The research in this report was funded by a target grant from the NIGMS (1P20GM103653) awarded to DK.

The following protocol was approved by the Institutional Animal Care and Use Committee (IACUC) of the University of Delaware. Male Sprague Dawley rats approximately 55&#8211;75 days old were used for this protocol.
1. Brain Extraction and Tissue Preparation
<ol>
	<li>Anesthetize rat with isoflurane in anesthesia induction chamber until rat no longer exhibits a response to foot pinch.</li>
	<li>Sacrifice rats via rapid decapitation using a guillotine.</li>
	<li>Cut skin on skull posterior to anterior and clear from top of skull.</li>
	<li>Use rongeurs to carefully remove the back part of skull, and then using small dissecting scissors cut down midline of skull, pushing upward against the top of skull at all times to avoid damaging the brain tissue.</li>
	<li>Use rongeurs to peel away right and left half of skull to expose the brain.</li>
	<li>Use a small spatula to scoop under brain and sever nerves, carefully elevate brain and freeze brains in isopentane chilled on dry ice (at least -20 &#176;C). After this, store brains in a -80 &#176;C freezer until slicing.</li>
	<li>Slice brains in regions of interest at 30&#8211;50 &#181;m in a cryostat maintained between -9 &#176;C and -12 &#176;C. Directly mount slices onto glass slides and store in a -80 &#176;C freezer until time of immunocytochemistry assay. 
	NOTE: In this protocol brain regions of interest were the hippocampus and the amygdala.</li>
</ol>
2. Single Immunohistochemical Reaction
NOTE: For double immunohistochemical reaction, the protocol is the same as the single immunohistochemical reaction except this reaction has two primary antibodies of different hosts (e.g., rabbit and mouse) and two secondary antibodies for the corresponding primaries should be from a single host (e.g., goat antirabbit and goat antimouse). The secondary antibodies also have to be from two different spectra that are available in high-resolution scanners. For example, one secondary antibody with an emission spectrum peak at 680 nm and one secondary antibody 800CW (emission spectrum peak at 780 nm).
<ol>
	<li>Remove glass slides from the freezer and allow to equilibrate to room temperature for 30 min.</li>
	<li>Under a fume hood, fix brain tissue in 4% paraformaldehyde in 0.1 M phosphate buffered saline (PBS) for 1&#8722;2 h at room temperature.</li>
	<li>Rinse slides in 0.1 M tris buffered saline (TBS) three times for 10 min each. Permeabilize cell membranes by incubating slides in a mild detergent (e.g., 0.01% detergent) for 30&#8722;60 min.</li>
	<li>Rinse slides in TBS three times for 15 min each.</li>
	<li>Dilute primary antibody for protein of interest in PBS in the correct concentration. For example, to detect the immediate early gene c-Fos, prepare a rabbit primary anti c-Fos antibody in a concentration of 1:500.</li>
	<li>Pipette primary antibody solution directly onto the brain tissue (approximately 200 &#181;L per 3 inch x 1 inch slide).</li>
	<li>Use coverslips to incubate the brain tissue on glass slides in primary antibody dilution for either 1&#8722;2 h at room temperature or overnight (~17 h) at 4 &#176;C.</li>
	<li>Remove coverslips and wash slides in TBS that has a small amount of detergent added to it (e.g., 0.01% detergent, &#34;TBS-T&#34;) four times for 15 min each.</li>
	<li>Use coverslips to incubate brain sections in a secondary antibody at room temperature for 2 h. 
	NOTE: The secondary antibody has to be to the correct dilution and in a diluent containing TBS, detergent, and 1.5% of host serum. For example, a goat secondary antibody in a dilution of 1:2,000 would contain 1.5% goat serum and 0.05% detergent.</li>
	<li>Rinse slides in TBS-T four times for 20 min each, and then in TBS four times for 20 min each.</li>
	<li>Dry slides at room temperature in the dark overnight. When slides are dry, they are ready for imaging.</li>
</ol>
3. Imaging
<ol>
	<li>Place slides onto the near-infrared scanning interface with the tissue facing down. Either image one glass slide or multiple slides at a time using a selection tool.</li>
	<li>Image slides using the highest quality setting with an offset of 0 nm and a resolution of 21 &#181;m. The scanning will typically take 13&#8722;19 h depending on the scanning equipment used.</li>
	<li>Import images into the image analysis software (e.g., ImageStudio) to view and mark for semi-quantitative protein analysis.</li>
</ol>
4. Protein Expression Analysis
<ol>
	<li>Open the image analysis software and select the Work Area into which the image was scanned.</li>
	<li>Open the scanned image in the image analysis software to view the scan, and adjust which wavelengths are viewed, as well as the contrast, brightness, and magnification shown without altering the raw image or the total quantified emission.</li>
	<li>Identify the key regions for quantification and select the Analysis tab along the top of the page, then select Draw Rectangle (or Draw Ellipse/ Draw Freehand) to draw a rectangle over the area that will be quantified.</li>
	<li>To view the size of the rectangle, select Shapes along the bottom left of the screen, then select Columns along bottom right. Add Height and Width columns to identify the shape size. 
	NOTE: It is important to control for shape size when comparing quantification. It is recommended to use identical shapes placed within the desired quantification location, in order to get an accurate sampling of the emissions for that region.</li>
	<li>Then name the shape and repeat. Once all regions are sampled the data available from the columns tab can be aggregated and analyzed.</li>
</ol>

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	<li>Kandel, E. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Principles of Neural Science. , (2013).</li><li>Byrne, J. H., Roberts, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> From Molecules to Networks: An Introduction to Cellular and Molecular Neuroscience. , (2009).</li><li>Salami, 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=Dopamine+D2/3+binding+potential+modulates+neural+signatures+of+working+memory+in+a+load-dependent+fashion.">Dopamine D2/3 binding potential modulates neural signatures of working memory in a load-dependent fashion.</a> Journal of Neuroscience. , (2018).</li><li>Merali, Z., Khan, S., Michaud, D. S., Shippy, S. A., Anisman, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Does+amygdaloid+corticotropin-releasing+hormone+(CRH)+mediate+anxiety-like+behaviors?+Dissociation+of+anxiogenic+effects+and+CRH+release.">Does amygdaloid corticotropin-releasing hormone (CRH) mediate anxiety-like behaviors? Dissociation of anxiogenic effects and CRH release.</a> European Journal of Neuroscience. 20 (1), 229-239 (2004).</li><li>English, J. 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=Dataset+of+mouse+hippocampus+profiled+by+LC-MS/MS+for+label-free+quantitation.">Dataset of mouse hippocampus profiled by LC-MS/MS for label-free quantitation.</a> Data in Brief. 7, 341-343 (2016).</li><li>David, M. A., Tayebi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+protein+aggregates+in+brain+and+cerebrospinal+fluid+derived+from+multiple+sclerosis+patients.">Detection of protein aggregates in brain and cerebrospinal fluid derived from multiple sclerosis patients.</a> Frontiers in Neurology. 5, 251 (2014).</li><li>Oliver, C., Jamur, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunocytochemical+methods+and+protocols.">Immunocytochemical methods and protocols.</a> Methods in Molecular Biology. , (2010).</li><li>Spitzer, N., Sammons, G. S., Price, E. 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The authors have nothing to disclose.

The results presented in this article show that near-infrared immunocytochemistry in combination with high-resolution scanning can be used to obtain semi-quantitative measures of protein expression in brain tissue. It can also be used to label two proteins simultaneously in the same brain region. We have previously used near-infrared immunohistochemistry to measure immediate early gene expression in multiple brain regions9,10. Immediate early genes can be used as...

The study of neuroscience concerns an investigation of how cells in the brain mediate specific functions1. These can be cellular in nature such as how glia cells confer immunity in the central nervous system or can involve experiments that aim to explain how the activity of neurons in the dorsal hippocampus leads to spatial navigation. In a broad sense, cellular function is determined by the proteins that are expressed in a cell and the activity of these proteins2. As a result, measuring the expression and/or activity of proteins in brain cells are critical for the study of neuroscience.
A number of techniques are available to measure protein expression in the brain. These include in vivo methods such as positron emission topography for receptor densities3 and micro-dialysis for small peptides4. More commonly, ex vivo methods are used to examine protein function and expression. These include mass spectrometry techniques5, western blot and enzyme-linked immunosorbent assay (ELISA)6, and immunocytochemistry7. Immunocytochemistry is widely used in the field of neuroscience. This technique involves the use of a primary antibody to detect a protein (or antigen) of interest (e.g., c-Fos) and a conjugated secondary antibody to detect the protein-primary antibody complex (Figure 1). To enable detection of the protein-primary antibody-secondary antibody complex, secondary antibodies have oxidizing agents such as horseradish peroxidase (HRP) conjugated to them. This allows for the formation of precipitates in cells that can be detected using light microscopy7. Secondary antibodies can also have chemicals fluoresce conjugated to them (i.e., fluorophores). When stimulated these chemicals emit light, which can be used to detect protein-primary antibody-secondary antibody complexes7. Lastly, sometimes primary antibodies have reducing agents and fluorescence chemicals attached to them directly negating the need for secondary antibodies7 (Figure 1).
Interestingly, many immunocytochemistry methods allow for visualization of proteins in brain cells, but not the ability to quantify the amount of protein in a specific cell or brain region. Using light microscopy to detect precipitates from reduction reactions allows for visualization of neurons and glia, but this method cannot be used to quantify protein expression in cells or in a specific brain region. In theory, fluorescence microscopy can be used for this, because the light emitted from the fluorescent secondary antibody is a measure of the protein-primary antibody-secondary antibody complex. However, autofluorescence in brain tissue can make it difficult to use fluorescence microscopy to quantify protein expression in brain tissue8. As a result, light emitted from fluorescent images of brain tissue is rarely used to quantify protein expression in the brain.
Many of these issues can be addressed using near-infrared immunocytochemistry in conjunction with high-resolution scanning9,10. In this article, we describe how immunocytochemistry coupled with fluorophores in the near-infrared emission spectra can be combined with high resolution scanning (e.g., 10&#8211;21 &#181;m) to obtain sharp images that allow for semi quantification of protein in distinct brain regions.

<table border="0" cellpadding="0" cellspacing="0" style="width:658px;" width="657">
	<tbody>
		<tr height="21">
			<td colspan="4" height="21" style="height:21px;width:658px;">Brain Extraction</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:207px;">Anesthesia Induction Chamber</td>
			<td style="width:147px;">Kent Scientific</td>
			<td>VetFlo-0530SM</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Kleine Guillotine</td>
			<td style="width:147px;">Harvard Apparatus</td>
			<td>73-1920</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Friedman Rongeur</td>
			<td style="width:147px;">Fine Science Tools</td>
			<td>16000-14</td>
			<td>used to remove back of skull</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Delicate Dissecting Scissors</td>
			<td style="width:147px;">Fischer Scientific</td>
			<td>08-951-5</td>
			<td>used to cut upward along midline of skull</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Micro Spatula</td>
			<td style="width:147px;">Fischer Scientific</td>
			<td>21-401-5</td>
			<td>used to scoop out brain</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Glass Microscope Slides</td>
			<td style="width:147px;">Fischer Scientific</td>
			<td style="width:114px;">12-549-6</td>
			<td></td>
		</tr>
		<tr height="21">
			<td colspan="4" height="21" style="height:21px;width:658px;">Immunohistochemical Reaction</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">&#160;Triton X-100</td>
			<td style="width:147px;"></td>
			<td style="width:114px;"></td>
			<td>Used as a mild detergent to permeabilize cells after fixing in Paraformaldehyde, also used as mild detergent in combination with host serum and secondary antibody&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Tween-20</td>
			<td style="width:147px;"></td>
			<td style="width:114px;"></td>
			<td>Used as a small amount of detergent added to TBS&#160; to procuce TBS-T after coverslipping slides with primary antibody</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:207px;">Licor Odyssey scanner</td>
			<td style="width:147px;">Licor Biotechnology Inc.</td>
			<td style="width:114px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:207px;">Image Studio</td>
			<td style="width:147px;">Licor Biotechnology Inc.</td>
			<td style="width:114px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

using near-infrared fluorescence and high-resolution scanning to measure protein expression in the rodent brain

Neuroscience is the study of how cells in the brain mediate various functions. Measuring protein expression in neurons and glia is critical for the study of neuroscience as cellular function is determined by the composition and activity of cellular proteins. In this article, we describe how immunocytochemistry can be combined with near-infrared high-resolution scanning to provide a semi-quantitative measure of protein expression in distinct brain regions. This technique can be used for single or double protein expression in the same brain region. Measuring proteins in this fashion can be used to obtain a relative change in protein expression with an experimental manipulation, molecular signature of learning and memory, activity in molecular pathways, and neural activity in multiple brain regions. Using the correct proteins and statistical analysis, functional connectivity among brain regions can be determined as well. Given the ease of implementing immunocytochemistry in a laboratory, using immunocytochemistry with near-infrared high-resolution scanning can expand the ability of the neuroscientist to examine neurobiological processes at a systems level.

Prior to using high-resolution scanning for immunohistochemistry, one should verify that the protocol works. This can be accomplished using a validation assay where brain sections from the same animal are incubated with primary and secondary antibodies, secondary antibody alone, or neither primary nor secondary antibody. Results for such a validation assay are shown in Figure 2. In this reaction we were detecting the immediate early gene c-Jun in the dorsal h...

Watch this Scientific Journal Video about Using Near-infrared Fluorescence and High-resolution Scanning to Measure Protein Expression in the Rodent Brain at JoVE.com

Using Near-infrared Fluorescence and High-resolution Scanning to Measure Protein Expression in the Rodent Brain

Here, we present a protocol that uses near-infrared dyes in conjunction with immunohistochemistry and high-resolution scanning to assay proteins in brain regions.

Neuroscience is the study of how cells in the brain mediate various functions. Measuring protein expression in neurons and glia is critical for the study ...

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Universidad de Cartagena UDEC

Research

JoVE Journal

Neuroscience

5.4K Views.  University of Delaware. Here, we present a protocol that uses near-infrared dyes in conjunction with immunohistochemistry and high-resolution scanning to assay proteins in brain regions.

Video: Using Near-infrared Fluorescence and High-resolution Scanning to Measure Protein Expression in the Rodent Brain

Simultaneous fMRI and Electrophysiology in the Rodent Brain

To examine the neural basis of the blood oxygenation level dependent (BOLD) magnetic resonance imaging (MRI) signal, we have developed a rodent model in which functional MRI data and in vivo intracortical recording can be performed simultaneously. The combination of MRI and electrical recording is technically challenging because the electrodes used for recording distort the MRI images and the MRI acquisition induces noise in the electrical recording. To minimize the mutual interference of the two modalities, glass microelectrodes were used rather than metal and a noise removal algorithm was implemented for the electrophysiology data. In our studies, two microelectrodes were separately implanted in bilateral primary somatosensory cortices (SI) of the rat and fixed in place. One coronal slice covering the electrode tips was selected for functional MRI. Electrode shafts and fixation positions were not included in the image slice to avoid imaging artifacts. The removed scalp was replaced with toothpaste to reduce susceptibility mismatch and prevent Gibbs ringing artifacts in the images. The artifact structure induced in the electrical recordings by the rapidly-switching magnetic fields during image acquisition was characterized by averaging all cycles of scans for each run. The noise structure during imaging was then subtracted from original recordings. The denoised time courses were then used for further analysis in combination with the fMRI data. As an example, the simultaneous acquisition was used to determine the relationship between spontaneous fMRI BOLD signals and band-limited intracortical electrical activity. Simultaneous fMRI and electrophysiological recording in the rodent will provide a platform for many exciting applications in neuroscience in addition to elucidating the relationship between the fMRI BOLD signal and neuronal activity.

We have developed a method for simultaneous functional magnetic resonance imaging and electrophysiological recording in the rodent brain, providing a platform for the investigation of the relationship between neural activity and the blood oxygenation level dependent (BOLD) MRI signal.

To examine the neural basis of the blood oxygenation level dependent (BOLD) magnetic resonance imaging (MRI) signal, we have developed a rodent model in ...

A Rapid Approach to High-Resolution Fluorescence Imaging in Semi-Thick Brain Slices

A fundamental goal to both basic and clinical neuroscience is to better understand the identities, molecular makeup, and patterns of connectivity that are characteristic to neurons in both normal and diseased brain. Towards this, a great deal of effort has been placed on building high-resolution neuroanatomical maps1-3. With the expansion of molecular genetics and advances in light microscopy has come the ability to query not only neuronal morphologies, but also the molecular and cellular makeup of individual neurons and their associated networks4. Major advances in the ability to mark and manipulate neurons through transgenic and gene targeting technologies in the rodent now allow investigators to 'program' neuronal subsets at will5-6. Arguably, one of the most influential contributions to contemporary neuroscience has been the discovery and cloning of genes encoding fluorescent proteins (FPs) in marine invertebrates7-8, alongside their subsequent engineering to yield an ever-expanding toolbox of vital reporters9. Exploiting cell type-specific promoter activity to drive targeted FP expression in discrete neuronal populations now affords neuroanatomical investigation with genetic precision.
Engineering FP expression in neurons has vastly improved our understanding of brain structure and function. However, imaging individual neurons and their associated networks in deep brain tissues, or in three dimensions, has remained a challenge. Due to high lipid content, nervous tissue is rather opaque and exhibits auto fluorescence. These inherent biophysical properties make it difficult to visualize and image fluorescently labelled neurons at high resolution using standard epifluorescent or confocal microscopy beyond depths of tens of microns. To circumvent this challenge investigators often employ serial thin-section imaging and reconstruction methods10, or 2-photon laser scanning microscopy11. Current drawbacks to these approaches are the associated labor-intensive tissue preparation, or cost-prohibitive instrumentation respectively.
Here, we present a relatively rapid and simple method to visualize fluorescently labelled cells in fixed semi-thick mouse brain slices by optical clearing and imaging. In the attached protocol we describe the methods of: 1) fixing brain tissue in situ via intracardial perfusion, 2) dissection and removal of whole brain, 3) stationary brain embedding in agarose, 4) precision semi-thick slice preparation using new vibratome instrumentation, 5) clearing brain tissue through a glycerol gradient, and 6) mounting on glass slides for light microscopy and z-stack reconstruction (Figure 1).
For preparing brain slices we implemented a relatively new piece of instrumentation called the 'Compresstome' VF-200 (http://www.precisionary.com/products_vf200.html). This instrument is a semi-automated microtome equipped with a motorized advance and blade vibration system with features similar in function to other vibratomes. Unlike other vibratomes, the tissue to be sliced is mounted in an agarose plug within a stainless steel cylinder. The tissue is extruded at desired thicknesses from the cylinder, and cut by the forward advancing vibrating blade. The agarose plug/cylinder system allows for reproducible tissue mounting, alignment, and precision cutting. In our hands, the 'Compresstome' yields high quality tissue slices for electrophysiology, immunohistochemistry, and direct fixed-tissue mounting and imaging. Combined with optical clearing, here we demonstrate the preparation of semi-thick fixed brain slices for high-resolution fluorescent imaging.

Here we describe a rapid and simple method to image fluorescently labeled cells in semi-thick brain slices. By fixing, slicing, and optically clearing brain tissue we describe how standard epifluorescent or confocal imaging can be used to visualize individual cells and neuronal networks within intact nervous tissue.

A fundamental goal to both basic and clinical neuroscience is to better understand the identities, molecular makeup, and patterns of connectivity that are ...

Using MazeSuite and Functional Near Infrared Spectroscopy to Study Learning in Spatial Navigation

MazeSuite is a complete toolset to prepare, present and analyze navigational and spatial experiments1. MazeSuite can be used to design and edit adapted virtual 3D environments, track a participants' behavioral performance within the virtual environment and synchronize with external devices for physiological and neuroimaging measures, including electroencephalogram and eye tracking.
Functional near-infrared spectroscopy (fNIR) is an optical brain imaging technique that enables continuous, noninvasive, and portable monitoring of changes in cerebral blood oxygenation related to human brain functions2-7. Over the last decade fNIR is used to effectively monitor cognitive tasks such as attention, working memory and problem solving7-11. fNIR can be implemented in the form of a wearable and minimally intrusive device; it has the capacity to monitor brain activity in ecologically valid environments. 
Cognitive functions assessed through task performance involve patterns of brain activation of the prefrontal cortex (PFC) that vary from the initial novel task performance, after practice and during retention12. Using positron emission tomography (PET), Van Horn and colleagues found that regional cerebral blood flow was activated in the right frontal lobe during the encoding (i.e., initial na&iuml;ve performance) of spatial navigation of virtual mazes while there was little to no activation of the frontal regions after practice and during retention tests. Furthermore, the effects of contextual interference, a learning phenomenon related to organization of practice, are evident when individuals acquire multiple tasks under different practice schedules13,14. High contextual interference (random practice schedule) is created when the tasks to be learned are presented in a non-sequential, unpredictable order. Low contextual interference (blocked practice schedule) is created when the tasks to be learned are presented in a predictable order.
Our goal here is twofold: first to illustrate the experimental protocol design process and the use of MazeSuite, and second, to demonstrate the setup and deployment of the fNIR brain activity monitoring system using Cognitive Optical Brain Imaging (COBI) Studio software15. To illustrate our goals, a subsample from a study is reported to show the use of both MazeSuite and COBI Studio in a single experiment. The study involves the assessment of cognitive activity of the PFC during the acquisition and learning of computer maze tasks for blocked and random orders. Two right-handed adults (one male, one female) performed 315 acquisition, 30 retention and 20 transfer trials across four days. Design, implementation, data acquisition and analysis phases of the study were explained with the intention to provide a guideline for future studies.

MazeSuite is a complete toolset to prepare, present and analyze navigational and spatial experiments. Functional near-infrared spectroscopy (fNIR) is an optical brain imaging technique that enables noninvasive and portable monitoring of cerebral blood oxygenation changes. This paper summarizes collective use of MazeSuite and fNIR within a cognitive processing learning paradigm.

MazeSuite is a complete toolset to prepare, present and analyze navigational and spatial experiments1. MazeSuite can be used to design and edit adapted ...

High-resolution Live Imaging of Cell Behavior in the Developing Neuroepithelium

The embryonic spinal cord consists of cycling neural progenitor cells that give rise to a large percentage of the neuronal and glial cells of the central nervous system (CNS). Although much is known about the molecular mechanisms that pattern the spinal cord and elicit neuronal differentiation1, 2, we lack a deep understanding of these early events at the level of cell behavior. It is thus critical to study the behavior of neural progenitors in real time as they undergo neurogenesis.
In the past, real-time imaging of early embryonic tissue has been limited by cell/tissue viability in culture as well as the phototoxic effects of fluorescent imaging. Here we present a novel assay for imaging such tissue for long periods of time, utilizing a novel ex vivo slice culture protocol and wide-field fluorescence microscopy (Fig. 1). This approach achieves long-term time-lapse monitoring of chick embryonic spinal cord progenitor cells with high spatial and temporal resolution.
This assay may be modified to image a range of embryonic tissues3, 4 In addition to the observation of cellular and sub-cellular behaviors, the development of novel and highly sensitive reporters for gene activity (for example, Notch signaling5) makes this assay a powerful tool with which to understand how signaling regulates cell behavior during embryonic development.

Imaging embryonic tissue in real-time is challenging over long periods of time. Here we present an assay for monitoring cellular and sub-cellular changes in chick spinal cord for long periods with high spatial and temporal resolution. This technique can be adapted for other regions of the nervous system and developing embryo.

The embryonic spinal cord consists of cycling neural progenitor cells that give rise to a large percentage of the neuronal and glial cells of the central ...

Brain Slice Biotinylation: An Ex Vivo Approach to Measure Region-specific Plasma Membrane Protein Trafficking in Adult Neurons

Regulated endocytic trafficking is the central mechanism facilitating a variety of neuromodulatory events, by dynamically controlling receptor, ion channel, and transporter cell surface presentation on a minutes time scale.&#160;There is a broad diversity of mechanisms that control endocytic trafficking of individual proteins. Studies investigating the molecular underpinnings of trafficking have primarily relied upon surface biotinylation to quantitatively measure changes in membrane protein surface expression in response to exogenous stimuli and gene manipulation.&#160;However, this approach has been mainly limited to cultured cells, which may not faithfully reflect the physiologically relevant mechanisms at play in adult neurons.&#160;Moreover, cultured cell approaches may underestimate region-specific differences in trafficking mechanisms.&#160;Here, we describe an approach that extends cell surface biotinylation to the acute brain slice preparation.&#160;We demonstrate that this method provides a high-fidelity approach to measure rapid changes in membrane protein surface levels in adult neurons.&#160;This approach is likely to have broad utility in the field of neuronal endocytic trafficking.

Brain Slice Biotinylation: An Ex Vivo Approach to Measure Region-specific Plasma Membrane Protein Trafficking in Adult Neurons

Neuronal membrane trafficking dynamically controls plasma membrane protein availability and significantly impacts neurotransmission.&#160;To date, it has been challenging to measure neuronal endocytic trafficking in adult neurons.&#160;Here, we describe a highly effective, quantitative method to measure rapid changes in surface protein expression ex vivo in acute brain slices.

Regulated endocytic trafficking is the central mechanism facilitating a variety of neuromodulatory events, by dynamically controlling receptor, ion ...

Using Fluorescence Activated Cell Sorting to Examine Cell-Type-Specific Gene Expression in Rat Brain Tissue

The brain is comprised of four primary cell types including neurons, astrocytes, microglia and oligodendrocytes. Though they are not the most abundant cell type in the brain, neurons are the most widely studied of these cell types given their direct role in impacting behaviors. Other cell types in the brain also impact neuronal function and behavior via the signaling molecules they produce. Neuroscientists must understand the interactions between the cell types in the brain to better understand how these interactions impact neural function and disease. To date, the most common method of analyzing protein or gene expression utilizes the homogenization of whole tissue samples, usually with blood, and without regard for cell type. This approach is an informative approach for examining general changes in gene or protein expression that may influence neural function and behavior; however, this method of analysis does not lend itself to a greater understanding of cell-type-specific gene expression and the effect of cell-to-cell communication on neural function. Analysis of behavioral epigenetics has been an area of growing focus which examines how modifications of the deoxyribonucleic acid (DNA) structure impact long-term gene expression and behavior; however, this information may only be relevant if analyzed in a cell-type-specific manner given the differential lineage and thus epigenetic markers that may be present on certain genes of individual neural cell types. The Fluorescence Activated Cell Sorting (FACS) technique described below provides a simple and effective way to isolate individual neural cells for the subsequent analysis of gene expression, protein expression, or epigenetic modifications of DNA. This technique can also be modified to isolate more specific neural cell types in the brain for subsequent cell-type-specific analysis.

The goal of this protocol is to use the fluorescence activated cell sorting (FACS) technique to sort specific types of neural cells for subsequent analysis of cell-type-specific gene expression, epigenetic markers, and or protein expression.

The brain is comprised of four primary cell types including neurons, astrocytes, microglia and oligodendrocytes. Though they are not the most abundant ...

Detection of Axonally Localized mRNAs in Brain Sections Using High-Resolution In Situ Hybridization

mRNAs are frequently localized to vertebrate axons and their local translation is required for axon pathfinding or branching during development and for maintenance, repair or neurodegeneration in postdevelopmental periods. High throughput analyses have recently revealed that axons have a more dynamic and complex transcriptome than previously expected. These analysis, however have been mostly done in cultured neurons where axons can be isolated from the somato-dendritic compartments. It is virtually impossible to achieve such isolation in whole tissues in vivo. Thus, in order to verify the recruitment of mRNAs and their functional relevance in a whole animal, transcriptome analyses should ideally be combined with techniques that allow the visualization of mRNAs in situ. Recently, novel ISH technologies that detect RNAs at a single-molecule level have been developed. This is especially important when analyzing the subcellular localization of mRNA, since localized RNAs are typically found at low levels. Here we describe two protocols for the detection of axonally-localized mRNAs using a novel ultrasensitive RNA ISH technology. We have combined RNAscope ISH with axonal counterstain using fluorescence immunohistochemistry or histological dyes to verify the recruitment of Atf4 mRNA to axons in vivo in the mature mouse and human brains.

Detection of Axonally Localized mRNAs in Brain Sections Using High-Resolution In Situ Hybridization

RNA in situ hybridization (ISH) enables the visualization of RNAs in cells and tissues. Here we show how combination of RNAscope ISH with immunohistochemistry or histological dyes can be successfully used to detect mRNAs localized to axons in sections of mouse and human brains.

mRNAs are frequently localized to vertebrate axons and their local translation is required for axon pathfinding or branching during development and for ...

A Simple Way to Measure Alterations in Reward-seeking Behavior Using Drosophila melanogaster

We describe a protocol for measuring ethanol self-administration in fruit flies (Drosophila melanogaster) as a proxy for changes in reward states. We demonstrate a simple way to tap into the fly reward system, modify experiences related to natural reward, and use voluntary ethanol consumption as a measure for changes in reward states. The approach serves as a relevant tool to study the neurons and genes that play a role in experience-mediated changes of internal state. The protocol is composed of two discrete parts: exposing the flies to rewarding and nonrewarding experiences, and assaying voluntary ethanol consumption as a measure of the motivation to obtain a drug reward. The two parts can be used independently to induce the modulation of experience as an initial step for further downstream assays or as an independent two-choice feeding assay, respectively. The protocol does not require a complicated setup and can therefore be applied in any laboratory with basic fly culture tools.

A Simple Way to Measure Alterations in Reward-seeking Behavior Using Drosophila melanogaster

We describe a protocol for inducing rewarding and nonrewarding experiences in fruit flies (Drosophila melanogaster) using voluntary ethanol consumption as a measure for changes in reward states.

We describe a protocol for measuring ethanol self-administration in fruit flies (Drosophila melanogaster) as a proxy for changes in reward states. We ...

Personalized Needles for Microinjections in the Rodent Brain

Microinjections have been used for a long time for the delivery of drugs or toxins within specific brain areas and, more recently, they have been used to deliver gene or cell therapy products. Unfortunately, current microinjection techniques use steel or glass needles that are suboptimal for multiple reasons: in particular, steel needles may cause tissue damage, and glass needles may bend when lowered deeply into the brain, missing the target region. In this article, we describe a protocol to prepare and use quartz needles that combine a number of useful features. These needles do not produce detectable tissue damage and, being very rigid, ensure reliable delivery in the desired brain region even when using deep coordinates. Moreover, it is possible to personalize the design of the needle by making multiple holes of the desired diameter. Multiple holes facilitate the injection of large amounts of solution within a larger area, whereas large holes facilitate the injection of cells. In addition, these quartz needles can be cleaned and re-used, such that the procedure becomes cost-effective.

We describe here a protocol for microinjection in the rodent brain that uses quartz needles. These needles do not produce detectable tissue damage and ensure reliable delivery even in deep regions. Moreover, they can be adapted to research needs by personalized designs and can be re-used.

Microinjections have been used for a long time for the delivery of drugs or toxins within specific brain areas and, more recently, they have been used to ...

Conducting Hyperscanning Experiments with Functional Near-Infrared Spectroscopy

Concurrent brain recordings of two or more interacting persons, an approach termed hyperscanning, are gaining increasing importance for our understanding of the neurobiological underpinnings of social interactions, and possibly interpersonal relationships. Functional near-infrared spectroscopy (fNIRS) is well suited for conducting hyperscanning experiments because it measures local hemodynamic effects with a high sampling rate and, importantly, it can be applied in natural settings, not requiring strict motion restrictions. In this article, we present a protocol for conducting fNIRS hyperscanning experiments with parent-child dyads and for analyzing brain-to-brain synchrony. Furthermore, we discuss critical issues and future directions, regarding the experimental design, spatial registration of the fNIRS channels, physiological influences and data analysis methods. The described protocol is not specific to parent-child dyads, but can be applied to a variety of different dyadic constellations, such as adult strangers, romantic partners or siblings. To conclude, fNIRS hyperscanning has the potential to yield new insights into the dynamics of the ongoing social interaction, which possibly go beyond what can be studied by examining the activities of individual brains.

The present protocol describes how to conduct fNIRS hyperscanning experiments and analyze brain-to-brain synchrony. Further, we discuss challenges and possible solutions.

Concurrent brain recordings of two or more interacting persons, an approach termed hyperscanning, are gaining increasing importance for our understanding ...

Using Near-infrared Fluorescence and High-resolution Scanning to Measure Protein Expression in the Rodent Brain

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Brain Slice Biotinylation: An Ex Vivo Approach to Measure Region-specific Plasma Membrane Protein Trafficking in Adult Neurons

Using Fluorescence Activated Cell Sorting to Examine Cell-Type-Specific Gene Expression in Rat Brain Tissue

Detection of Axonally Localized mRNAs in Brain Sections Using High-Resolution In Situ Hybridization

A Simple Way to Measure Alterations in Reward-seeking Behavior Using Drosophila melanogaster

Personalized Needles for Microinjections in the Rodent Brain

Conducting Hyperscanning Experiments with Functional Near-Infrared Spectroscopy