Name: a microbiomechanical system for studying varicosity formation and recovery in central neuron axons
Uploaded: 2018-04-30T13:00:00
Description: Watch this Scientific Journal Video about A Microbiomechanical System for Studying Varicosity Formation and Recovery in Central Neuron Axons at JoVE.com

All animal experiments have been conducted in accordance with the National Institutes of Health Animal Use Guidelines. This work was supported in part by grants from National Institutes of Health (R01NS093073 and R21AA024873) to C. Gu.

All methods described below have been approved by the Institutional Animal Care and Use Committee (IACUC) of the Ohio State University.
1. Coverslip Preparation
<ol>
	<li>Place one or more boxes of 12 mm or 25 mm coverslips into a glass beaker containing 70% nitric acid and incubate the coverslips at room temperature overnight. 
	NOTE: Do not wash the 25 mm coverslips in the same beaker as the 12 mm coverslips. It is better to wash them separately.</li>
	<li>Transfer all coverslips into...

<ol>
	<li>Niki&#263;, I., 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+reversible+form+of+axon+damage+in+experimental+autoimmune+encephalomyelitis+and+multiple+sclerosis.">A reversible form of axon damage in experimental autoimmune encephalomyelitis and multiple sclerosis.</a> Nat. Med. 17, 495-499 (2011).</li><li>Yang, 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=Regulation+of+axon+degeneration+after+injury+and+in+development+by+the+endogenous+calpain+inhibitor+calpastatin.">Regulation of axon degeneration after injury and in development by the endogenous calpain inhibitor calpastatin.</a> Neuron. 80 (5), 1175-1189 (2013).</li><li>Debanne, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Information+processing+in+the+axon.">Information processing in the axon.</a> Nat. Rev. Neurosci. 5, 304-316 (2004).</li><li>Gu, Y., Jukkola, P., Wang, Q., Esparza, T., Zhao, Y., Brody, D., Gu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polarity+of+varicosity+initiation+in+central+neuron+mechanosensation.">Polarity of varicosity initiation in central neuron mechanosensation.</a> J Cell Biol. 216 (7), 2179-2199 (2017).</li><li>Chung, R. 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=Mild+axonal+stretch+injury+in+vitro+induces+a+progressive+series+of+neurofilament+alterations+ultimately+leading+to+delayed+axotomy.">Mild axonal stretch injury in vitro induces a progressive series of neurofilament alterations ultimately leading to delayed axotomy.</a> J. Neurotrauma. 22 (10), 1081-1091 (2005).</li><li>Staal, J. A., Dickson, T. C., Chung, R. S., Vickers, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cyclosporin-A+treatment+attenuates+delayed+cytoskeletal+alterations+and+secondary+axotomy+following+mild+axonal+stretch+injury.">Cyclosporin-A treatment attenuates delayed cytoskeletal alterations and secondary axotomy following mild axonal stretch injury.</a> Dev. Neurobiol. 67 (14), 1831-1842 (2007).</li><li>Tang-Schomer, M. D., Johnson, V. E., Baas, P. W., Stewart, W., Smith, D. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Partial+interruption+of+axonal+transport+due+to+microtubule+breakage+accounts+for+the+formation+of+periodic+varicosities+after+traumatic+axonal+injury.">Partial interruption of axonal transport due to microtubule breakage accounts for the formation of periodic varicosities after traumatic axonal injury.</a> Exp. Neurol. 233 (1), 364-372 (2012).</li><li>Donkin, J. J., Vink, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+of+cerebral+edema+in+traumatic+brain+injury:+therapeutic+developments.">Mechanisms of cerebral edema in traumatic brain injury: therapeutic developments.</a> Curr Opin Neurol. 23 (3), 293-299 (2010).</li><li>Gardner, A., Jukkola, P., Gu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myelination+of+rodent+hippocampal+neurons+in+culture.">Myelination of rodent hippocampal neurons in culture.</a> Nat Protoc. 7 (10), 1774-1782 (2012).</li><li>Wang, Q., Zhang, X., Zhao, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Micromechanical+stimulator+for+localized+cell+loading:+fabrication+and+strain+analysis.">Micromechanical stimulator for localized cell loading: fabrication and strain analysis.</a> J. Micromech. Microeng. 23, 015002 (2013).</li><li>Lu, Y. B., 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=Viscoelastic+properties+of+individual+glial+cells+and+neurons+in+the+CNS.">Viscoelastic properties of individual glial cells and neurons in the CNS.</a> Proc. Natl. Acad. Sci. USA. 103 (47), 17759-17764 (2006).</li><li>Elkin, B. S., Azeloglu, E. U., Costa, K. D., Morrison, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+heterogeneity+of+the+rat+hippocampus+measured+by+atomic+force+microscope+indentation.">Mechanical heterogeneity of the rat hippocampus measured by atomic force microscope indentation.</a> J. Neurotrauma. 24 (5), 812-822 (2007).</li><li>Franze, 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=Neurite+branch+retraction+is+caused+by+a+threshold-dependent+mechanical+impact.">Neurite branch retraction is caused by a threshold-dependent mechanical impact.</a> Biophys. J. 97 (7), 1883-1890 (2009).</li><li>Camp&#224;s, O., 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=Quantifying+cell-generated+mechanical+forces+within+living+embryonic+tissues.">Quantifying cell-generated mechanical forces within living embryonic tissues.</a> Nat. Methods. 11 (2), 183-189 (2014).</li></ol>

The procedure of this microbiomechanical assay is straight forward. It will produce reliable results, if all its steps are carefully carried out. There are several key steps that, if improperly performed, will hinder successful data collection. The critical steps begin upstream of the actual application of the puffing stimulus. Careful dissection, culturing, and care of the primary neuron culture are paramount. If the cultured neurons are not healthy, they will not react consistently, since they might have already been p...

Varicosity formation, or swelling/beading, along axons, is a prominent feature of neurodegeneration observed in many disorders or injuries of the central nervous system, including multiple sclerosis, Alzheimer&#39;s disease, Parkinson&#39;s disease, and traumatic brain injury1,2. Despite the significant physiological impacts of axonal varicosities on action potential propagation and synaptic transmission3, how the varicosities are generated remains unknown. Recently, using a newly-established microbiomechanical assay on cultured hippocampal neurons from rodents, we found that mechanical stimuli can induce varicosities in these neurons with highly intriguing features. First, varicosity induction is rapid (&#60;10 s) and this process is unexpectedly reversible. Second, varicosity initiation depends on the strength of puffing pressure: the higher the pressure, the faster the initiation. Third, varicosity initiation depends on neuronal age. The axons of younger neurons appear more responsive to mechanical stress, compared to those of older neurons. Fourth, the varicosities form along the axons of hippocampal neurons, while the dendrites and initial axon segments of these neurons display no change under the same puffing condition. Thus, our study revealed a novel feature of neuronal polarity. These findings with the in vitro system are physiologically relevant. Using an in vivo model for mild traumatic brain injury (mTBI), we showed that axonal varicosities developed in a multi-focal fashion in the somatosensory cortex of the mice immediately after close-skull impact, consistent with our in vitro results4. It is important to note that our staining and imaging of the mTBI mice only provide a snap shot of neuronal morphological changes, since performing in vivo time-lapse imaging of neuronal morphology during a mechanical impact is still not feasible.
This fluid-puffing system allowed us not only to capture unique features associated with mechanical stress-induced varicosity formation, but also to determine the underlying mechanism. By testing different extracellular solutions, the blockers and openers of different candidates of mechanosensitive ion channels, and cellular electrophysiology, we identified that the transient receptor potential cation channel subfamily V member 4 (TRPV4) channel that is permeable to Ca2+ and Na+ and activated by puffing is mainly responsible for detecting initial mechanical stress during axonal varicosity formation4. This was further confirmed with an siRNA knockout approach. Taken together, this new assay system we have developed with hippocampal neuron culture, is highly valuable for studying the micromechanical properties of central neurons, especially in combination with other techniques.
This micromechanical system we have established is unique and differs from the previously-existing systems in several major aspects. First, in this system, the neurons experience out-of-plane mechanical stress in the forms of compression and shearing. During the mechanical impact, neuronal processes remain attached to the coverslip surface and do not move. This differs from other experimental systems that mainly involved bending and in-plane stretching (or tension), for instance, the deflection of bundled axons like moving strings5,6 or stretching axons grown on micropatterned channels and stretchable membranes7,8. Moreover, although axonal varicosities can also be induced in these assays like in our fluid-puffing system, the process in these settings takes much more time (from 10 min to several hours6,7,8) and appears irreversible. Finally, our system using local fluid puffing allows the examination of the spatial features of varicosity formation (e.g., dendrites, dendritic spines, soma, axonal initial segments, axonal terminals), besides its temporal features. Using this system, we discovered several unexpected and unique features of axonal varicosity formation, especially rapid onset, slow reversibility, and axon-dendrite polarity.
The system that we discuss in this paper is compatible with many techniques of molecular and cell biology. For instance, to study the effects of mechanical stress on neuronal morphology and function, it can be used together with myelin coculture, time-lapse imaging of fluorescent resonance energy transfer (FRET) and total internal reflection fluorescence (TIRF), calcium imaging, and patch clamp recording. In this paper, we focus on the core components of the system. Hippocampal neuron culture, the fluid-puffing setup, high-resolution time-lapse imaging for axonal transport, and calcium imaging are illustrated step-by-step below.

<table border="0" cellpadding="0" cellspacing="0" style="width:765px;" width="765">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="40">
			<td height="40" style="height:40px;width:341px;">12 mm coverslips&#160;</td>
			<td style="width:139px;">Warner Instruments&#160;</td>
			<td style="width:119px;">64-0702</td>
			<td style="width:167px;">for 24-well plate&#160;</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">25 mm coverslips&#160;</td>
			<td>Fisher Scientific&#160;</td>
			<td>12-545-102&#160;</td>
			<td>for 6-well plate&#160;</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Acetic acid</td>
			<td>Fisher Scientific&#160;</td>
			<td>A38-212</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Poly-D-lysine</td>
			<td>Sigma&#160;</td>
			<td>P6407</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Rat tail collagen&#160;</td>
			<td>Roche&#160;</td>
			<td>11 179 179 001&#160;</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">10X PBS&#160;</td>
			<td>National Diagnostics&#160;</td>
			<td>CL-253</td>
			<td></td>
		</tr>
		<tr height="40">
			<td align="left" height="40" style="height:40px;">Na2SO4</td>
			<td>Fisher Scientific&#160;</td>
			<td>S373-500</td>
			<td></td>
		</tr>
		<tr height="40">
			<td align="left" height="40" style="height:40px;">K2SO4</td>
			<td>Fisher Scientific&#160;</td>
			<td>P304-500</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">HEPES&#160;</td>
			<td>Fisher Scientific&#160;</td>
			<td>BP410-500</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">D-glucose&#160;</td>
			<td>Fisher Scientific&#160;</td>
			<td>D16-500</td>
			<td></td>
		</tr>
		<tr height="40">
			<td align="left" height="40" style="height:40px;">MgCl2</td>
			<td>Fisher Scientific&#160;</td>
			<td>BP214-500</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">NaOH</td>
			<td>Fisher Scientific&#160;</td>
			<td>SS255-1</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Protease enzyme&#160;</td>
			<td>Sigma&#160;</td>
			<td>P4032</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">FBS</td>
			<td>Gibco&#160;</td>
			<td>26140</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Sodium pyruvate&#160;</td>
			<td>Gibco&#160;</td>
			<td>11360-070</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">L-glutamine&#160;</td>
			<td>Gibco&#160;</td>
			<td>25030081</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Penicillin/Streptomycin 100x (P/S)</td>
			<td>Gibco&#160;</td>
			<td style="width:119px;">15140122</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">MEM Earle&#39;s Salts&#160;</td>
			<td>Gibco&#160;</td>
			<td>11090</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">B27 supplement&#160;</td>
			<td>Gibco&#160;</td>
			<td>17504-044</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Neurobasal&#160;</td>
			<td>Gibco&#160;</td>
			<td>21103-049</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Arabinosylcytosine (Ara-C)</td>
			<td>Sigma&#160;</td>
			<td>147-94-4</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Opti-MEM media&#160;</td>
			<td>Gibco&#160;</td>
			<td>31985-070</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Lipofectamine 2000</td>
			<td>Invitrogen&#160;</td>
			<td>1854313</td>
			<td>transfection reagent&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Borosilicate rods&#160;</td>
			<td>World Precision Instruments Inc.&#160;</td>
			<td>PG52151-4</td>
			<td>for puffing pipette&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">rubber tubing&#160;</td>
			<td style="width:139px;">Fisher Scientific&#160;</td>
			<td style="width:119px;">14-169-1A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">10cc plastic syringe and plunger</td>
			<td>Becton Dickinson&#160;</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">micromanipulator&#160;</td>
			<td>Sutter Instruments&#160;</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NaCl&#160;</td>
			<td>Fisher Scientific&#160;</td>
			<td>S640-3</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">KCl&#160;</td>
			<td>Fisher Scientific&#160;</td>
			<td>BP366-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td align="left" height="21" style="height:21px;">CaCl2</td>
			<td>Fisher Scientific&#160;</td>
			<td>C70-500</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:341px;">Cell culture dish (35 mm x 10 mm)</td>
			<td style="width:139px;">Corning&#160;</td>
			<td style="width:119px;">3294</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:341px;">Fluo-4 AM</td>
			<td style="width:139px;">Molecular Probes</td>
			<td style="width:119px;">F14201</td>
			<td style="width:167px;">for calcium imaging&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:341px;">Mito-YFP construct&#160;</td>
			<td style="width:139px;">Takara Bio Inc.&#160;</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">for cell transfection&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:341px;">YFP-N1 construct&#160;</td>
			<td style="width:139px;">Takara Bio Inc.&#160;</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">for cell transfection&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:341px;">Model P-1000 Flaming/Brown Micropipette puller&#160;</td>
			<td style="width:139px;">Sutter Instruments&#160;</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:341px;">Eclipse TE2000-U Mcroscope&#160;</td>
			<td style="width:139px;">Nikon</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:341px;">Plan Fluor ELWD 20x lens&#160;&#160;</td>
			<td style="width:139px;">Nikon</td>
			<td style="width:119px;">062933</td>
			<td style="width:167px;">objective&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:341px;">Apo TIRF 100x/1.49 oil lens&#160;</td>
			<td style="width:139px;">Nikon</td>
			<td style="width:119px;">MRD01991</td>
			<td style="width:167px;">objective&#160;</td>
		</tr>
	</tbody>
</table>

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.

Prior to puffing, axons normally show little varicosity formation. Following puffing with our standard pressure (190 mmH2O height), the axons start to develop many bead-like varicosities. The formation of varicosities is partially reversible, as shown by regions of the axon returning to their pre-puffed state following a 10 min recovery period (Figure 2A-B). After a longer period of recovery (&#62;20 min), some axons completely rec...

Watch this Scientific Journal Video about A Microbiomechanical System for Studying Varicosity Formation and Recovery in Central Neuron Axons at JoVE.com

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

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 ...

Research

JoVE Journal

Neuroscience

Systemic and Local Drug Delivery for Treating Diseases of the Central Nervous System in Rodent Models

Thorough preclinical testing of central nervous system (CNS) therapeutics includes a consideration of routes of administration and agent biodistribution ...

Optic Nerve Transection: A Model of Adult Neuron Apoptosis in the Central Nervous System

Retinal ganglion cells (RGCs) are CNS neurons that output visual information from the retina to the brain, via the optic nerve. 
The optic nerve can be ...

Morphological Analysis of Drosophila Larval Peripheral Sensory Neuron Dendrites and Axons Using Genetic Mosaics

Morphological Analysis of Drosophila Larval Peripheral Sensory Neuron Dendrites and Axons Using Genetic Mosaics

Nervous system development requires the correct specification of neuron position and identity, followed by accurate neuron class-specific dendritic ...

In ovo Electroporation in Chick Midbrain for Studying Gene Function in Dopaminergic Neuron Development

In ovo Electroporation in Chick Midbrain for Studying Gene Function in Dopaminergic Neuron Development

Dopaminergic neurons located in the ventral midbrain control movement, emotional behavior, and reward mechanisms1-3. The dysfunction of ventral midbrain ...

Production of Lentiviral Vectors for Transducing Cells from the Central Nervous System

Efficient gene delivery in the central nervous system (CNS) is important in studying gene functions, modeling neurological diseases and developing ...

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

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

Direct Intraventricular Delivery of Drugs to the Rodent Central Nervous System

Due to an inability to cross the blood brain barrier, certain drugs need to be directly delivered into the central nervous system (CNS). Our lab focuses ...

Immunohistochemical Analysis in the Rat Central Nervous System and Peripheral Lymph Node Tissue Sections

Immunohistochemistry (IHC) provides highly specific, reliable and attractive protein visualization. Correct performance and interpretation of an IHC-based ...

Laser Nanosurgery of Cerebellar Axons In Vivo

Laser Nanosurgery of Cerebellar Axons In Vivo

Only a few neuronal populations in the central nervous system (CNS) of adult mammals show local regrowth upon dissection of their axon. In order to ...

In vivo Optogenetic Stimulation of the Rodent Central Nervous System

In vivo Optogenetic Stimulation of the Rodent Central Nervous System

The ability to probe defined neural circuits in awake, freely-moving animals with cell-type specificity, spatial precision, and high temporal resolution ...