This work was funded by NINDS and American Heart Association to S.Ge. This approach was originally established and developed by the author in Dr. Hongjun Song's laboratory in the Johns Hopkins University. We would like to thank Dr. Hongjun Song for his guidance and support.

1. Virus Injection
High-titer engineered retrovirus (1&times;109 unit/ml) is produced by co-transfection of retroviral vectors and VSVG into HEK293T cells, followed by ultracentrifugation of viral supernatant. For sources and production methods, see the excellent JoVE demonstration (3).
Note: Young adult (4-6 weeks old) female C57Bl/6 mice (Charles River) are housed under standard conditions. All procedures follow the National Research Council's Guide for the care and use of laboratory animals under a protocol approved by the Stony Brook University IACUC.
<ol>
	<li>Thaw 2ul of frozen retrovirus per animal on ice.</li>
	<li>Anaesthetize (100 &mu;g ketamine + 10 &mu;g xylazine per gram body weight) and mount the animal on a stereotaxic frame (Steolting). Remove the hair on the head and wipe the skin with 70% ethanol.</li>
	<li>Expose the skull and drill four shallow holes using a dental drill (0.6mm drill bit) at the following coordinates:
		<ul>
 	<li>anterioposterior = -2 mm from bregma; lateral = &plusmn;1.6 mm; ventral = 2.5 mm; anterioposterior = -3 mm from bregma; lateral = &plusmn;2.6 mm; ventral = 3.2 mm.</li>
 <li>anterioposterior = -2 mm from bregma; lateral = &plusmn;1.6 mm; ventral = 2.5 mm; anterioposterior = -3 mm from bregma; lateral = &plusmn;2.6 mm; ventral = 3.2 mm.</li>
		</ul>
		</li>
	<li>Mount a 1&mu;l Hamilton, flat-tip syringe and inject 0.5 &mu;l retrovirus per site at a rate of 0.25 &mu;l/min into the dentate gyrus. (See the above coordinates for ventral depth.) Pause 2 minutes after each injection before slowly withdrawing the syringe to prevent fluid backflow. Between injections, briefly rinse the external surface of the syringe tip with sterile PBS and an applicator to remove traces of blood.</li>
		<li>Close the wound with sterile surgical suture material (Type P-1; Size 6-0) and return the animal to standard housing conditions until the desired time stages after injection.</li>
	</ol>
2. Slice Preparation
To obtain high-quality acute slices from adult mice, we use a modified cutting solution for slice preparation (see below).
<ol>
	<li>Pre-chill cutting solution to 0-4 &deg;C on ice and bubble with 95% O2-5% CO2 for at least 30 minutes.</li>
	<li>Anaesthetize and transcardially perfuse an animal with ice-cold oxygen-saturated cutting solution.</li>
	<li>Quickly remove the brain into a petri-dish with filter-paper pre-wetted with cold, oxygenated cutting solution. Cut off the cerebellum and slice a mounting surface at least 1mm anterior to the (visible) injection coordinates. Glue the brain -onto a vibrotome stage and mount it into the cutting chamber filled with cold and oxygenated cutting solution.</li>
	<li>Prepare coronal or horizontal slices (300-350&mu;m) and transfer them with a large-bore pipette to an incubating chamber containing room-temperature ACSF bubbled with 95% O2/5% CO2.</li>
	<li>Incubate the slices, bubbling continuously, at 32&deg;C for 30-60 minutes. Return the chamber to room temperature for the duration of the recording.</li>
</ol>
3. Electrophysiological Experiments
<ol>
	<li>Slices are transferred into the recording chamber which is continuously perfused with oxygen-saturated ACSF at 32&deg;C - 34&deg;C.</li>
	<li>A bipolar tungsten stimulation electrode is placed in the molecular layer of the dentate gyrus using a low magnification microscope objective (10X).</li>
	<li>Newborn DGCs in the sub-granular zone/ granular cell layer are identified by the expression of GFP or dTomato. Whole-cell patchclamp recording is performed on newborn neurons under high magnification (40X).</li>
	<li>Firing properties of the recorded cells are obtained by injection of a series of currents under current-clamp mode.</li>
	<li>Electric stimuli are delivered by the stimulation electrode via a stimulation isolator controlled by the recording software, and evoked postsynaptic currents in the newborn DGCs are recorded.</li>
</ol>
4. Data Analysis
Amplitudes of evoked postsynaptic responses are analyzed at different developmental stages of adult-born neurons.
5. Representative Results
Using the above protocol, GFP expression in newborn dentate gyrus neurons similar to Figure 1 is common. Note that newborn neurons are easily visualized and both dendrites and axons are robustly labeled. Expression in thin DGC axons and small spines depends on the quality and titer of the virus, the promoter used and the length of in vivo expression. In our hands, newborn cells and sub-cellular organelles are usually visible within a few days following injection, and spine expression can be traced from the earliest stages of development. Whole-cell recordings from newborn neurons at different time stages allow the study of unique newborn cell properties, e.g. action potentials (Figure 2a), as well as the process of synaptic integration into existing neural circuits during maturation (Figure 2b).
<img src="/files/ftp_upload/2548/2548fig1.jpg" alt="Figure 1" /> Figure 1 2-photon confocal image of newborn neurons in a horizontal dentate gyrus section of an adult mouse. Green cells are 21dpi (days post injection) GFP-expressing newborn DGCs labeled with pUX-GFP retrovirus.
<img src="/files/ftp_upload/2548/2548fig2.jpg" alt="Figure 2" /> Figure 2 a) Action potential firing properties of a newborn DGC at 21 dpi. b) representative evoked excitatory postsynaptic currents (EPSCs) recorded on a newborn DGC at 21 dpi.

<ol>
	<li>Zhao, C., Deng, W., Gage, F. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+and+functional+implications+of+adult+neurogenesis.">Mechanisms and functional implications of adult neurogenesis.</a> Cell. 132, 645-660 (2008).</li><li>Ge, S., Goh, E. L., Sailor, K. A., Kitabatake, Y., Ming, G. L., Song, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=GABA+regulates+synaptic+integration+of+newly+generated+neurons+in+the+adult+brain.">GABA regulates synaptic integration of newly generated neurons in the adult brain.</a> Nature. 439, 589-593 (2006).</li><li>Gavrilescu, L. C., Van Etten, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+of+replication-defective+retrovirus+by+transient+transfection+of+293T+cells.">Production of replication-defective retrovirus by transient transfection of 293T cells.</a> J Vis Exp. , (2007).</li></ol>

No conflicts of interest declared.

Continuous neurogenesis in the hippocampus of adult mammalian brains provides a unique experimental model system to study neuronal development and integration in the mature brain. The protocol presented here combines retroviral labeling and electrophysiological methods to study the integration of newborn dentate granule neurons in the brains of adult mice.
To ensure that your experiments are successful, we recommend the following during critical steps of the procedure:
To avoid unwanted infection and inflammation, all tools should be sterilized (by autoclaving, any type of sterilizer, or 70% ethanol) before surgery. Use sterile PBS to wash the tip of the syringe needle before injection.
For virus injection, animals must to be well mounted on the stereotaxic device and sources of unnecessary movement must be minimized during injection. Make sure the head is well fixed and firm, and adjust the nose position of the mouse to level bregma and lambda prior to calculating injection coordinates. Extract virus into the syringe quickly to minimize exposure to room temperatures - retroviruses are particularly temperature sensitive. Inject virus slowly at the recommended rate to minimize pressure damage. Using the recommended flat-tipped syringe (vs. common beveled tip)&nbsp;will ensure an evenly distributed dentate gyrus infection area.
Before preparing slices, cutting solution and incubating ACSF must be bubbled with 95% O2-5% CO2 for at least 30 minutes to allow oxygen to saturate the solutions. Animals should be perfused quickly and tissue maintained in cold, oxygen-saturated solution for best slice quality.
For recording, increase the stimulus intensity gradually until there is a postsynaptic response. Change location of the stimulation electrode within the molecular layer of dentate gyrus as necessary.
In summary, the recommended approach offers a way to explore distinct properties and possible functional roles of adult-born neurons during early-stage integration into active, mature circuitry.

<ul>
	<li>Cutting solution (in mM): 110 choline chloride, 2.5 KCl, 1.3 KH2PO4, 25.0 NaHCO3, 0.5 CaCl2, 7 MgCl2, 10 dextrose, 1.3 sodium ascorbate, 0.6 sodium pyruvate, 5.0 kynurenic acid.&nbsp;</li>
	<li>Artificial cerebro-spinal fluid (ACSF, in mM): 125.0 NaCl, 25.0 NaHCO3, 2.5 KCl, 2 CaCl2, 1.3 KH2PO4, 1.3 MgCl2, 1.3 sodium ascorbate, 0.6 sodium pyruvate, 10 dextrose. </li>
	<li>Internal solution for whole-cell patchclamp (in mM): 120 potassium gluconate, 15 KCl, 4 MgCl2, 0.1 EGTA, 10.0 HEPES, 4 MgATP, 0.3 Na3GTP, 7 phosphocreatine (pH 7.4, 300 mOsm).</li>
</ul>

studying the integration of adult-born neurons

Neurogenesis occurs in adult mammalian brains in the sub-ventricular zone (SVZ) of the lateral ventricle and in the sub-granular zone (SGZ) of the hippocampal dentate gyrus throughout life. Previous reports have shown that adult hippocampal neurogenesis is associated with diverse brain disorders, including epilepsy, schizophrenia, depression and anxiety (1). Deciphering the process of normal and aberrant adult-born neuron integration may shed light on the etiology of these diseases and inform the development of new therapies.
SGZ adult neurogenesis mirrors embryonic and post-natal neuronal development, including stages of fate specification, migration, synaptic integration, and maturation. However, full integration occurs over a prolonged, 6-week period. Initial synaptic input to adult-born SGZ dentate granule cells (DGCs) is GABAergic, followed by glutamatergic input at 14 days (2). The specific factors which regulate circuit formation of adult-born neurons in the dentate gyrus are currently unknown.
Our laboratory uses a replication-deficient retroviral vector based on the Moloney murine leukemia virus to deliver fluorescent proteins and hypothesized regulatory genes to these proliferating cells. This viral technique provides high specificity and resolution for analysis of cell birth date, lineage, morphology, and synaptogenesis.
A typical experiment often employs two or three viruses containing unique label, transgene, and promoter elements for single-cell analysis of a desired developmental process in vivo. The following protocol describes a method for analyzing functional newborn neuron integration using a single green (GFP) or red (dTomato) fluorescent protein retrovirus and patch-clamp electrophysiology.

Watch this Scientific Journal Video about Studying the Integration of Adult-born Neurons at JoVE.com

Studying the Integration of Adult-born Neurons

A way to study the integration of newborn dentate granule cells in adult animals is described. This technique uses an engineered retrovirus to label newborn neurons, followed by electrophysiological recordings to determine in vivo functional integration.

Neurogenesis occurs in adult mammalian brains in the sub-ventricular zone (SVZ) of the lateral ventricle and in the sub-granular zone (SGZ) of the ...

studying-the-integration-of-adult-born-neurons

Research

JoVE Journal

Neuroscience

13.8K Views.  State University of New York at Stony Brook. A way to study the integration of newborn dentate granule cells in adult animals is described. This technique uses an engineered retrovirus to label newborn neurons, followed by electrophysiological recordings to determine in vivo functional integration.

Video: Studying the Integration of Adult-born Neurons

In utero Electroporation followed by Primary Neuronal Culture for Studying Gene Function in Subset of Cortical Neurons

In vitro study of primary neuronal cultures allows for quantitative analyses of neurite outgrowth. In order to study how genetic alterations affect neuronal process outgrowth, shRNA or cDNA constructs can be introduced into primary neurons via chemical transfection or viral transduction. However, with primary cortical cells, a heterogeneous pool of cell types (glutamatergic neurons from different layers, inhibitory neurons, glial cells) are transfected using these methods. The use of in utero electroporation to introduce DNA constructs in the embryonic rodent cortex allows for certain subsets of cells to be targeted: while electroporation of early embryonic cortex targets deep layers of the cortex, electroporation at late embryonic timepoints targets more superficial layers. Further, differential placement of electrodes across the heads of individual embryos results in the targeting of dorsal-medial versus ventral-lateral regions of the cortex. Following electroporation, transfected cells can be dissected out, dissociated, and plated in vitro for quantitative analysis of neurite outgrowth. Here, we provide a step-by-step method to quantitatively measure neuronal process outgrowth in subsets of cortical cells.
The basic protocol for in utero electroporation has been described in detail in two other JoVE articles from the Kriegstein lab 1, 2. We will provide an overview of our protocol for in utero electroporation, focusing on the most important details, followed by a description of our protocol that applies in utero electroporation to the study of gene function in neuronal process outgrowth.

In utero Electroporation followed by Primary Neuronal Culture for Studying Gene Function in Subset of Cortical Neurons

In utero electroporation is a valuable method for transfecting neuronal progenitor cells in vivo. Depending upon the placement of the electrodes and the developmental timepoint of electroporation, certain subsets of cortical cells can be targeted. Targeted cells can then be analyzed in vivo or in vitro for effects of genetic alteration.

In vitro study of primary neuronal cultures allows for quantitative analyses of neurite outgrowth. In order to study how genetic alterations affect ...

Studying the Neural Basis of Adaptive Locomotor Behavior in Insects

Studying the neural basis of walking behavior, one often faces the problem that it is hard to separate the neuronally produced stepping output from those leg movements that result from passive forces and interactions with other legs through the common contact with the substrate. If we want to understand, which part of a given movement is produced by nervous system motor output, kinematic analysis of stepping movements, therefore, needs to be complemented with electrophysiological recordings of motor activity. The recording of neuronal or muscular activity in a behaving animal is often limited by the electrophysiological equipment which can constrain the animal in its ability to move with as many degrees of freedom as possible. This can either be avoided by using implantable electrodes and then having the animal move on a long tether (i.e. Clarac et al., 1987; Duch &amp; Pfl&uuml;ger, 1995; B&ouml;hm et al., 1997; Gruhn &amp; Rathmayer, 2002) or by transmitting the data using telemetric devices (Kutsch et al, 1993; Fischer et al., 1996; Tsuchida et al. 2004; Hama et al., 2007; Wang et al., 2008). Both of these elegant methods, which are successfully used in larger arthropods, often prove difficult to apply in smaller walking insects which either easily get entangled in the long tether or are hindered by the weight of the telemetric device and its batteries. In addition, in all these cases, it is still impossible to distinguish between the purely neuronal basis of locomotion and the effects exerted by mechanical coupling between the walking legs through the substrate. One solution for this problem is to conduct the experiments in a tethered animal that is free to walk in place and that is locally suspended, for example over a slippery surface, which effectively removes most ground contact mechanics. This has been used to study escape responses (Camhi and Nolen, 1981; Camhi and Levy, 1988), turning (Tryba and Ritzman, 2000a,b; Gruhn et al., 2009a), backward walking (Graham and Epstein, 1985) or changes in velocity (Gruhn et al., 2009b) and it allows the experimenter easily to combine intra- and extracellular physiology with kinematic analyses (Gruhn et al., 2006).
We use a slippery surface setup to investigate the timing of leg muscles in the behaving stick insect with respect to touch-down and lift-off under different behavioral paradigms such as straight forward and curved walking in intact and reduced preparations.

We describe a method to record motor activity, timed to the electrically recorded tarsal contact signal in a tethered insect, walking on a slippery surface. This is used to study the neural basis of adaptive behavior under reduced influence of mechanical interaction between legs through the substrate.

Studying the neural basis of walking behavior, one often faces the problem that it is hard to separate the neuronally produced stepping output from those ...

Selective Viral Transduction of Adult-born Olfactory Neurons for Chronic in vivo Optogenetic Stimulation

Local interneurons are continuously regenerated in the olfactory bulb of adult rodents1-3. In this process, called adult neurogenesis, neural stem cells in the walls of the lateral ventricle give rise to neuroblasts that migrate for several millimeters along the rostral migratory stream (RMS) to reach and incorporate into the olfactory bulb. To study the different steps and the impact of adult-born neuron integration into preexisting olfactory circuits, it is necessary to selectively label and manipulate the activity of this specific population of neurons. The recent development of optogenetic technologies offers the opportunity to use light to precisely activate this specific cohort of neurons without affecting surrounding neurons4,5. Here, we present a series of procedures to virally express Channelrhodopsin2(ChR2)-YFP in a temporally restricted cohort of neuroblasts in the RMS before they reach the olfactory bulb and become adult-born neurons. In addition, we show how to implant and calibrate a miniature LED for chronic in vivo stimulation of ChR2-expressing neurons.

Selective Viral Transduction of Adult-born Olfactory Neurons for Chronic in vivo Optogenetic Stimulation

Adult-born neurons of the olfactory bulb can be optogenetically controlled using Channelrhodopsin2-expressing lentiviral injection in the rostral migratory stream and chronic photostimulation with an implanted miniature LED.

Local interneurons are continuously regenerated in the olfactory bulb of adult rodents1-3. In this process, called adult neurogenesis, neural stem cells ...

The Specification of Telencephalic Glutamatergic Neurons from Human Pluripotent Stem Cells

Here, a stepwise procedure for efficiently generating telencephalic glutamatergic neurons from human pluripotent stem cells (PSCs) has been described. The differentiation process is initiated by breaking the human PSCs into clumps which round up to form aggregates when the cells are placed in a suspension culture. The aggregates are then grown in hESC medium from days 1-4 to allow for spontaneous differentiation. During this time, the cells have the capacity to become any of the three germ layers. From days 5-8, the cells are placed in a neural induction medium to push them into the neural lineage. Around day 8, the cells are allowed to attach onto 6 well plates and differentiate during which time the neuroepithelial cells form. These neuroepithelial cells can be isolated at day 17. The cells can then be kept as neurospheres until they are ready to be plated onto coverslips. Using a basic medium without any caudalizing factors, neuroepithelial cells are specified into telencephalic precursors, which can then be further differentiated into dorsal telencephalic progenitors and glutamatergic neurons efficiently. Overall, our system provides a tool to generate human glutamatergic neurons for researchers to study the development of these neurons and the diseases which affect them.

This procedure yields telencephalic neurons by going through checkpoints which are similar to those observed during human development. The cells are allowed to spontaneously differentiate, are exposed to factors which push them towards the neural lineage, are isolated, and are plated onto coverslips to allow for terminal differentiation and maturation.

Here, a stepwise procedure for efficiently generating telencephalic glutamatergic neurons from human pluripotent stem cells (PSCs) has been described. The ...

Fast Micro-iontophoresis of Glutamate and GABA: A Useful Tool to Investigate Synaptic Integration

One of the fundamental interests in neuroscience is to understand the integration of excitatory and inhibitory inputs along the very complex structure of the dendritic tree, which eventually leads to neuronal output of action potentials at the axon. The influence of diverse spatial and temporal parameters of specific synaptic input on neuronal output is currently under investigation, e.g. the distance-dependent attenuation of dendritic inputs, the location-dependent interaction of spatially segregated inputs, the influence of GABAergig inhibition on excitatory integration, linear and non-linear integration modes, and many more.
With fast micro-iontophoresis of glutamate and GABA it is possible to precisely investigate the spatial and temporal integration of glutamatergic excitation and GABAergic inhibition. Critical technical requirements are either a triggered fluorescent lamp, light-emitting diode (LED), or a two-photon scanning microscope to visualize dendritic branches without introducing significant photo-damage of the tissue. Furthermore, it is very important to have a micro-iontophoresis amplifier that allows for fast capacitance compensation of high resistance pipettes. Another crucial point is that no transmitter is involuntarily released by the pipette during the experiment.
Once established, this technique will give reliable and reproducible signals with a high neurotransmitter and location specificity. Compared to glutamate and GABA uncaging, fast iontophoresis allows using both transmitters at the same time but at very distant locations without limitation to the field of view. There are also advantages compared to focal electrical stimulation of axons: with micro-iontophoresis the location of the input site is definitely known and it is sure that only the neurotransmitter of interest is released. However it has to be considered that with micro-iontophoresis only the postsynapse is activated and presynaptic aspects of neurotransmitter release are not resolved. In this article we demonstrate how to set up micro-iontophoresis in brain slice experiments.

In this article we introduce fast micro-iontophoresis of neurotransmitters as a technique to investigate integration of postsynaptic signals with high spatial and temporal precision.

One of the fundamental interests in neuroscience is to understand the integration of excitatory and inhibitory inputs along the very complex structure of ...

Methods for Studying the Mechanisms of Action of Antipsychotic Drugs in Caenorhabditis elegans

Caenorhabditis elegans is a simple genetic organism amenable to large-scale forward and reverse genetic screens and chemical genetic screens. The C. elegans genome includes potential antipsychotic drug (APD) targets conserved in humans, including genes encoding proteins required for neurotransmitter synthesis and for synaptic structure and function. APD exposure produces developmental delay and/or lethality in nematodes in a concentration-dependent manner. These phenotypes are caused, in part, by APD-induced inhibition of pharyngeal pumping1,2. Thus, the developmental phenotype has a neuromuscular basis, making it useful for pharmacogenetic studies of neuroleptics. Here we demonstrate detailed procedures for testing APD effects on nematode development and pharyngeal pumping. For the developmental assay, synchronized embryos are placed on nematode growth medium (NGM) plates containing APDs, and the stages of developing animals are then scored daily. For the pharyngeal pumping rate assay, staged young adult animals are tested on NGM plates containing APDs. The number of pharyngeal pumps per unit time is recorded, and the pumping rate is calculated. These assays can be used for studying many other types of small molecules or even large molecules.

Methods for Studying the Mechanisms of Action of Antipsychotic Drugs in Caenorhabditis elegans

Approaches for testing the effects of antipsychotic drugs (APDs) in Caenorhabditis elegans are demonstrated. Assays are described for testing drug effects on development and viability and on pharyngeal pumping rate. These methods are also applicable for pharmacogenetic experiments with drug classes other than APDs.

Caenorhabditis elegans is a simple genetic organism amenable to  large-scale forward and reverse genetic screens and chemical genetic screens. The C.  ...

Differential Labeling of Cell-surface and Internalized Proteins after Antibody Feeding of Live Cultured Neurons

In order to demonstrate the cell-surface localization of a putative transmembrane receptor in cultured neurons, we labeled the protein on the surface of live neurons with a specific primary antibody raised against an extracellular portion of the protein. Given that receptors are trafficked to and from the surface, if cells are permeabilized after fixation then both cell-surface and internal protein will be detected by the same labeled secondary antibody. Here, we adapted a method used to study protein trafficking (&#8220;antibody feeding&#8221;) to differentially label protein that had been internalized by endocytosis during the antibody incubation step and protein that either remained on the cell surface or was trafficked to the surface during this period. The ability to distinguish these two pools of protein was made possible through the incorporation of an overnight blocking step with highly-concentrated unlabeled secondary antibody after an initial incubation of unpermeabilized neurons with a fluorescently-labeled secondary antibody. After the blocking step, permeabilization of the neurons allowed detection of the internalized pool with a fluorescent secondary antibody labeled with a different fluorophore. Using this technique we were able to obtain important information about the subcellular location of this putative receptor, revealing that it was, indeed, trafficked to the cell-surface in neurons. This technique is broadly applicable to a range of cell types and cell-surface proteins, providing a suitable antibody to an extracellular epitope is available.

We describe a method to label protein on the surface of living neurons using a specific polyclonal antibody to extracellular epitopes. Protein bound by the antibody on the cell surface and subsequently internalized via endocytosis can be distinguished from protein remaining on, or trafficked to, the surface during the incubation.

In order to demonstrate the cell-surface localization of a putative transmembrane receptor in cultured neurons, we labeled the protein on the surface of ...

A Microbiomechanical System for Studying Varicosity Formation and Recovery in Central Neuron Axons

Axonal varicosities are enlarged structures along the shafts of axons with a high degree of heterogeneity. They are present not only in brains with neurodegenerative diseases or injuries, but also in the normal brain. Here, we describe a newly-established micromechanical system to rapidly, reliably, and reversibly induce axonal varicosities, allowing us to understand the mechanisms governing varicosity formation and heterogeneous protein composition. This system represents a novel means to evaluate the effects of compression and shear stress on different subcellular compartments of neurons, different from other in vitro systems that mainly focus on the effect of stretching. Importantly, owing to the unique features of our system, we recently made a novel discovery showing that the application of pressurized fluid can rapidly and reversibly induce axonal varicosities through the activation of a transient receptor potential channel. Our biomechanical system can be utilized conveniently in combination with drug perfusion, live cell imaging, calcium imaging, and patch clamp recording. Therefore, this method can be adopted for studying mechanosensitive ion channels, axonal transport regulation, axonal cytoskeleton dynamics, calcium signaling, and morphological changes related to traumatic brain injury.

This protocol describes a physiologically relevant, pressurized fluid approach for rapid and reversible induction of varicosities in neurons.

Axonal varicosities are enlarged structures along the shafts of axons with a high degree of heterogeneity. They are present not only in brains with ...

An In Vitro Model for Studying Tau Aggregation Using Lentiviral-mediated Transduction of Human Neurons

Aberrant aggregation of the protein tau is pathogenically involved in a number of neurodegenerative diseases, including Alzheimer&#8217;s disease (AD). Although mouse models of tauopathy have provided a valuable resource for investigating the neurotoxic mechanisms of aggregated tau, it is becoming increasingly apparent that, due to interspecies differences in neurophysiology, the mouse brain is unsuitable for modeling the human condition. Advances in cell culture methods have made human neuronal cultures accessible for experimental use in vitro and have aided in the development of neurotherapeutics. However, despite the adaptation of human neuronal cell cultures, in vitro models of human tauopathy are not yet widely available. This protocol describes a cellular model of tau aggregation in which human neurons are transduced with lentiviral-derived vectors that code for pathogenically mutated tau fused to a yellow fluorescent protein (YFP) reporter. Transduced cultures produce tau aggregates that stain positively for thioflavin and display markers of neurotoxicity, such as decreased axonal length and increased lysosomal volume. This procedure may be a useful and cost-effective model for studying human tauopathies.

This protocol details a procedure in which human neuronal cultures are transduced with lentiviral constructs coding for mutant human tau. Transduced cultures display tau aggregates and associated pathologies.

Aberrant aggregation of the protein tau is pathogenically involved in a number of neurodegenerative diseases, including Alzheimer&#8217;s disease (AD). ...

Wireless Electrophysiological Recording of Neurons by Movable Tetrodes in Freely Swimming Fish

The neural mechanisms governing fish behavior remain mostly unknown, although fish constitute the majority of all vertebrates. The ability to record brain activity from freely moving fish would advance research on the neural basis of fish behavior considerably. Moreover, precise control of the recording location in the brain is critical to studying coordinated neural activity across regions in fish brain. Here, we present a technique that records wirelessly from the brain of freely swimming fish while controlling for the depth of the recording location. The system is based on a neural logger associated with a novel water-compatible implant that can adjust the recording location by microdrive-controlled tetrodes. The capabilities of the system are illustrated through recordings from the telencephalon of goldfish.

A novel wireless technique for recording extracellular neural signals from the brain of freely swimming goldfish is presented. The recording device is composed of two tetrodes, a microdrive, a neural data logger, and a waterproof case. All parts are custom-made except for the data logger and its connector.

The neural mechanisms governing fish behavior remain mostly unknown, although fish constitute the majority of all vertebrates. The ability to record brain ...