lésion sélective au laser disponible dans le commerce en utilisant le système de microscope multiphotonique.

<table border="0" cellpadding="0" cellspacing="0" width="1231">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Round cover glass&#160;</td>
			<td style="width:209px;">Electron Microscopy Science</td>
			<td style="width:119px;">72296-05</td>
			<td style="width:687px;">5 mm diameter #1.5 thickness</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Eye drops Viscotears</td>
			<td style="width:209px;">Novartis</td>
			<td style="width:119px;"></td>
			<td>2mg/g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Superglue Loctite 401</td>
			<td style="width:209px;">Henkel</td>
			<td>135429</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Ketaminol</td>
			<td style="width:209px;">Intervet</td>
			<td style="width:119px;"></td>
			<td>Ketamine 50 mg/ml, working solution 10 mg/ml (use it 80 &#181;g per gramm of animal weight)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Rompun</td>
			<td style="width:209px;">Bayer Healthcare</td>
			<td style="width:119px;"></td>
			<td>Xylazine 20 mg/ml, working solution 1.25 mg/ml (use it 10 &#181;g per gramm of animal weight)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;"></td>
			<td style="width:209px;"></td>
			<td style="width:119px;"></td>
			<td style="width:687px;">Working solution is a mixture of Ketamine 10 mg/ml and Xylazine 1.25 mg/ml in PBS</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Ethanol 70%</td>
			<td style="width:209px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Distilled water or Milli-Q water</td>
			<td style="width:209px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Syringes 1ml&#160;</td>
			<td style="width:209px;">BD</td>
			<td style="width:119px;">300013</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">30G 1/2&#34; needles</td>
			<td style="width:209px;">BD</td>
			<td style="width:119px;">304000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Plastic packaging material</td>
			<td style="width:209px;"></td>
			<td style="width:119px;"></td>
			<td>Could be purchaized from general hardware store</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">FV-1000MPE microscope</td>
			<td style="width:209px;">Olympus</td>
			<td style="width:119px;">FV-1000MPE</td>
			<td>Microscope with motorized stage and rigid metal bar for fixation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">25X XLPlan objective</td>
			<td style="width:209px;">Olympus</td>
			<td style="width:119px;">XLPLN 25XWMP</td>
			<td>Water imersion objective optimized for multiphoton imaging</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Mai-Tai DeepSee laser (2W)</td>
			<td style="width:209px;">SpectraPhysics</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Heating pad</td>
			<td style="width:209px;">Supertech</td>
			<td style="width:119px;">TMP-5b</td>
			<td>Heating pad with a temperature controller</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Metal ring fixator</td>
			<td style="width:209px;">Neurotar Ltd.</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ImageJ</td>
			<td style="width:209px;">NIH</td>
			<td style="width:119px;"></td>
			<td>Open source software for image processing and analysis, http://rsbweb.nih.gov/ij/&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Thy1-YFPH mice strain</td>
			<td style="width:209px;">JaxLab</td>
			<td style="width:119px;">003782</td>
			<td></td>
		</tr>
	</tbody>
</table>

in vivo two-photon microscopy of single nerve endings in skin

Les terminaisons nerveuses de la peau sont impliqués dans des processus physiologiques tels que la détection d&#39;une aussi dans des processus pathologiques tels que la douleur neuropathique 2. Leur positionnement proche de la surface facilite l&#39;imagerie microscopique de terminaisons nerveuses de la peau chez l&#39;animal intact vivant. En utilisant la microscopie multiphotonique, il est possible d&#39;obtenir des images fines à surmonter le problème de la forte dispersion de la lumière du tissu cutané. Reporter souris transgéniques qui expriment EYFP sous le contrôle de Thy-1 promoteur dans les neurones (y compris la périphérie des neurones sensoriels) sont bien adaptés pour les études longitudinales de chaque terminaisons nerveuses sur des périodes de temps prolongées jusqu&#39;à plusieurs mois, voire toute une vie. En outre, en utilisant le même laser femtoseconde comme pour l&#39;imagerie, il est possible de produire des lésions hautement sélectifs des fibres nerveuses pour les études de la restructuration de fibres nerveuses. Ici, nous présentons un protocole simple et fiable pour multiphotonique longitudinale en imagerie in vivo etmicrochirurgie au laser sur la souris terminaisons nerveuses de la peau.

Selon la méthode décrite, il est possible de suivre la même fibre après la lésion et à l&#39;étude de la dégradation des terminaisons nerveuses endommagées (figure 1). Acquisition de la pile à l&#39;épaisseur de 120 à 150 um est généralement approprié pour l&#39;imagerie répétitive pendant plusieurs jours afin de maintenir l&#39;ensemble de fibres dans le champ de vision. La lésion peut généralement être réalisée de façon concise lorsque le matériau ...

Watch this Scientific Journal Video about In Vivo Two-Photon Microscopy of Single Nerve Endings in Skin at JoVE.com

In Vivo Two-Photon Microscopy of Single Nerve Endings in Skin

Le protocole pour l&#39;imagerie dynamique longitudinale et lésion laser sélectif de terminaisons nerveuses chez des souris transgéniques reporter est présente.

In Vivo microscopie à deux photons de terminaisons nerveuses dans la peau simples

Nerve endings in skin are involved in physiological processes such as sensing1 as well as in pathological processes such as neuropathic pain2. Their ...

in-vivo-two-photon-microscopy-of-single-nerve-endings-in-skin

Research

JoVE Journal

Neuroscience

In Vivo Two-Photon Microscopy of Single Nerve Endings in Skin

10.7K vues.  University of Helsinki.  Le protocole pour l'imagerie dynamique longitudinale et lésion laser sélectif de terminaisons nerveuses chez des souris transgéniques reporter est présente. 

Vidéo: In Vivo Two-Photon Microscopy of Single Nerve Endings in Skin

In vivo Imaging of the Mouse Spinal Cord Using Two-photon Microscopy

In vivo imaging using two-photon microscopy 1 in mice that have been genetically engineered to express fluorescent proteins in specific cell types 2-3 has significantly broadened our knowledge of physiological and pathological processes in numerous tissues in vivo 4-7. In studies of the central nervous system (CNS), there has been a broad application of in vivo imaging in the brain, which has produced a plethora of novel and often unexpected findings about the behavior of cells such as neurons, astrocytes, microglia, under physiological or pathological conditions 8-17. However, mostly technical complications have limited the implementation of in vivo imaging in studies of the living mouse spinal cord. In particular, the anatomical proximity of the spinal cord to the lungs and heart generates significant movement artifact that makes imaging the living spinal cord a challenging task.
We developed a novel method that overcomes the inherent limitations of spinal cord imaging by stabilizing the spinal column, reducing respiratory-induced movements and thereby facilitating the use of two-photon microscopy to image the mouse spinal cord in vivo. This is achieved by combining a customized spinal stabilization device with a method of deep anesthesia, resulting in a significant reduction of respiratory-induced movements. This video protocol shows how to expose a small area of the living spinal cord that can be maintained under stable physiological conditions over extended periods of time by keeping tissue injury and bleeding to a minimum. Representative raw images acquired in vivo detail in high resolution the close relationship between microglia and the vasculature. A timelapse sequence shows the dynamic behavior of microglial processes in the living mouse spinal cord. Moreover, a continuous scan of the same z-frame demonstrates the outstanding stability that this method can achieve to generate stacks of images and/or timelapse movies that do not require image alignment post-acquisition. Finally, we show how this method can be used to revisit and reimage the same area of the spinal cord at later timepoints, allowing for longitudinal studies of ongoing physiological or pathological processes in vivo.

In vivo Imaging of the Mouse Spinal Cord Using Two-photon Microscopy

A minimally invasive protocol to stabilize the mouse spinal column and perform repetitive in vivo spinal cord imaging using two-photon microscopy is described. This method combines a spinal stabilization device and an anesthetic regimen to minimize respiratory-induced movements and produce raw imaging data that require no alignment or other post-processing.

Dans l&#39;imagerie in vivo de la moelle épinière de souris utilisant microscopie à deux photons

In vivo imaging using two-photon microscopy 1 in mice that have been genetically engineered to express fluorescent proteins in specific cell types 2-3 has ...

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Neurosciences

Retrograde Fluorescent Labeling Allows for Targeted Extracellular Single-unit Recording from Identified Neurons In vivo

The overall goal of this method is to record single-unit responses from an identified population of neurons. In vivo electrophysiological recordings from individual neurons are critical for understanding how neural circuits function under natural conditions. Traditionally, these recordings have been performed 'blind', meaning the identity of the recorded cell is unknown at the start of the recording. Cellular identity can be subsequently determined via intracellular1, juxtacellular2 or loose-patch3 iontophoresis of dye, but these recordings cannot be pre-targeted to specific neurons in regions with functionally heterogeneous cell types. Fluorescent proteins can be expressed in a cell-type specific manner permitting visually-guided single-cell electrophysiology4-6. However, there are many model systems for which these genetic tools are not available. Even in genetically accessible model systems, the desired promoter may be unknown or genetically homogenous neurons may have varying projection patterns. Similarly, viral vectors have been used to label specific subgroups of projection neurons7, but use of this method is limited by toxicity and lack of trans-synaptic specificity. Thus, additional techniques that offer specific pre-visualization to record from identified single neurons in vivo are needed. Pre-visualization of the target neuron is particularly useful for challenging recording conditions, for which classical single-cell recordings are often prohibitively difficult8-11. The novel technique described in this paper uses retrograde transport of a fluorescent dye applied using tungsten needles to rapidly and selectively label a specific subset of cells within a particular brain region based on their unique axonal projections, thereby providing a visual cue to obtain targeted electrophysiological recordings from identified neurons in an intact circuit within a vertebrate CNS.
The most significant novel advancement of our method is the use of fluorescent labeling to target specific cell types in a non-genetically accessible model system. Weakly electric fish are an excellent model system for studying neural circuits in awake, behaving animals12. We utilized this technique to study sensory processing by "small cells" in the anterior exterolateral nucleus (ELa) of weakly electric mormyrid fish. "Small cells" are hypothesized to be time comparator neurons important for detecting submillisecond differences in the arrival times of presynaptic spikes13. However, anatomical features such as dense myelin, engulfing synapses, and small cell bodies have made it extremely difficult to record from these cells using traditional methods11, 14. Here we demonstrate that our novel method selectively labels these cells in 28% of preparations, allowing for reliable, robust recordings and characterization of responses to electrosensory stimulation.

Retrograde Fluorescent Labeling Allows for Targeted Extracellular Single-unit Recording from Identified Neurons In vivo

Retrograde transport of fluorescent dye labels a sub-population of neurons based on anatomical projection. Labeled axons can be visually targeted in vivo, permitting extracellular recording from identified axons. This technique facilitates recording when neurons cannot be labeled through genetic manipulation or are difficult to isolate using 'blind' in vivo approaches.

Marquage fluorescent rétrograde Permet ciblée extracellulaire seule unité d&#39;enregistrement de neurones identifiés<em&gt; In vivo</em

The overall goal of this method is to record single-unit responses from an identified population of neurons. In vivo electrophysiological recordings from ...

Functional Neuroimaging Using Ultrasonic Blood-brain Barrier Disruption and Manganese-enhanced MRI

Although mice are the dominant model system for studying the genetic and molecular underpinnings of neuroscience, functional neuroimaging in mice remains technically challenging. One approach, Activation-Induced Manganese-enhanced MRI (AIM MRI), has been used successfully to map neuronal activity in rodents 1-5. In AIM MRI, Mn2+ acts a calcium analog and accumulates in depolarized neurons 6,7. Because Mn2+ shortens the T1 tissue property, regions of elevated neuronal activity will enhance in MRI. Furthermore, Mn2+ clears slowly from the activated regions; therefore, stimulation can be performed outside the magnet prior to imaging, enabling greater experimental flexibility. However, because Mn2+ does not readily cross the blood-brain barrier (BBB), the need to open the BBB has limited the use of AIM MRI, especially in mice.
One tool for opening the BBB is ultrasound. Though potentially damaging, if ultrasound is administered in combination with gas-filled microbubbles (i.e., ultrasound contrast agents), the acoustic pressure required for BBB opening is considerably lower. This combination of ultrasound and microbubbles can be used to reliably open the BBB without causing tissue damage 8-11.
Here, a method is presented for performing AIM MRI by using microbubbles and ultrasound to open the BBB. After an intravenous injection of perflutren microbubbles, an unfocused pulsed ultrasound beam is applied to the shaved mouse head for 3 minutes. For simplicity, we refer to this technique of BBB Opening with Microbubbles and UltraSound as BOMUS 12. Using BOMUS to open the BBB throughout both cerebral hemispheres, manganese is administered to the whole mouse brain. After experimental stimulation of the lightly sedated mice, AIM MRI is used to map the neuronal response.
To demonstrate this approach, herein BOMUS and AIM MRI are used to map unilateral mechanical stimulation of the vibrissae in lightly sedated mice 13. Because BOMUS can open the BBB throughout both hemispheres, the unstimulated side of the brain is used to control for nonspecific background stimulation. The resultant 3D activation map agrees well with published representations of the vibrissae regions of the barrel field cortex 14. The ultrasonic opening of the BBB is fast, noninvasive, and reversible; and thus this approach is suitable for high-throughput and/or longitudinal studies in awake mice.

A technique is described for broadly opening the blood-brain barrier in the mouse using microbubbles and ultrasound. Using this technique, manganese can be administered to the mouse brain. Because manganese is an MRI contrast agent that accumulates in depolarized neurons, this approach enables imaging of neuronal activity.

Utilisation de neuro-imagerie fonctionnelle par ultrasons rupture de la barrière hémato-encéphalique et le manganèse-IRM

Although mice are the dominant model system for studying the genetic and molecular underpinnings of neuroscience, functional neuroimaging in mice remains ...

In Vivo Two-photon Imaging Of Experience-dependent Molecular Changes In Cortical Neurons

The brain's ability to change in response to experience is essential for healthy brain function, and abnormalities in this process contribute to a variety of brain disorders1,2. To better understand the mechanisms by which brain circuits react to an animal's experience requires the ability to monitor the experience-dependent molecular changes in a given set of neurons, over a prolonged period of time, in the live animal. While experience and associated neural activity is known to trigger gene expression changes in neurons1,2, most of the methods to detect such changes do not allow repeated observation of the same neurons over multiple days or do not have sufficient resolution to observe individual neurons3,4. Here, we describe a method that combines in vivo two-photon microscopy with a genetically encoded fluorescent reporter to track experience-dependent gene expression changes in individual cortical neurons over the course of day-to-day experience. 
One of the well-established experience-dependent genes is Activity-regulated cytoskeletal associated protein (Arc)5,6. The transcription of Arc is rapidly and highly induced by intensified neuronal activity3, and its protein product regulates the endocytosis of glutamate receptors and long-term synaptic plasticity7. The expression of Arc has been widely used as a molecular marker to map neuronal circuits involved in specific behaviors3. In most of those studies, Arc expression was detected by in situ hybridization or immunohistochemistry in fixed brain sections. Although those methods revealed that the expression of Arc was localized to a subset of excitatory neurons after behavioral experience, how the cellular patterns of Arc expression might change with multiple episodes of repeated or distinctive experiences over days was not investigated. 
In vivo two-photon microscopy offers a powerful way to examine experience-dependent cellular changes in the living brain8,9. To enable the examination of Arc expression in live neurons by two-photon microscopy, we previously generated a knock-in mouse line in which a GFP reporter is placed under the control of the endogenous Arc promoter10. This protocol describes the surgical preparations and imaging procedures for tracking experience-dependent Arc-GFP expression patterns in neuronal ensembles in the live animal. In this method, chronic cranial windows were first implanted in Arc-GFP mice over the cortical regions of interest. Those animals were then repeatedly imaged by two-photon microscopy after desired behavioral paradigms over the course of several days. This method may be generally applicable to animals carrying other fluorescent reporters of experience-dependent molecular changes4.

In Vivo Two-photon Imaging Of Experience-dependent Molecular Changes In Cortical Neurons

Experience-dependent molecular changes in neurons are essential for the brain's ability to adapt in response to behavioral challenges. An in vivo two-photon imaging method is described here that allows the tracking of such molecular changes in individual cortical neurons through genetically encoded reporters.

In Vivo Imagerie biphotonique d&#39;expérience qui dépendent des changements moléculaires dans les neurones corticaux

The brain's ability to change in response to experience is essential for healthy brain function, and abnormalities in this process contribute to a variety ...

Two-Photon in vivo Imaging of Dendritic Spines in the Mouse Cortex Using a Thinned-skull Preparation

In the mammalian cortex, neurons form extremely complicated networks and exchange information at synapses. Changes in synaptic strength, as well as addition/removal of synapses, occur in an experience-dependent manner, providing the structural foundation of neuronal plasticity. As postsynaptic components of the most excitatory synapses in the cortex, dendritic spines are considered to be a good proxy of synapses. Taking advantages of mouse genetics and fluorescent labeling techniques, individual neurons and their synaptic structures can be labeled in the intact brain. Here we introduce a transcranial imaging protocol using two-photon laser scanning microscopy to follow fluorescently labeled postsynaptic dendritic spines over time in vivo. This protocol utilizes a thinned-skull preparation, which keeps the skull intact and avoids inflammatory effects caused by exposure of the meninges and the cortex. Therefore, images can be acquired immediately after surgery is performed. The experimental procedure can be performed repetitively over various time intervals ranging from hours to years. The application of this preparation can also be expanded to investigate different cortical regions and layers, as well as other cell types, under physiological and pathological conditions.

Two-Photon in vivo Imaging of Dendritic Spines in the Mouse Cortex Using a Thinned-skull Preparation

Time-lapse imaging in the living animal provides valuable information on structural reorganization in the intact brain. Here, we introduce a thinned-skull preparation that allows transcranial imaging of fluorescently labeled synaptic structures in the living mouse cortex by two-photon microscopy.

Deux-Photon<em&gt; In vivo</em&gt; Imagerie des épines dendritiques dans le cortex de souris utilisant un crâne-Diluée Préparation

In the mammalian cortex, neurons form extremely complicated networks and exchange information at synapses. Changes in synaptic strength, as well as ...

Simultaneous Two-photon In Vivo Imaging of Synaptic Inputs and Postsynaptic Targets in the Mouse Retrosplenial Cortex

This video shows the craniotomy procedure that allows chronic imaging of neurons in the mouse retrosplenial cortex (RSC) using in vivo two-photon microscopy in Thy1-GFP transgenic mouse line. This approach creates a possibility to investigate the correlation of behavioural manipulations with changes in neuronal morphology in vivo.
The cranial window implantation procedure was considered to be limited only to the easily accessible cortex regions such as the barrel field. Our approach allows visualization of neurons in the highly vascularized RSC. RSC is an important element of the brain circuit responsible for spatial memory, previously deemed to be problematic for in vivo two-photon imaging.
The cranial window implantation over the RSC is combined with an injection of mCherry-expressing recombinant adeno-associated virus (rAAVmCherry) into the dorsal hippocampus. The expressed mCherry spreads out to axonal projections from the hippocampus to RSC, enabling the visualization of changes in both presynaptic axonal boutons and postsynaptic dendritic spines in the cortex. 
This technique allows long-term monitoring of experience-dependent structural plasticity in RSC.

Simultaneous Two-photon In Vivo Imaging of Synaptic Inputs and Postsynaptic Targets in the Mouse Retrosplenial Cortex

This video shows the craniotomy procedure that allows chronic imaging of neurons in mouse retrosplenial cortex using in vivo two photon microscopy in Thy1-GFP transgenic line. This approach is combined with injection of mCherry-expressing adeno-associated virus into dorsal hippocampus. These techniques allow long-term monitoring of experience-dependent structural plasticity in RSC.

Simultanée à deux photons<em&gt; In Vivo</em&gt; Imagerie d&#39;entrées synaptiques et les cibles postsynaptiques dans le Cortex Souris rétrosplénial

This video shows the craniotomy procedure that allows chronic imaging of neurons in the mouse retrosplenial cortex (RSC) using in vivo two-photon ...

Quantification of Cerebral Vascular Architecture using Two-photon Microscopy in a Mouse Model of HIV-induced Neuroinflammation

Human Immunodeficiency Virus 1 (HIV-1) infection frequently results in HIV-1 Associated Neurocognitive Disorders (HAND), and is characterized by a chronic neuroinflammatory state within the central nervous system (CNS), thought to be driven principally by virally-mediated activation of microglia and brain resident macrophages. HIV-1 infection is also accompanied by changes in cerebrovascular blood flow (CBF), raising the possibility that HIV-associated chronic neuroinflammation may lead to changes in CBF and/or in cerebral vascular architecture. To address this question, we have used a mouse model for HIV-induced neuroinflammation, and we have tested whether long-term exposure to this inflammatory environment may damage brain vasculature and result in rarefaction of capillary networks. In this paper we describe a method to quantify changes in cortical capillary density in a mouse model of neuroinflammatory disease (HIV-1 Tat transgenic mice). This generalizable approach employs in vivo two-photon imaging of cortical capillaries through a thin-skull cortical window, as well as ex vivo two-photon imaging of cortical capillaries in mouse brain sections. These procedures produce images and z-stack files of capillary networks, respectively, which can be then subjected to quantitative analysis in order to assess changes in cerebral vascular architecture.

This paper describes a method by which the vascular architecture in the brain can be quantified using in vivo and ex vivo two-photon microscopy.

Quantification de l&#39;architecture vasculaire cérébral en utilisant la microscopie à deux photons dans un modèle de souris de la neuro-inflammation induite par le VIH

Human Immunodeficiency Virus 1 (HIV-1) infection frequently results in HIV-1 Associated Neurocognitive Disorders (HAND), and is characterized by a chronic ...

Optical Monitoring of Living Nerve Terminal Labeling in Hair Follicle Lanceolate Endings of the Ex Vivo Mouse Ear Skin

A novel dissection and recording technique is described for optical monitoring staining and de-staining of lanceolate terminals surrounding hair follicles in the skin of the mouse pinna. The preparation is simple and relatively fast, reliably yielding extensive regions of multiple labeled units of living nerve terminals to study uptake and release of styryl pyridinium dyes extensively used in studies of vesicle recycling. Subdividing the preparations before labeling allows test vs. control comparisons in the same ear from a single individual. Helpful tips are given for improving the quality of the preparation, the labeling and the imaging parameters. This new system is suitable for assaying pharmacologically and mechanically-induced uptake and release of these vital dyes in lanceolate terminals in both wild-type and genetically modified animals. Examples of modulatory influences on labeling intensity are given.

Optical Monitoring of Living Nerve Terminal Labeling in Hair Follicle Lanceolate Endings of the Ex Vivo Mouse Ear Skin

Here we describe a novel preparation for imaging live lanceolate sensory terminals of palisade endings that innervate mouse ear skin hair follicles during staining and destaining with styryl pyridinium dyes.

Surveillance optique de Living Nerve Terminal Marquer follicule pileux lancéolées Endings du<em&gt; Ex Vivo</em&gt; Souris oreille peau

A novel dissection and recording technique is described for optical monitoring staining and de-staining of lanceolate terminals surrounding hair follicles ...

Two-photon Calcium Imaging in Neuronal Dendrites in Brain Slices

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

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

Imagerie biphotonique Calcium en Dendrites neuronales dans des tranches de cerveau

Calcium (Ca2+) imaging is a powerful tool to investigate the spatiotemporal dynamics of intracellular Ca2+ signals in neuronal dendrites. Ca2+ ...

In Vivo Two-photon Imaging of Cortical Neurons in Neonatal Mice

Two-photon imaging is a powerful tool for the in vivo analysis of neuronal circuits in the mammalian brain. However, a limited number of in vivo imaging methods exist for examining the brain tissue of live newborn mammals. Herein we summarize a protocol for imaging individual cortical neurons in living neonatal mice. This protocol includes the following two methodologies: (1) the Supernova system for sparse and bright labeling of cortical neurons in the developing brain, and (2) a surgical procedure for the fragile neonatal skull. This protocol allows the observation of temporal changes of individual cortical neurites during neonatal stages with a high signal-to-noise ratio. Labeled cell-specific gene silencing and knockout can also be achieved by combining the Supernova with RNA interference and CRISPR/Cas9 gene editing systems. This protocol can, thus, be used for analyzing the developmental dynamics of cortical neurons, molecular mechanisms that control the neuronal dynamics, and changes in neuronal dynamics in disease models.

In Vivo Two-photon Imaging of Cortical Neurons in Neonatal Mice

We present an in vivo two-photon imaging protocol for imaging the cerebral cortex of neonatal mice. This method is suitable for analyzing the developmental dynamics of cortical neurons, the molecular mechanisms that control the neuronal dynamics, and the changes in neuronal dynamics in disease models.

In Vivo Two-photon Imaging de neurones corticaux en souris néonatales

Two-photon imaging is a powerful tool for the in vivo analysis of neuronal circuits in the mammalian brain. However, a limited number of in vivo imaging ...