Name: using baseplating and a miniscope preanchored with an objective lens for calcium transient research in mice
Uploaded: 2021-06-05T15:00:00
Description: Watch this Scientific Journal Video about Using Baseplating and a Miniscope Preanchored with an Objective Lens for Calcium Transient Research in Mice at JoVE.com

This work was supported by the Ministry of Science and Technology, Taiwan (108-2320-B-002 -074, 109-2320-B-002-023-MY2).

All procedures performed in this study were approved by the National Taiwan University Animal Care and Use Committee (Approval No.: NTU-109-EL-00029 and NTU-108-EL-00158).
1. Assessment of the volume alteration of dental cement
NOTE: Changes in the volume of dental cement occur during the curing process. Test the volume changes of dental cement before implantation and baseplating. Researchers can test any brand of dental cement an...

<ol>
	<li>Tian, L., Hires, S. A., Looger, L. L. <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+activity+with+genetically+encoded+calcium+indicators.">Imaging neuronal activity with genetically encoded calcium indicators.</a> Cold Spring Harbor Protocols. 2012 (6), 647-656 (2012).</li><li>Grienberger, C., Konnerth, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+calcium+in+neurons.">Imaging calcium in neurons.</a> Neuron. 73 (5), 862-885 (2012).</li><li>Dana, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-performance+calcium+sensors+for+imaging+activity+in+neuronal+populations+and+microcompartments.">High-performance calcium sensors for imaging activity in neuronal populations and microcompartments.</a> Nature Methods. 16 (7), 649-657 (2019).</li><li>Campos, P., Walker, J. J., Mollard, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diving+into+the+brain:+deep-brain+imaging+techniques+in+conscious+animals.">Diving into the brain: deep-brain imaging techniques in conscious animals.</a> Journal of Endocrinology. 246 (2), 33-50 (2020).</li><li>Ghosh, K. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Miniaturized+integration+of+a+fluorescence+microscope.">Miniaturized integration of a fluorescence microscope.</a> Nature Methods. 8 (10), 871-878 (2011).</li><li>de Groot, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NINscope,+a+versatile+miniscope+for+multi-region+circuit+investigations.">NINscope, a versatile miniscope for multi-region circuit investigations.</a> Elife. 9, 49987 (2020).</li><li>Aharoni, D., Hoogland, T. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Circuit+investigations+with+open-source+miniaturized+microscopes:+past,+present+and+future.">Circuit investigations with open-source miniaturized microscopes: past, present and future.</a> Frontiers in Cellular Neuroscience. 13, 141 (2019).</li><li>Resendez, S. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualization+of+cortical,+subcortical+and+deep+brain+neural+circuit+dynamics+during+naturalistic+mammalian+behavior+with+head-mounted+microscopes+and+chronically+implanted+lenses.">Visualization of cortical, subcortical and deep brain neural circuit dynamics during naturalistic mammalian behavior with head-mounted microscopes and chronically implanted lenses.</a> Nature Protocols. 11 (3), 566-597 (2016).</li><li>Aharoni, D., Khakh, B. S., Silva, A. J., Golshani, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=All+the+light+that+we+can+see:+a+new+era+in+miniaturized+microscopy.">All the light that we can see: a new era in miniaturized microscopy.</a> Nature Methods. 16 (1), 11-13 (2019).</li><li>Lee, H. S., Han, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Successful+in+vivo+calcium+imaging+with+a+head-mount+miniaturized+microscope+in+the+amygdala+of+freely+behaving+mouse.">Successful in vivo calcium imaging with a head-mount miniaturized microscope in the amygdala of freely behaving mouse.</a> Journal of Visualized Experiments. (162), e61659 (2020).</li><li>Cai, D. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+shared+neural+ensemble+links+distinct+contextual+memories+encoded+close+in+time.">A shared neural ensemble links distinct contextual memories encoded close in time.</a> Nature. 534 (7605), 115-118 (2016).</li><li>Chen, K. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+hypothalamic+switch+for+REM+and+Non-REM+sleep.">A hypothalamic switch for REM and Non-REM sleep.</a> Neuron. 97 (5), 1168-1176 (2018).</li><li>Shuman, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Breakdown+of+spatial+coding+and+interneuron+synchronization+in+epileptic+mice.">Breakdown of spatial coding and interneuron synchronization in epileptic mice.</a> Nature Neuroscience. 23 (2), 229-238 (2020).</li><li>Jimenez, J. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anxiety+cells+in+a+hippocampal-hypothalamic+circuit.">Anxiety cells in a hippocampal-hypothalamic circuit.</a> Neuron. 97 (3), 670-683 (2018).</li><li>Hart, E. E., Blair, G. J., O'Dell, T. J., Blair, H. T., Izquierdo, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemogenetic+modulation+and+single-photon+calcium+imaging+in+anterior+cingulate+cortex+reveal+a+mechanism+for+effort-based+decisions.">Chemogenetic modulation and single-photon calcium imaging in anterior cingulate cortex reveal a mechanism for effort-based decisions.</a> Journal of Neuroscience. , 2548 (2020).</li><li>Gulati, S., Cao, V. Y., Otte, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multi-layer+cortical+Ca2++imaging+in+freely+moving+mice+with+prism+probes+and+miniaturized+fluorescence+microscopy.">Multi-layer cortical Ca2+ imaging in freely moving mice with prism probes and miniaturized fluorescence microscopy.</a> Journal of Visualized Experiments. (124), e55579 (2017).</li><li>Zhang, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Miniscope+GRIN+lens+system+for+calcium+imaging+of+neuronal+activity+from+deep+brain+structures+in+behaving+animals.">Miniscope GRIN lens system for calcium imaging of neuronal activity from deep brain structures in behaving animals.</a> Current Protocols in Neuroscience. 86 (1), 56 (2019).</li><li>Corder, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+amygdalar+neural+ensemble+that+encodes+the+unpleasantness+of+pain.">An amygdalar neural ensemble that encodes the unpleasantness of pain.</a> Science. 363 (6424), 276-281 (2019).</li><li>Liberti, W. A., Perkins, L. N., Leman, D. P., Gardner, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+open+source,+wireless+capable+miniature+microscope+system.">An open source, wireless capable miniature microscope system.</a> Journal of Neural Engineering. 14 (4), 045001 (2017).</li><li>Lu, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MIN1PIPE:+A+miniscope+1-photon-based+calcium+imaging+signal+extraction+pipeline.">MIN1PIPE: A miniscope 1-photon-based calcium imaging signal extraction pipeline.</a> Cell Reports. 23 (12), 3673-3684 (2018).</li><li>Giovannucci, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CaImAn+an+open+source+tool+for+scalable+calcium+imaging+data+analysis.">CaImAn an open source tool for scalable calcium imaging data analysis.</a> Elife. 8, 38173 (2019).</li><li>Lee, A. K., Manns, I. D., Sakmann, B., Brecht, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Whole-cell+recordings+in+freely+moving+rats.">Whole-cell recordings in freely moving rats.</a> Neuron. 51 (4), 399-407 (2006).</li><li>Burger, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recombinant+AAV+viral+vectors+pseudotyped+with+viral+capsids+from+serotypes+1,+2,+and+5+display+differential+efficiency+and+cell+tropism+after+delivery+to+different+regions+of+the+central+nervous+system.">Recombinant AAV viral vectors pseudotyped with viral capsids from serotypes 1, 2, and 5 display differential efficiency and cell tropism after delivery to different regions of the central nervous system.</a> Molecular Therapy. 10 (2), 302-317 (2004).</li><li>Royo, N. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Specific+AAV+serotypes+stably+transduce+primary+hippocampal+and+cortical+cultures+with+high+efficiency+and+low+toxicity.">Specific AAV serotypes stably transduce primary hippocampal and cortical cultures with high efficiency and low toxicity.</a> Brain Research. 1190, 15-22 (2008).</li><li>Gage, G. J., Kipke, D. R., Shain, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Whole+animal+perfusion+fixation+for+rodents.">Whole animal perfusion fixation for rodents.</a> Journal of Visualized Experiments. (65), e3564 (2012).</li><li>Ziv, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Long-term+dynamics+of+CA1+hippocampal+place+codes.">Long-term dynamics of CA1 hippocampal place codes.</a> Nature Neuroscience. 16 (3), 264-266 (2013).</li><li>Gargiulo, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mice+anesthesia,+analgesia,+and+care,+Part+I:+anesthetic+considerations+in+preclinical+research.">Mice anesthesia, analgesia, and care, Part I: anesthetic considerations in preclinical research.</a> ILAR journal / National Research Council, Institute of Laboratory Animal Resources. 53 (1), 55-69 (2012).</li></ol>

The present report describes a detailed experimental protocol for researchers using the two-lens UCLA Miniscope system. The tools designed in our protocol are relatively affordable for any laboratory that wishes to try in vivo calcium imaging. Some protocols, such as viral injection, lens implantation, dummy baseplating, and baseplating, could also be used for other versions of the miniscope system to improve the success rate of calcium imaging. Other than general problems with viral injection, and lens implanta...

Fluorescent activity reporters are ideal for imaging of the neuronal activity because they are sensitive and have large dynamic ranges1,2,3. Therefore, an increasing number of experiments are using fluorescence microscopy to directly observe neuronal activity1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16. The first miniaturized one-photon fluorescence microscope (miniscope) was designed in 2011 by Mark Schnitzer et al.5. This miniscope enables researchers to monitor the fluorescence dynamics of cerebellar cells in freely behaving animals5 (i.e., without any physical restraint, head restraint, sedation, or anesthesia to the animals). Currently, the technique can be applied to monitor superficial brain areas such as the cortex6,8,15,16; subcortical areas such as the dorsal hippocampus8,11,13,14 and striatum6,17; and deep brain areas such as the ventral hippocampus14, amygdala10,18, and hypothalamus8,12.
In recent years, several open-source miniscopes have been developed4,5,6,7,11,13,17,19. The miniscope can be economically assembled by researchers if they follow the step-by-step guidelines provided by the University of California, Los Angeles (UCLA) Miniscope team4,7,11,13. Because optical monitoring of neural activity is restricted by the limitations of light transmission7 to and from the neuronal population of interest, a miniscope was designed that requires an objective gradient refractive index (GRIN) lens (or objective lens) to be preanchored at the bottom of the miniscope to magnify the field of view that is relayed from a relay GRIN lens (or relay lens)6,7,8,10,16,17. This relay lens is implanted into the target brain region such that the fluorescence activity of the target brain region is relayed onto the surface of relay lens6,7,8,10,16,17. Approximately 1/4 of a full sinusoidal period of light travels through the objective GRIN lens (~ 0.25 pitch) (Figure 1A1), resulting in a magnified fluorescence image6,7. The objective lens is not always fixed at the bottom of the miniscope nor is the implantation of the relay lens necessary6,7,11,13,15. Specifically, there are two configurations: one with a fixed objective lens in the miniscope and a relay lens implanted in the brain8,10,12,14,16 (Figure 1B1) and another with just a removable objective lens6,7,11,13,15 (Figure 1B2). In the design based on the fixed objective and implanted relay lens combination, the fluorescence signals from the brain are brought to the top surface of the relay lens (Figure 1A1)7,8,10,12,14,16. Subsequently, the objective lens can magnify and transmit the visual field from the top surface of the relay lens (Figure 1A2). On the other hand, the removable objective GRIN lens design is more flexible, which means preimplantation of a relay lens into the brain is not mandatory (Figure 1B2)6,7,11,13,15. When using a miniscope based on a removable objective lens design, researchers still need to implant a lens into the target brain region but they can either implant an objective lens6,7,11,13,15 or a relay lens in the brain6,7. The choice of an objective or a relay lens for implantation determines the miniscope configuration that the researcher must use. For instance, the V3 UCLA Miniscope is based on a removable objective GRIN lens design. Researchers can choose either to directly implant an objective lens in the brain region of interest and mount the &#34;empty&#34; miniscope onto the objective lens6,7,11,13,15 (a one-lens system; Figure 1B2) or to implant a relay lens in the brain and mount a miniscope that is preanchored with an objective lens6,7 (a two-lens system; Figure 1B1). The miniscope then works as a fluorescence camera to capture livestream images of neuronal fluorescence produced by a genetically encoded calcium indicator1,2,3. After the miniscope is connected to a computer, these fluorescence images can be transferred to the computer and saved as video clips. Researchers can study neuronal activity by analyzing the relative changes in fluorescence with some analysis packages20,21 or write their codes for future analysis.
The V3 UCLA Miniscope provides flexibility for users to determine whether to image neuronal activity with a one- or two-lens system7. The choice of the recording system is based on the depth and size of the target brain area. In brief, a one-lens system can only image an area that is superficial (less than approximately 2.5 mm deep) and relatively large (larger than approximately 1.8 x 1.8 mm2) because the manufacturers only produce a certain size of objective lens. In contrast, a two-lens system can be applied to any target brain area. However, the dental cement for gluing the baseplate tends to cause misalignment with an altered distance between the objective and relay lenses, resulting in a poor image quality. If the two-lens system is being used, two working distances need to be precisely targeted to achieve the optimal imaging quality (Figure 1A). These two critical working distances are between the neurons and bottom surface of the relay lens, and between the top surface of the relay lens and the bottom surface of the objective lens (Figure 1A1). Any misalignment or misplacement of the lens outside of the working distance results in imaging failure (Figure 1C2). In contrast, the one-lens system requires only one precise working distance. However, objective lens size limits its application for monitoring of deep brain regions (the objective lens that fits the miniscope is approximately 1.8 ~ 2.0 mm6,11,13,15). Therefore, implantation of an objective lens is limited for the observation of the surface and relatively large brain regions, such as the cortex6,15 and dorsal cornu ammonis 1 (CA1) in mice11,13 . In addition, a large area of the cortex must be aspirated to target the dorsal CA111,13. Because of the limitation of the one-lens configuration that prevents imaging of deep brain regions, commercial miniscope systems offer only a combined objective lens/relay lens (two-lens) design. On the other hand, the V3 UCLA miniscope can be modified into either a one-lens or two-lens system because its objective lens is removable6,11,13,15. In other words, V3 UCLA miniscope users can take advantage of the removable lens by implanting it in the brain (creating a one-lens system), when performing experiments involving superficial brain observations (less than 2.5 mm in depth), or by preanchoring it in the miniscope and implanting a relay lens in the brain (creating a two-lens system), when performing experiments involving deep brain observations. The two-lens system can also be applied for superficially observing the brain, but the researcher must know the accurate working distances between the objective lens and relay lens. The main advantage of the one-lens system is that there is a decreased chance of missing the working distances than with a two-lens system, given that there are two working distances that need to be precisely targeted to achieve optimal imaging quality in the two-lens system (Figure 1A). Therefore, we recommend using a one-lens system for superficial brain observations. However, if the experiment requires imaging in the deep brain area, the researcher must learn to avoid misalignment of the two lenses.
The basic protocol for two-lens configuration of miniscopes for experiments includes lens implantation and baseplating8,10,16,17. Baseplating is the gluing of a baseplate onto an animal&#39;s head so that the miniscope can be eventually mounted on top of the animal and videotape the fluorescence signals of neurons (Figure 1B). This procedure involves using dental cement to glue the baseplate onto the skull (Figure 1C), but the shrinkage of dental cement can cause unacceptable changes in the distance between the implanted relay lens and the objective lens8,17. If the shifted distance between the two lenses is too large, cells cannot be brought into focus.
Detailed protocols for deep brain calcium imaging experiments using miniscopes have already been published8,10,16,17. The authors of these protocols have used the Inscopix system8,10,16 or other customized designs17 and have described the experimental procedures for viral selection, surgery, and baseplate attachment. However, their protocols cannot be precisely applied to other open-source systems, such as the V3 UCLA Miniscope system, NINscope6, and Finchscope19. Misalignment of the two lenses can occur during the recording in a two-lens configuration with a UCLA Miniscope due to the type of dental cement that is used to cement the baseplate to the skull8,17 (Figure 1C). The present protocol is needed because the distance between the implanted relay lens and the objective lens is prone to shift due to the undesirable shrinkage of dental cement during the baseplating procedure. During baseplating, the optimal working distance between the implanted relay lens and the objective lens must be found by adjusting the distance between the miniscope and the top of the relay lens, and the baseplate should then be glued at this ideal location. After the correct distance between the objective lens and the implanted relay lens is set, longitudinal measurements can be obtained at cellular resolution (Figure 1B; in vivo recording). Since the optimal range of working distances of a relay lens is small (50 - 350 &#181;m)4,8, excessive cement shrinkage during curing can make it difficult to keep the objective lens and the implanted relay lens within the appropriate range. The overall goal of this report is to provide a protocol to reduce the shrinkage problems8,17 that occur during the baseplating procedure and to increase the success rate of miniscope recordings of fluorescence signals in a two-lens configuration. Successful miniscope recording is defined as recording of a livestream of noticeable relative changes in the fluorescence of individual neurons in a freely behaving animal. Although different brands of dental cement have different shrinkage rates, researchers can select a brand that has been previously tested6,7,8,10,11,12,13,14,15,16,22. However, not every brand is easy to obtain in some countries/regions due to the import regulations for medical materials. Therefore, we have developed methods to test the shrinkage rates of available dental cements and, importantly provide an alternative protocol that minimizes the shrinkage problem. The advantage over the present baseplating protocol is an increase in the success rate of calcium imaging with tools and cement that can be easily obtained in laboratories. The UCLA miniscope is used as an example, but the protocol is also applicable to other miniscopes. In this report, we describe an optimized baseplating procedure and also recommend some strategies for fitting the UCLA miniscope two-lens system (Figure 2A). Both examples of successful implantation (n= 3 mice) and examples of failed implantation (n=2 mice) for the two-lens configuration with the UCLA miniscope are presented along with the discussions for the reasons of the successes and failures.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.7-mm drill bit</td>
			<td>&#160;#19008-07</td>
			<td>Fine Science Tools; USA</td>
			<td>for surgery</td>
		</tr>
		<tr>
			<td>0.1&#8211;10 &#956;l pipette tips</td>
			<td>104-Q; QSP</td>
			<td>Fisher Scientific; Singapore</td>
			<td>for testing dental cement</td>
		</tr>
		<tr>
			<td>20 G IV cathater</td>
			<td>#SR-OX2032CA</td>
			<td>Terumo Corporation; Tokyo, Japan</td>
			<td>for surgery</td>
		</tr>
		<tr>
			<td>27 G needle</td>
			<td>AGANI, AN*2713R</td>
			<td>Terumo Corporation; Tokyo, Japan</td>
			<td>for surgery</td>
		</tr>
		<tr>
			<td>AAV9-syn-jGCaMP7s-WPRE</td>
			<td>#104487-AAV9; 1.5*10^13</td>
			<td>Addgene viral prep; MA, USA</td>
			<td>for viral injection</td>
		</tr>
		<tr>
			<td>Atropine sulfate</td>
			<td></td>
			<td>Astart; Hsinchu, Taiwan</td>
			<td>for surgery/dummy baseplating/baseplating</td>
		</tr>
		<tr>
			<td>Baseplate</td>
			<td>V3</td>
			<td>http://miniscope.org</td>
			<td>for dummy baseplating/baseplating</td>
		</tr>
		<tr>
			<td>BLU TACK</td>
			<td>#30840350</td>
			<td>Bostik; Chelsea, Massachusetts, USA</td>
			<td>Reusable adhesive clay; for surgery/dummy baseplating/baseplating</td>
		</tr>
		<tr>
			<td>Bone Rongeur Friedman</td>
			<td>13 cm</td>
			<td>Diener; Tuttlingen, Germany</td>
			<td>for baseplating</td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td></td>
			<td>INDIVIOR; UK</td>
			<td>for surgery</td>
		</tr>
		<tr>
			<td>Carprofen</td>
			<td>Rimadyl</td>
			<td>Zoetis; Exton, PA</td>
			<td>analgesia</td>
		</tr>
		<tr>
			<td>Ceftazidime</td>
			<td></td>
			<td>Taiwan Biotech; Taiwan</td>
			<td>prevent infection</td>
		</tr>
		<tr>
			<td>Data Acquisition PCB for UCLA Miniscope</td>
			<td>purchased on https://www.labmaker.org/collections/neuroscience/products/data-aquistion-system-daq</td>
			<td></td>
			<td>for baseplating</td>
		</tr>
		<tr>
			<td>Dental cement set</td>
			<td>Tempron</td>
			<td>GC Corp; Tokyo, Japan</td>
			<td>for testing dental cement</td>
		</tr>
		<tr>
			<td>Dental cement set</td>
			<td>Tokuso Curefast</td>
			<td>Tokuyama Dental Corp.; Tokyo, Japan</td>
			<td>for testing dental cement/surgery/dummy baseplating/baseplating</td>
		</tr>
		<tr>
			<td>Dual Lab Standard with Mouse and Rat Adaptors</td>
			<td>#51673</td>
			<td>Stoelting Co; Illinois, USA</td>
			<td>for surgery/dummy baseplating/baseplating</td>
		</tr>
		<tr>
			<td>Duratear ointment</td>
			<td></td>
			<td>Alcon; Geneva, Switzerland</td>
			<td>for surgery/dummy baseplating/baseplating</td>
		</tr>
		<tr>
			<td>Ibuprofen</td>
			<td></td>
			<td>YungShin; Taiwan</td>
			<td>analgesia</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td></td>
			<td>Panion &#38; BF Biotech INC.; Taoyuan, Taiwan</td>
			<td>for surgery/dummy baseplating/baseplating</td>
		</tr>
		<tr>
			<td>Inscopix</td>
			<td>nVista System</td>
			<td>Inscopix; Palo Alto, CA</td>
			<td>for comparison with V3 UCLA Miniscope</td>
		</tr>
		<tr>
			<td>Ketamine</td>
			<td></td>
			<td>Pfizer; NY, NY</td>
			<td>for euthanasia</td>
		</tr>
		<tr>
			<td>Normal saline</td>
			<td></td>
			<td></td>
			<td>for surgery</td>
		</tr>
		<tr>
			<td>Micro bulldog clamps</td>
			<td>#12.102.04</td>
			<td>Dimedo; Tuttlingen, Germany</td>
			<td>for lens implantation</td>
		</tr>
		<tr>
			<td>Microliter Microsyringes, 2.0 &#181;L, 25 gauge</td>
			<td>#88400</td>
			<td>Hamilton; Bonaduz, Switzerland</td>
			<td>for viral injection</td>
		</tr>
		<tr>
			<td>Molding silicone rubber</td>
			<td>ZA22 Thixo</td>
			<td>Zhermack; Badia Polesine, Italy</td>
			<td>for dummy baseplating</td>
		</tr>
		<tr>
			<td>Objective Gradient index (GRIN) lens</td>
			<td>#64519</td>
			<td>Edmund Optics; NJ, USA</td>
			<td>for dummy baseplating/baseplating</td>
		</tr>
		<tr>
			<td>Parafilm</td>
			<td>#PM996</td>
			<td>Bemis; Neenah, USA</td>
			<td>for dummy baseplating</td>
		</tr>
		<tr>
			<td>Portable Suction</td>
			<td>#DF-750</td>
			<td>Doctor&#39;s Friend Medical Instrument Co., Inc., Taichung, Taiwan</td>
			<td>for surgery</td>
		</tr>
		<tr>
			<td>Relay GRIN lens</td>
			<td>#1050-002177</td>
			<td>Inscopix; Palo Alto, CA, USA</td>
			<td>for dummy baseplating/baseplating</td>
		</tr>
		<tr>
			<td>Stainless steel anchor screws</td>
			<td>1.00 mm diameter, total length 3.00 mm</td>
			<td></td>
			<td>for surgery</td>
		</tr>
		<tr>
			<td>Stereo microscope</td>
			<td>#SL720</td>
			<td>Sage Vison; New Taipei City, Taiwan</td>
			<td>for surgery/dummy baseplating/baseplating</td>
		</tr>
		<tr>
			<td>Stereotaxic apparatus</td>
			<td>#51673</td>
			<td>Stoelting; IL, USA</td>
			<td>for surgery/dummy baseplating/baseplating</td>
		</tr>
		<tr>
			<td>UV Cure Adhesive</td>
			<td>#3321</td>
			<td>Loctite; D&#252;sseldorf, Germany</td>
			<td>for testing dental cement</td>
		</tr>
		<tr>
			<td>V3 UCLA Miniscope</td>
			<td>purchased on https://www.labmaker.org/products/miniscope-complete-set-of-components</td>
			<td></td>
			<td>for surgery/dummy baseplating/baseplating</td>
		</tr>
		<tr>
			<td>Xylazine</td>
			<td>X1126</td>
			<td>Sigma-Aldrich; St. Louis, MO</td>
			<td>for euthanasia</td>
		</tr>
		<tr>
			<td>Xylocaine pump spray 10%</td>
			<td></td>
			<td>AstraZeneca; S&#246;dert&#228;lje, Sweden</td>
			<td>for surgery</td>
		</tr>
	</tbody>
</table>

using baseplating and a miniscope preanchored with an objective lens for calcium transient research in mice

Neuroscientists use miniature microscopes (miniscopes) to observe neuronal activity in freely behaving animals. The University of California, Los Angeles (UCLA) Miniscope team provides open resources for researchers to build miniscopes themselves. The V3 UCLA Miniscope is one of the most popular open-source miniscopes currently in use. It permits imaging of the fluorescence transients emitted from genetically modified neurons through an objective lens implanted on the superficial cortex (a one-lens system), or in deep brain areas through a combination of a relay lens implanted in the deep brain and an objective lens that is preanchored in the miniscope to observe the relayed image (a two-lens system). Even under optimal conditions (when neurons express fluorescence indicators and the relay lens has been properly implanted), a volume change of the dental cement between the baseplate and its attachment to the skull upon cement curing can cause misalignment with an altered distance between the objective and relay lenses, resulting in the poor image quality. A baseplate is a plate that helps mount the miniscope onto the skull and fixes the working distance between the objective and relay lenses. Thus, changes in the volume of the dental cement around the baseplate alter the distance between the lenses. The present protocol aims to minimize the misalignment problem caused by volume changes in the dental cement. The protocol reduces the misalignment by building an initial foundation of dental cement during relay lens implantation. The convalescence time after implantation is sufficient for the foundation of dental cement to cure the baseplate completely, so the baseplate can be cemented on this scaffold using as little new cement as possible. In the present article, we describe strategies for baseplating in mice to enable imaging of neuronal activity with an objective lens anchored in the miniscope.

Assessment of the dental cement volume alteration 
Since the volume of dental cement changes during the curing process, it may significantly impact the imaging quality, given that the working distance of a GRIN lens is approximately 50 to 350 &#181;m4,8. Therefore, two commercially available dental cements were tested in this case, Tempron and Tokuso, before the implantation and baseplating procedure (Figure 5)....

Watch this Scientific Journal Video about Using Baseplating and a Miniscope Preanchored with an Objective Lens for Calcium Transient Research in Mice at JoVE.com

Using Baseplating and a Miniscope Preanchored with an Objective Lens for Calcium Transient Research in Mice

The shrinkage of dental cement during curing displaces the baseplate. This protocol minimizes the problem by creating an initial foundation of the dental cement that leaves space to cement the baseplate. Weeks later, the baseplate can be cemented in position on this scaffold using little new cement, therebyreducing shrinkage.

Neuroscientists use miniature microscopes (miniscopes) to observe neuronal activity in freely behaving animals. The University of California, Los Angeles ...

This miniscope can reduce the shrinkage problem with dental cement during the baseplate procedure and increase the success rate of miniscope recordings of fluorescence signals in two length configuration. If the fluorescence transient cannot be observed during baseplating, check the expression of calcium indicator and location of a relay lens on the brain slice. Start with mounting the inner needle of a 20 gauge intravenous catheter with a diameter of one millimeter onto the stereotaxic arm.Lower the catheter into the ventral corn ammonis 1 into the target region. Then, lower the microinjection needle at a speed of 100 to 200 micrometers per minute into the ventral cornu ammonis 1, and infuse 200 nanoliters of the viral vector into the target region at a speed of 25 nanoliters per minute. After allowing the virus to diffuse for 10 minutes, withdraw the microinjection needle at a speed of 100 to 200 micrometers per minute.After disinfecting the relay lens, soak the lens in cold pyrogen-free saline until implantation. Using a micro bulldog clamp with heat shrink tubing, hold the relay lens and place it on top of the target region at a speed of 100 to 200 micrometers per minute. Then, stabilize the lens with dental cement.To set a miniscope, fasten the objective lens on the bottom and assemble the base plate onto the miniscope. Wrap 10 centimeters of paraffin film around the outside of the baseplate. Using reusable adhesive clay, hold the miniscope with the stereotaxic arm probe.Align the objective lens on top of the relay lens with as little space between the lenses as possible. Use dental cement to secure the positioning of the baseplate, such that the cement touches only the paraffin film. When the dental cement has dried, remove the paraffin film, the base plate, and the miniscope, keeping the dental cement base hollow.Seal the relay lens with molding silicone rubber and cover the silicone rubber with a thin layer of dental cement. Disengage the mouse from the stereotaxic instruments and place the mouse into a recovery chamber. For baseplating, cut the thin layer of the dental cement roof carefully with a bone rongeur and remove the silicone rubber.Clean the surface of the relay lens with 75%alcohol. Fasten the set screw beside the baseplate to fix it to the bottom of the miniscope. Adjust the focus slide to be approximately 2.7 to 3 millimeters from the main housing.When the setting is done, connect the miniscope to the data acquisition board and plug the miniscope into a USB 3.0 port on a computer. Run the data acquisition software developed by the UCLA team. Adjust the exposure to 255, the gain to 64x and the excitation LED to 5%To connect the miniscope to the data acquisition software, click the connect button and watch the livestream of the data acquisition software considering the margin of the relay lens as a landmark.Once the relay lens is found, align the miniscope objective lens to the relay lens by hand. Adjusting the various angles and distances of the miniscope, begin searching for the fluorescence signals. Holding the miniscope at the optimal position, move the stereotaxic arm towards the mini scope and adhere the miniscope to the stereotaxic arm with reusable adhesive clay.Search for the best view by adjusting the X, Y, and Z arms slightly. Adjust the angle between the surface of the objective lens and relay lens by turning the ear bar, tooth bar, or reusable adhesive clay on the Z axis. Viral expression and lens implantation are successful when at least one cell displaced fluorescence transients during baseplating.Fix the base plate firmly with the smallest possible amount of dental cement while monitoring the region of interest to ensure that the optimal position does not change. In the representative study, the procedure of dummy baseplating proved advantageous as it resulted in a smaller shift in the baseplate location than the original procedure. The shift of the baseplate was also influenced by the height of the dental cement.The baseplate that was anchored 0.5 centimeters above the skull shifted significantly less than the baseplate that was fixed one centimeter above the skull. In an example of successful imaging during the base plating procedure fluorescence transients along with blood vessels were noticed in the anesthetized animal. Fluorescence transients were observed five days after baseplating even when the mouse was freely behaving in its home cage with only a slight shift in a position.Subsequent calcium imaging of mice was carried out. In a few instances, problems occurred during the baseplating procedure, such as the absence of anything except a uniform background or visibility of white cell margins. without fluorescence transients.It is important to fix the baseplate firmly on the target region with the smallest possible amount of dental cement. With slate technique, researchers can longitudinally observe neural activity across this. With the proper license, this procedure can also apply to observe the neural network in the field of view.

using-baseplating-miniscope-preanchored-with-an-objective-lens-for

Research

JoVE Journal

Neuroscience

A Simple and Inexpensive Method for Determining Cold Sensitivity and Adaptation in Mice

Cold hypersensitivity is a serious clinical problem, affecting a broad subset of patients and causing significant decreases in quality of life. The cold plantar assay allows the objective and inexpensive assessment of cold sensitivity in mice, and can quantify both analgesia and hypersensitivity. Mice are acclimated on a glass plate, and a compressed dry ice pellet is held against the glass surface underneath the hindpaw. The latency to withdrawal from the cooling glass is used as a measure of cold sensitivity.
Cold sensation is also important for survival in regions with seasonal temperature shifts, and in order to maintain sensitivity animals must be able to adjust their thermal response thresholds to match the ambient temperature. The Cold Plantar Assay (CPA) also allows the study of adaptation to changes in ambient temperature by testing the cold sensitivity of mice at temperatures ranging from 30 &#176;C to 5 &#176;C. Mice are acclimated as described above, but the glass plate is cooled to the desired starting temperature using aluminum boxes (or aluminum foil packets) filled with hot water, wet ice, or dry ice. The temperature of the plate is measured at the center using a filament T-type thermocouple probe. Once the plate has reached the desired starting temperature, the animals are tested as described above.
This assay allows testing of mice at temperatures ranging from innocuous to noxious. The CPA yields unambiguous and consistent behavioral responses in uninjured mice and can be used to quantify both hypersensitivity and analgesia. This protocol describes how to use the CPA to measure cold hypersensitivity, analgesia, and adaptation in mice.

The Cold Plantar Assay (CPA) measures cold responsiveness between 30 &#176;C and 5 &#176;C, and can also measure cold adaptation. This protocol describes how to use the CPA to measure cold hypersensitivity, analgesia, and adaptation in mice.

Cold hypersensitivity is a serious clinical problem, affecting a broad subset of patients and causing significant decreases in quality of life.  The cold ...

Denver Papillae Protocol for Objective Analysis of Fungiform Papillae

The goal of the Denver Papillae Protocol is to use a dichotomous key to define and prioritize the characteristics of fungiform papillae (FP) to ensure consistent scoring between scorers. This protocol builds off of a need that has arisen from the last two decades of taste research using FP as a proxy for taste pore density. FP density has historically been analyzed using Miller &#38; Reedy&#8217;s 1990 characterizations of their morphology: round, stained lighter, large, and elevated. In this work, the authors forewarned that stricter definitions of FP morphology needed to be outlined. Despite this call to action, follow up literature has been scarce, with most studies continuing to cite Miller &#38; Reedy&#8217;s original work. Consequently, FP density reports have been highly variable and, combined with small sample sizes, may contribute to the discrepant conclusions on the role of FP in taste sensitivity. The Genetics of Taste Lab explored this apparent inconsistency in counting and found that scorers were individually prioritizing the importance of these characteristics differently and had no guidance for when a papilla had some, but not all, of the reported qualities of FP. The result of this subjectivity is highly variable FP counts of the same tongue image. The Denver Papillae Protocol has been developed to remedy this consequence through use of a dichotomous key that further defines and prioritizes the importance of the characteristics put forth by Miller &#38; Reedy. The proposed method could help create a standard way to quantify FP for researchers in the field of taste and nutritional studies.

Here we present a protocol to measure fungiform papilla density from digital photographs. This method builds prioritization and objective characteristic metrics into the original descriptive work on fungiform papillae by Miller &#38; Reedy (1990).

The goal of the Denver Papillae Protocol is to use a dichotomous key to define and prioritize the characteristics of fungiform papillae (FP) to ensure ...

Extracellular Recording of Neuronal Activity Combined with Microiontophoretic Application of Neuroactive Substances in Awake Mice

Differences in the activity of neurotransmitters and neuromodulators, and consequently different neural responses, can be found between anesthetized and awake animals. Therefore, methods allowing the manipulation of synaptic systems in awake animals are required in order to determine the contribution of synaptic inputs to neuronal processing unaffected by anesthetics. Here, we present methodology for the construction of electrodes to simultaneously record extracellular neural activity and release multiple neuroactive substances at the vicinity of the recording sites in awake mice. By combining these procedures, we performed microiontophoretic injections of gabazine to selectively block GABAA receptors in neurons of the inferior colliculus of head-restrained mice. Gabazine successfully modified neural response properties such as the frequency response area and stimulus-specific adaptation. Thus, we demonstrate that our methods are suitable for recording single-unit activity and for dissecting the role of specific neurotransmitter receptors in auditory processing.
The main limitation of the described procedure is the relatively short recording time (~3 hr), which is determined by the level of habituation of the animal to the recording sessions. On the other hand, multiple recording sessions can be performed in the same animal. The advantage of this technique over other experimental procedures used to manipulate the level of neurotransmission or neuromodulation (such as systemic injections or the use of optogenetic models), is that the drug effect is confined to the local synaptic inputs to the target neuron. In addition, the custom-manufacture of electrodes allows adjustment of specific parameters according to the neural structure and type of neuron of interest (such as the tip resistance for improving the signal-to-noise ratio of the recordings).

We present methods for the construction of electrodes to simultaneously record extracellular neural activity and release multiple neuroactive substances at the vicinity of the recording sites in awake mice. This technique allows the detailed analysis of putative local synaptic inputs to the neuron of interest.

Differences in the activity of neurotransmitters and neuromodulators, and consequently different neural responses, can be found between anesthetized and ...

Loading a Calcium Dye into Frog Nerve Endings Through the Nerve Stump: Calcium Transient Registration in the Frog Neuromuscular Junction

One of the most feasible methods of measuring presynaptic calcium levels in presynaptic nerve terminals is optical recording. It is based on using calcium-sensitive fluorescent dyes that change their emission intensity or wavelength depending on the concentration of free calcium in the cell. There are several methods used to stain cells with calcium dyes. Most common are the processes of loading the dyes through a micropipette or pre-incubating with the acetoxymethyl ester forms of the dyes. However, these methods are not quite applicable to neuromuscular junctions (NMJs) due to methodological issues that arise. In this article, we present a method for loading a calcium-sensitive dye through the frog nerve stump of the frog nerve into the nerve endings. Since entry of external calcium into nerve terminals and the subsequent binding to the calcium dye occur within the millisecond time-scale, it is necessary to use a fast imaging system to record these interactions. Here, we describe a protocol for recording the calcium transient with a fast CCD camera.

Here, we describe a method for loading a calcium-sensitive dye through the frog nerve stump into the nerve endings. We also present a protocol for the recording and analysis of fast calcium transients in the peripheral nerve endings.

One of the most feasible methods of measuring presynaptic calcium levels in presynaptic nerve terminals is optical recording. It is based on using ...

An In Vivo Blood-brain Barrier Permeability Assay in Mice Using Fluorescently Labeled Tracers

Blood-brain barrier (BBB) is a specialized barrier that protects the brain microenvironment from toxins and pathogens in the circulation and maintains brain homeostasis. The principal sites of the barrier are endothelial cells of the brain capillaries whose barrier function results from tight intercellular junctions and efflux transporters expressed on the plasma membrane. This function is regulated by pericytes and astrocytes that together form the neurovascular unit (NVU). Several neurological diseases such as stroke, Alzheimer&#39;s disease (AD), brain tumors are associated with an impaired BBB function. Assessment of the BBB permeability is therefore crucial in evaluating the severity of the neurological disease and the success of the treatment strategies employed.
We present here a simple yet robust permeability assay that have been successfully applied to several mouse models both, genetic and experimental. The method is highly quantitative and objective in comparison to the tracer fluorescence analysis by microscopy that is commonly applied. In this method, mice are injected intraperitoneally with a mix of aqueous inert fluorescent tracers followed by anesthetizing the mice. Cardiac perfusion of the animals is performed prior to harvesting brain, kidneys or other organs. Organs are homogenized and centrifuged followed by fluorescence measurement from the supernatant. Blood drawn from the cardiac puncture just before perfusion serves for normalization purpose to the vascular compartment. The tissue fluorescence is normalized to the wet weight and serum fluorescence to obtain a quantitative tracer permeability index. For additional confirmation, the contralateral hemi-brain preserved for immunohistochemistry can be utilized for tracer fluorescence visualization purposes.

An In Vivo Blood-brain Barrier Permeability Assay in Mice Using Fluorescently Labeled Tracers

Here we present a mouse brain vascular permeability assay using intraperitoneal injection of fluorescent tracers followed by perfusion that is applicable to animal models of blood-brain barrier dysfunction. One hemi-brain is used for assessing permeability quantitatively and the other for tracer visualization/immunostaining. The procedure takes 5 - 6 h for 10 mice.

Blood-brain barrier (BBB) is a specialized barrier that protects the brain microenvironment from toxins and pathogens in the circulation and maintains ...

An Objective and Reproducible Test of Olfactory Learning and Discrimination in Mice

Olfaction is the predominant sensory modality in mice and influences many important behaviors, including foraging, predator detection, mating, and parenting. Importantly, mice can be trained to associate novel odors with specific behavioral responses to provide insight into olfactory circuit function. This protocol details the procedure for training mice on a Go/No-Go operant learning task. In this approach, mice are trained on hundreds of automated trials daily for 2&#8211;4 weeks and can then be tested on novel Go/No-Go odor pairs to assess olfactory discrimination, or be used for studies on how odor learning alters the structure or function of the olfactory circuit. Additionally, the mouse olfactory bulb (OB) features ongoing integration of adult-born neurons. Interestingly, olfactory learning increases both the survival and synaptic connections of these adult-born neurons. Therefore, this protocol can be combined with other biochemical, electrophysiological, and imaging techniques to study learning and activity-dependent factors that mediate neuronal survival and plasticity.

Here, we train mice on an associative learning task to test odor discrimination. This protocol also allows for studies on learning-induced structural changes in the brain.

Olfaction is the predominant sensory modality in mice and influences many important behaviors, including foraging, predator detection, mating, and ...

Ablation of a Neuronal Population Using a Two-photon Laser and Its Assessment Using Calcium Imaging and Behavioral Recording in Zebrafish Larvae

To identify the role of a subpopulation of neurons in behavior, it is essential to test the consequences of blocking its activity in living animals. Laser ablation of neurons is an effective method for this purpose when neurons are selectively labeled with fluorescent probes. In the present study, protocols for laser ablating a subpopulation of neurons using a two-photon microscope and testing of its functional and behavioral consequences are described. In this study, prey capture behavior in zebrafish larvae is used as a study model. The pretecto-hypothalamic circuit is known to underlie this visually-driven prey catching behavior. Zebrafish pretectum were laser-ablated, and neuronal activity in the inferior lobe of the hypothalamus (ILH; the target of the pretectal projection) was examined. Prey capture behavior after pretectal ablation was also tested.

Here, we present a protocol to ablate a genetically labeled subpopulation of neurons by a two-photon laser from Zebrafish larvae.

To identify the role of a subpopulation of neurons in behavior, it is essential to test the consequences of blocking its activity in living animals. Laser ...

A High-throughput Calcium-flux Assay to Study NMDA-receptors with Sensitivity to Glycine/D-serine and Glutamate

N-methyl-D-aspartate (NMDA) receptors (NMDAR) are classified as ionotropic glutamate receptors and have critical roles in learning and memory. NMDAR malfunction, expressed as either over- or under-activity caused by mutations, altered expression, trafficking, or localization, can contribute to numerous diseases, especially in the central nervous system. Therefore, understanding the receptor&#39;s biology as well as facilitating the discovery of compounds and small molecules is crucial in ongoing efforts to combat neurological diseases. Current approaches to studying the receptor have limitations including low throughput, high cost, and the inability to study its functional abilities due to the necessary presence of channel blockers to prevent NMDAR-mediated excitotoxicity. Additionally, the existing assay systems are sensitive to stimulation by glutamate only and lack sensitivity to stimulation by glycine, the other co-ligand of the NMDAR. Here, we present the first plate-based assay with high-throughput power to study an NMDA receptor with sensitivity to both co-ligands, glutamate and D-serine/glycine. This approach allows the study of different NMDAR subunit compositions and allows functional studies of the receptor in glycine- and/or glutamate-sensitive modes. Additionally, the method does not require the presence of inhibitors during measurements. The effects of positive and negative allosteric modulators can be detected with this assay and the known pharmacology of NMDAR has been replicated in our system. This technique overcomes the limitations of existing methods and is cost-effective. We believe that this novel technique will accelerate the discovery of therapies for NMDAR-mediated pathologies.

The goal of this protocol is to facilitate the study of NMDA-receptors (NMDAR) at a larger scale and allow the examination of modulatory effects of small molecules and their therapeutic applications.

N-methyl-D-aspartate (NMDA) receptors (NMDAR) are classified as ionotropic glutamate receptors and have critical roles in learning and memory. NMDAR ...

Successful In vivo Calcium Imaging with a Head-Mount Miniaturized Microscope in the Amygdala of Freely Behaving Mouse

In vivo real-time monitoring of neuronal activities in freely moving animals is one of key approaches to link neuronal activity to behavior. For this purpose, an in vivo imaging technique that detects calcium transients in neurons using genetically encoded calcium indicators (GECIs), a miniaturized fluorescence microscope, and a gradient refractive index (GRIN) lens has been developed and successfully applied to many brain structures1,2,3,4,5,6. This imaging technique is particularly powerful because it enables chronic simultaneous imaging of genetically defined cell populations for a long-term period up to several weeks. Although useful, this imaging technique has not been easily applied to brain structures that locate deep within the brain such as amygdala, an essential brain structure for emotional processing and associative fear memory7. There are several factors that make it difficult to apply the imaging technique to the amygdala. For instance, motion artifacts usually occur more frequently during the imaging conducted in the deeper brain regions because a head-mount microscope implanted deep in the brain is relatively unstable. Another problem is that the lateral ventricle is positioned close to the implanted GRIN lens and its movement during respiration may cause highly irregular motion artifacts that cannot be easily corrected, which makes it difficult to form a stable imaging view. Furthermore, because cells in the amygdala are usually quiet at a resting or anesthetized state, it is hard to find and focus the target cells expressing GECI in the amygdala during baseplating procedure for later imaging. This protocol provides a helpful guideline for how to efficiently target cells expressing GECI in the amygdala with head-mount miniaturized microscope for successful in vivo calcium imaging in such a deeper brain region. It is noted that this protocol is based on a particular system (e.g., Inscopix) but not restricted to it.

In vivo microendoscopic calcium imaging is an invaluable tool that enables real-time monitoring of neuronal activities in freely behaving animals. However, applying this technique to the amygdala has been difficult. This protocol aims to provide a useful guideline for successfully targeting amygdala cells with a miniaturized microscope in mice.

In vivo real-time monitoring of neuronal activities in freely moving animals is one of key approaches to link neuronal activity to behavior. For this ...

Electrocorticographic Recording of Cerebral Cortex Areas Manipulated Using an Adeno-Associated Virus Targeting Cofilin in Mice

The use of electrocorticographic (ECoG) recordings in rodents is relevant to sleep research and to the study of a wide range of neurological conditions. Adeno-associated viruses (AAVs) are increasingly used to improve understanding of brain circuits and their functions. The AAV-mediated manipulation of specific cell populations and/or of precise molecular components has been tremendously useful to identify new sleep regulatory circuits/molecules and key proteins contributing to the adverse effects of sleep loss. For instance, inhibiting activity of the filamentous actin-severing protein&#160;cofilin&#160;using AAV prevents sleep deprivation-induced memory impairment. Here, a protocol is&#160;described that combines the manipulation of cofilin function in a cerebral cortex area with the recording of ECoG activity to examine whether cortical cofilin modulates the wakefulness and sleep ECoG signals. AAV injection is performed during the same surgical procedure as the implantation of ECoG and electromyographic (EMG) electrodes in adult male and female mice. Mice are anesthetized, and their heads are shaved. After skin cleaning and incision, stereotaxic coordinates of the motor cortex are determined, and the skull is pierced at this location. A cannula prefilled with an AAV expressing cofilinS3D, an inactive form of cofilin, is slowly positioned in the cortical tissue. After AAV infusion, gold-covered screws (ECoG electrodes) are screwed through the skull and cemented to the skull with gold wires inserted in the neck muscles (EMG electrodes). The animals are allowed three weeks to recover and to ensure sufficient expression of cofilinS3D. The infected area and cell type are verified using immunohistochemistry, and the ECoG is analyzed using visual identification of vigilance states and spectral analysis. In summary, this combined methodological approach allows the investigation of the precise contribution of molecular components regulating neuronal morphology and connectivity to the regulation of synchronized cerebral cortex activity during wakefulness and sleep.

This article describes a protocol for the manipulation of molecular targets in the cerebral cortex using adeno-associated viruses and for monitoring the effects of this manipulation during wakefulness and sleep using electrocorticographic recordings.

The use of electrocorticographic (ECoG) recordings in rodents is relevant to sleep research and to the study of a wide range of neurological conditions. ...