Name: transcranial electrical brain stimulation in alert rodents
Uploaded: 2017-11-02T14:00:00
Description: Watch this Scientific Journal Video about Transcranial Electrical Brain Stimulation in Alert Rodents at JoVE.com

This work was supported by the German Research Foundation (DFG RE 2740/3-1). We thank Frank Huethe and Thomas G&#252;nther for the in-house production of the custom-made tES set-up and DC-stimulator.

For research involving animals, the relevant (country-specific) approvals must be obtained before starting experiments. All animal experiments reported here are performed according to the EU directive 2010/63/EU, the updated German animal protection law (&#34;Tierschutzgesetz&#34;) of July 2013, and the updated German animal research regulations of August 2013. Animal protocols have been approved by the local authorities &#34;Commission for Animal Experimentation of the Regional Council of Freiburg&#34; and &#34;Commissi...

<ol>
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This protocol describes typical materials and procedural steps for surgical realization of a permanent tES set-up, as well as for subsequent stimulation in alert rodents. During preparation of a rodent tES experiment, several methodological aspects (safety and tolerability of tES, outcome parameter) as well as conceptual aspects (comparability with human condition, anticipated effects of stimulation on a particular brain region) need to be taken into account. From a methodological point of view, the surgical set-up of th...

The transcranial administration of electrical currents to the brain (tES) has been used for decades to study brain function and to modify behavior. More recently, applying direct currents, or less frequently alternating currents (tACS and tRNS), noninvasively through the intact skull by use of two or more electrodes (anode(s) and cathode(s)) has gained scientific and clinical interest. In particular, tDCS has been used in more than 33,200 sessions in healthy subjects and patients with neuropsychiatric diseases and has emerged as a safe and easy, cost-effective bedside application, with possible therapeutic potential as well as long-lasting behavioral effects1. This clearly yielded the increased need and scientific interest in mechanistic studies, including safety aspects. This article focuses on the most commonly used form of stimulation, tDCS.
Across species, tDCS modulates cortical excitability and synaptic plasticity. Excitability changes have been reported as polarity-dependent alteration of spontaneous neuronal firing rate in rats and cats2,3,4, or as changes in motor evoked potential (MEP) amplitudes in humans and mice (both increased after anodal and decreased after cathodal tDCS: human5,6; mouse7). Anodal DCS increased synaptic efficacy of motor cortical or hippocampal synapses in vitro for several hours after stimulation or long term potentiation (LTP), when co-applied with a specific weak synaptic input or when given before a plasticity inducing stimulation8,9,10,11,12. In accordance, the benefits of stimulation on motor or cognitive training success are often revealed only if tDCS is co-applied with training8,13,14,15. While these previous findings are mainly attributed to functions of neurons, it should be noted that non-neuronal cells (glia) may also contribute to functional effects of tDCS. For instance, astrocytic intracellular calcium levels increased during anodal tDCS in alert mice16. Similarly, anodal tDCS at current densities below the threshold for neurodegeneration induced a dose dependent activation of microglia17. However, the modulation of neuron-glia interaction by tDCS needs further specific investigation.
Taken together, animal research clearly advanced our understanding of the modulatory effect of tDCS on excitability and plasticity. However, there is an &#34;inverse translational gap&#34; observable in the exponential increase in publications of human tDCS studies in contrast to the slow and minor increase in investigations of the underlying mechanisms of tES in in vitro and in vivo animal models. Additionally, rodent tES models are performed with high variability across research laboratories (ranging from transdermal to epicranial stimulation), and reported stimulation procedures are often not fully transparent hindering the comparability and replicability of basic research data as well as interpretation of results.
Here, we describe in detail the surgical implementation of a transcranial brain stimulation set-up targeting the primary motor cortex, which allows translation to the human tDCS condition while minimizing variability, and allows repeated stimulation without hindering behavior. A step-by-step protocol for subsequent tES in alert rats is provided. Methodological and conceptual aspects of safe application of tES in alert rodents are discussed.

<table>
	<tbody>
		<tr>
			<td>Softasept N</td>
			<td>B. Braun Melsungen AG, 
			Melsungen, Deutschland</td>
			<td>3887138</td>
			<td>antiseptic agent</td>
		</tr>
		<tr>
			<td>Ethanol 70 %</td>
			<td>Carl Roth GmbH &#38; Co. KG, Karlsruhe, Deutschland</td>
			<td>T913.1</td>
			<td></td>
		</tr>
		<tr>
			<td>arched tip forceps</td>
			<td>FST Fine science tools, Heidelberg, Deutschland</td>
			<td>11071-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Iris Forceps, 10cm, Straight, Serrated</td>
			<td>World Precision Instruments, Inc, Sarasota, FL, USA, Inc, Sarasota, FL, USA</td>
			<td>15914</td>
			<td></td>
		</tr>
		<tr>
			<td>Scalpel Handle #3, 13cm</td>
			<td>World Precision Instruments, Inc, Sarasota, FL, USA, Inc, Sarasota, FL, USA</td>
			<td>500236</td>
			<td></td>
		</tr>
		<tr>
			<td>Standard Scalpel Blade #10</td>
			<td>World Precision Instruments, Inc, Sarasota, FL, USA, Inc, Sarasota, FL, USA</td>
			<td>500239</td>
			<td></td>
		</tr>
		<tr>
			<td>Zelletten cellulose swabs</td>
			<td>Lohmann und Rauscher, Neuwied, Deutschland</td>
			<td>13349</td>
			<td>5 x 4 cm&#160;</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>AbbVie Deutschland GmbH &#38; Co</td>
			<td>N01AB06</td>
			<td></td>
		</tr>
		<tr>
			<td>Iris Scissors, 11.5cm, Straight</td>
			<td>World Precision Instruments, Inc, Sarasota, FL, USA, Inc, Sarasota, FL, USA</td>
			<td>501758</td>
			<td>small scissors</td>
		</tr>
		<tr>
			<td>cotton swab/cotton buds</td>
			<td>Carl Roth GmbH &#38; Co. KG, Karlsruhe, Deutschland</td>
			<td>EH12.1</td>
			<td>Rotilabo</td>
		</tr>
		<tr>
			<td>Kelly Hemostatic Forceps, 14cm, Straight</td>
			<td>World Precision Instruments, Inc, Sarasota, FL, USA, Inc, Sarasota, FL, USA</td>
			<td>501241</td>
			<td>surgical clamp</td>
		</tr>
		<tr>
			<td>electrode plate (platinum)</td>
			<td>custom made</td>
			<td>Wissenschaftliche Werkstatt Neurozentrum Uniklinik Freiburg, Deutschland</td>
			<td>10x6 mm, 0.15 mm thickness</td>
		</tr>
		<tr>
			<td>insulated copper strands (~1 mm diameter)</td>
			<td>Reichelt elektronik GmbH &#38; Co. KG, Sande, Germany</td>
			<td>LITZE BL</td>
			<td>electrode cable</td>
		</tr>
		<tr>
			<td>Weller EC 2002 M soldering station</td>
			<td>Weller Tools GmbH, Besigheim, Germany</td>
			<td>EC2002M1D</td>
			<td></td>
		</tr>
		<tr>
			<td>Iso-Core EL 0,5 mm</td>
			<td>FELDER GMBH L&#246;ttechnik, Oberhausen, Deutschland</td>
			<td>20970510</td>
			<td>lead free solder</td>
		</tr>
		<tr>
			<td>MERSILENE Polyester Fiber Suture</td>
			<td>Johnson &#38; Johnson Medical GmbH, Ethicon Deutschland, Norderstedt, Germany</td>
			<td>R871H</td>
			<td>nonabsorbable braided suture, 4-0</td>
		</tr>
		<tr>
			<td>Histoacryl</td>
			<td>B. Braun Melsungen AG, 
			Melsungen, Deutschland</td>
			<td>9381104</td>
			<td>cyanoacrylate</td>
		</tr>
		<tr>
			<td>Ketamin 10%</td>
			<td>Medistar GmbH, Germany</td>
			<td>n/a</td>
			<td>anesthetics</td>
		</tr>
		<tr>
			<td>Rompun 2% (Xylazine)</td>
			<td>Bayer GmbH, Germany</td>
			<td>n/a</td>
			<td>anesthetics</td>
		</tr>
	</tbody>
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transcranial electrical brain stimulation in alert rodents

Transcranial electrical brain stimulation can modulate cortical excitability and plasticity in humans and rodents. The most common form of stimulation in humans is transcranial direct current stimulation (tDCS). Less frequently, transcranial alternating current stimulation (tACS) or transcranial random noise stimulation (tRNS), a specific form of tACS using an electrical current applied randomly within a pre-defined frequency range, is used. The increase of noninvasive electrical brain stimulation research in humans, both for experimental and clinical purposes, has yielded an increased need for basic, mechanistic, safety studies in animals. This article describes a model for transcranial electrical brain stimulation (tES) through the intact skull targeting the motor system in alert rodents. The protocol provides step-by-step instructions for the surgical set-up of a permanent epicranial electrode socket combined with an implanted counter electrode on the chest. By placing a stimulation electrode into the epicranial socket, different electrical stimulation types, comparable to tDCS, tACS, and tRNS in humans, can be delivered. Moreover, the practical steps for tES in alert rodents are introduced. The applied current density, stimulation duration, and stimulation type may be chosen depending on the experimental needs. The caveats, advantages, and disadvantages of this set-up are discussed, as well as safety and tolerability aspects.

The described implementation of a set-up for reliable repeated tES in alert rodents can be easily integrated into mechanistic experiments, dose-response studies, or experiments including behavioral tasks. To date, the comparability of data from animal studies using (noninvasive) tES is hindered by the variability of the tES stimulation set-ups between laboratories and by differences in stimulation parameters (e.g., various current densities applied at exorbitant high levels compa...

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Transcranial Electrical Brain Stimulation in Alert Rodents

This protocol describes a surgical set-up for a permanent epicranial electrode socket and an implanted chest electrode in rodents. By placing a second electrode into the socket, different types of transcranial electrical brain stimulation can be delivered to the motor system in alert animals through the intact skull.

Transcranial electrical brain stimulation can modulate cortical excitability and plasticity in humans and rodents. The most common form of stimulation in ...

Research

JoVE Journal

Neuroscience

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Transcranial Direct Current Stimulation (tDCS) in Mice

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The abundance of neuroimaging data and rapid development of machine learning has made it possible to investigate brain activation patterns. However, ...