We thank Shaili Jha and Heather Decot for assistance with filming.

Ethics Statement: This procedure is in accordance with the National Institutes of Health Guidelines for Animal Research (Guide for the Care and Use of Laboratory Animals) and is approved by the University of North Carolina Institutional Animal Care and Use Committee.
1. Electrode Implantation
The first step is electrode implantation. In this step, an electrode is unilaterally implanted into the subthalamic nucleus (STN), a small nucleus with translational significance...

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Simultaneous DBS and fMRI represents a promising experimental toolkit for the identification and characterization of global downstream responses to neural circuit stimulation, in vivo.&#160;The major advantage of this technique over other available tools, such as electrophysiological recordings, lies in the relatively unbiased nature of fMRI, whereby a large and diverse area of brain tissue can be examined for responsiveness to DBS at any target. Although the described protocol is specific for DBS-fMRI in the ra...

Determining the global downstream effects of neural circuit activity represents a major challenge and goal for many areas of systems neuroscience. A paucity of tools are currently available that meet this need, and thus there is a demand for increased accessibility of the appropriate experimental setups.&#160;One such method for evaluating the global consequence of neural circuit activation relies on the simultaneous application of deep brain electrical stimulation (DBS) and functional MRI (fMRI). DBS-fMRI allows for the detection of downstream responses to circuit activation on a large spatial scale, and can be applied at virtually any stimulation target. This toolset is highly suitable for translational preclinical studies, including the characterization of responses to therapeutic high frequency stimulation.
In addition to access to a suitable MRI scanner, successful DBS-fMRI experiments require consideration of a number of variables, including electrode type, sedation method, and maintenance of physiological parameters.&#160;For example, electrode choice should be based on factors relating to stimulation efficacy (e.g.&#160;lead size and conductance, mono- vs. bipolar), as well as MR compatibility and electrode artifact size. Electrode artifacts vary according to electrode material and size, as well as the scan sequence used; thorough pre-experimental testing should be employed to determine the appropriate electrode type for each study. In general, tungsten microwire electrodes are recommended for this protocol. Choice of paralytic and sedative should be made to effectively immobilize the animal and reduce the suppressive effects of certain sedatives on blood-oxygen-level-dependent (BOLD) signal.&#160;Lastly, it is critical to maintain the animal at optimal physiological parameters, including body temperature and oxygen saturation.
The protocol that we have developed for DBS-fMRI overcomes many of these potential obstacles, and in our hands, provides robust and consistent results.&#160;Additionally, these experimental procedures may be readily adopted for the combination of fMRI with alternative stimulation methods, including optogenetic stimulation.&#160;

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			<td height="22" style="height:22px;width:216px;">Isoflurane (Forane)</td>
			<td style="width:71px;">Baxter</td>
			<td style="width:119px;">1001936060</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:216px;">Dexmedetomidine (Dexdomitor)</td>
			<td style="width:71px;">Pfizer</td>
			<td style="width:119px;">145108-58-3</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:216px;">Pancuronium Bromide</td>
			<td style="width:71px;">Selleckchem</td>
			<td style="width:119px;">S2497</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:216px;">9.4T Small Animal MRI</td>
			<td style="width:71px;">Bruker</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">BioSpec System with BGA-9S gradient</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:216px;">Sterotactic Frame</td>
			<td style="width:71px;">Kopf</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Model 962</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:216px;">Small Animal Ventilator</td>
			<td style="width:71px;">CWE, Inc.&#160;</td>
			<td style="width:119px;">12-02100</td>
			<td style="width:167px;">Model SAR-830</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:216px;">Dental Cement</td>
			<td style="width:71px;">A-M Systems</td>
			<td style="width:119px;">525000</td>
			<td style="width:167px;">Teets Cold Curing</td>
		</tr>
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			<td height="85" style="height:85px;width:216px;">MouseOx Plus System</td>
			<td style="width:71px;">STARR Life Science Corp.</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:216px;">Capnometer</td>
			<td style="width:71px;">Surgivet, Smith Medical</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">V9004 Series</td>
		</tr>
		<tr height="85">
			<td height="85" style="height:85px;width:216px;">Stimulus Isolator</td>
			<td style="width:71px;">World Precision Instruments</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Model A365</td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:216px;">MR-compatible Brass Screws</td>
			<td style="width:71px;">McMaster Carr</td>
			<td>94070A031</td>
			<td style="width:167px;">0-80 thread size, 1/4 inch. Can be cut to desired length.</td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:216px;">Tungsten Wire</td>
			<td style="width:71px;">California Fine Wire Company</td>
			<td>100211</td>
			<td style="width:167px;">Used to construct MR-compatible stimulating microelectrode</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:216px;">Syringe Pump</td>
			<td style="width:71px;">Harvard Appartus</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Model PHD 2000 (not MRI-compatible)</td>
		</tr>
	</tbody>
</table>

deep brain stimulation with simultaneous fmri in rodents

In order to visualize the global and downstream neuronal responses to deep brain stimulation (DBS) at various targets, we have developed a protocol for using blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) to image rodents with simultaneous DBS. DBS fMRI presents a number of technical challenges, including accuracy of electrode implantation, MR artifacts created by the electrode, choice of anesthesia and paralytic to minimize any neuronal effects while simultaneously eliminating animal motion, and maintenance of physiological parameters, deviation from which can confound the BOLD signal.&#160;Our laboratory has developed a set of procedures that are capable of overcoming most of these possible issues. For electrical stimulation, a homemade tungsten bipolar microelectrode is used, inserted stereotactically at the stimulation site in the anesthetized subject. In preparation for imaging, rodents are fixed on a plastic headpiece and transferred to the magnet bore. For sedation and paralysis during scanning, a cocktail of dexmedetomidine and pancuronium is continuously infused, along with a minimal dose of isoflurane; this preparation minimizes the BOLD ceiling effect of volatile anesthetics. In this example experiment, stimulation of the subthalamic nucleus (STN) produces BOLD responses which are observed primarily in ipsilateral cortical regions, centered in motor cortex. Simultaneous DBS and fMRI allows the unambiguous modulation of neural circuits dependent on stimulation location and stimulation parameters, and permits observation of neuronal modulations free of regional bias. This technique may be used to explore the downstream effects of modulating neural circuitry at nearly any brain region, with implications for both experimental and clinical DBS.

Representative functional data were acquired according to the above protocol in a single rat with a stimulating electrode implanted to the subthalamic nucleus on the right side. An illustration of essential setup for DBS fMRI image acquisition is provided in Figure 1. Stimulation was applied consistent with the above protocol, with an amplitude of 0.3 mA, frequency of 130 Hz and pulse width of 0.09 msec. Robust activation of ipsilateral motor cortex has been consistently visualized using this protocol wi...

Watch this Scientific Journal Video about Deep Brain Stimulation with Simultaneous fMRI in Rodents at JoVE.com

Deep Brain Stimulation with Simultaneous fMRI in Rodents

This protocol describes a standard method for simultaneous functional magnetic resonance imaging and deep brain stimulation in the rodent. The combined use of these experimental tools allows for the exploration of global downstream activity in response to electrical stimulation at virtually any brain target.

In order to visualize the global and downstream neuronal responses to deep brain stimulation (DBS) at various targets, we have developed a protocol for ...

deep-brain-stimulation-with-simultaneous-fmri-in-rodents

Research

JoVE Journal

Neuroscience

13.9K visualizações.  University of North Carolina.  Este protocolo descreve um método padrão para simultânea ressonância magnética funcional e estimulação cerebral profunda no roedor. O uso combinado dessas ferramentas experimentais permite a exploração de actividade a jusante global em resposta à estimulação elétrica em praticamente qualquer alvo cérebro. 