Name: Video: Implanting an Electrode Array and Optic Fiber into the Mouse Hippocampus - Concept
Uploaded: 2025-01-30T14:42:52.000+00:00
Duration: 1 min 17 s
Description: 68 Views. Source: Bender, F., et. al., Optogenetic Entrainment of Hippocampal Theta Oscillations in Behaving Mice. J. Vis. Exp. (2018) This video demonstrates the stereotactic implantation of a wire electrode array and an optic fiber in the hippocampus of a mouse model.

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All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
1. Preparation of Optic Fibers (Figure 1A)
<ol>
	<li>Use multimode optic fiber (105 &#181;m core, glass-clad with silica core, 0.22 NA). Strip the 125 &#181;m cladding of the fiber core using a micro-stripper while the fiber is still attached to the fiber spool.</li>
	<li>Cut the fiber to a length of approximately 2-3 cm using a diamond knife.</li>
	<li>Insert the fiber in a zirconia ceramic stick ferrule (ID: 126 &#181;m). Approximately 0.5-1 mm of the optic fiber should protrude from the convex side of the ferrule.</li>
	<li>Using a needle, apply one drop of epoxy glue to both ends of the ferrule but not onto the sides of the ferrule. Alternatively, use super glue.</li>
	<li>Allow the glue to dry for at least 30 min.</li>
	<li>Polish the convex side of the ferrule using diamond lapping fiber polishing film (3 &#181;m grits).</li>
	<li>Test the fidelity of light transfer using an optical power meter.
	<ol>
		<li>Set the wavelength on the power meter to the same wavelength as the laser being used.</li>
		<li>Position the patch cord with the tip facing the center of the sensor. Power on the laser and read the light output from the power meter. Record the value.</li>
		<li>Connect the optic fiber to the patch cord via a mating sleeve and position it with the tip of the fiber facing the center of the sensor. Power on the laser and read the light output from the power meter. Record the value.</li>
		<li>Calculate the transmission rate by dividing the second value by the first value. If the transmission rate is below 0.5, discard the fiber; otherwise, use it for implantation.</li>
		<li>Test the transmission rate for each fiber before implantation.</li>
		<li>For later experiments, adjust the laser&#39;s light intensity output to the transmission rate of the optic fiber: Set the light output from the patch cord tip to 5-15 divided by the transmission rate to achieve a final light output from the fiber tip of 5-15 mW.</li>
	</ol>
	</li>
</ol>
2. Preparation of Tungsten Wire Arrays for LFP Recordings (Figure 1B)
<ol>
	<li>Glue several (for example 6) 100 &#181;m silica tube guides in parallel to the sticky side of a piece of tape. Cut one piece, approximately 4-6 mm, for one wire array assembly.</li>
	<li>Thread formvar-insulated 45 &#181;m tungsten wires through the guide tubes using forceps.</li>
	<li>Strip six enamel-insulated fine copper bonding wires (approximately 5 mm long) and a grounding wire (approximately 2-3 cm long) by using a scalpel to scrape away the insulation on both ends. Solder them to the nanoconnector pins.</li>
	<li>Connect each bonding wire to one tungsten wire using one drop of silver conductive paint, respectively. Let dry for at least 30 min.</li>
	<li>Apply a minimum amount of cement to cover the wires. Do not apply cement to the tungsten wires, which will be inserted in the brain tissue, or to the upper part of the nano connector. Let the cement dry for at least 30 minutes.</li>
	<li>Perform an angular cut (5-20&#176;) of the tungsten wires using blunt stainless-steel scissors to enable reliable implantation of wires below or above the zone ventrally adjacent to the stratum pyramidale, where theta amplitude is too low to estimate the entrainment fidelity.</li>
	<li>Deinsulate the tip (approximately 2 mm) of the ground wire by using a scalpel to scrape away the insulation. Treat it with flux and pre-solder.</li>
	<li>Check potential cross-talks between electrodes using a digital multimeter. Connect the connector pins to the multimeter, which must be set to the resistance measurement mode. Check pairwise combinations of channels; a reading on the multimeter below 5 M&#937; indicates significant cross-talk.</li>
	<li>Use an impedance meter to check the impedance of each wire electrode in saline. Typical impedance values are below 100 k&#937;.</li>
	<li>To facilitate implantation, glue one optic fiber to the wire array so that the tip of the fiber is at the level of the shortest wire and the fiber tip is in close proximity but not touching the tungsten wires. Keep the angle of the fiber as small as possible in order to prevent tissue damage during implantation.</li>
</ol>
3. Stereotaxic Implantations
<ol>
	<li>Remove the connective tissue from the top of the skull and thoroughly push down the neck muscles by approximately 2 mm to prevent muscle artifacts during the recording.</li>
	<li>Clean the skull using a cotton-tip applicator and saline, and drill four holes (2 in the front and two above the cerebellum, 0.8 mm diameter) to place bone stainless-steel screws (00-96x1/16) for ground and stabilization of the implant (Figure 1D). Position the ground screw, connected to one copper wire (approximately 2-3 cm in length) above the cerebellum.</li>
	<li>Cover the ground-screw completely with cement to prevent muscle artifacts during the electrophysiological recordings. Build a cement ring connecting all screws (Figure 1E).</li>
	<li>Perform a craniotomy above the implantation side (Hippocampus, AP -1.94, L 1.4, V 1.4 in reference to the bregma). Apply approximately 5 &#181;L of sterile NaCl on the surface of the brain tissue.</li>
	<li>Slowly lower the wire array using stereotaxis in the craniotomy. For unitary recordings, implant a silicone probe instead of a wire array. To prevent optoelectric light artifacts, implant the optic fiber separately in the hippocampus with the fiber tip not directly facing the probe (Figure 1C&#8212;I). For investigation of the coordination of the entrainment between hemispheres, implant an additional optic fiber in the contralateral hippocampal CA1 area.</li>
	<li>To protect brain tissue, apply approximately 5 &#181;L of warm liquid wax/paraffin oil, preheated at 70 &#176;C, with a syringe above the implantation site.</li>
	<li>Apply cement around the wire array and cover the skull with cement.</li>
	<li>Apply one drop of flux to the pre-soldered ground/reference wire and the pre-soldered wire connected to the ground screw using, for instance, a needle, and fuse the wires using a soldering machine.</li>
	<li>Cover the entire ground wire with cement.</li>
	<li>Administer 0.3 mL Erycinum (1:4 in sterile NaCl) and carprofen (5mg/mL) i.p. after surgery and for at least the two days following. The mouse typically wakes up within 15 min following surgery. Warm the animal with a red lamp to speed up recovery.</li>
	<li>Monitor the mouse&#39;s weight daily for the first week following the surgery or until it is stable. Weight loss should not exceed 10% of the mouse&#39;s recorded weight before surgery. To accelerate weight stabilization, supply the mouse with wet food and condensed milk during the first days following the surgery.</li>
	<li>To record hippocampal cellular activity during entrainment, implant a silicone probe in the hippocampus (AP -1.94, L 1.4, V 1, with subsequent lowering) (Figure 1C&#8212;I). Implant the optic fiber in the hippocampus at AP -3, L 1.4, V 1.6, 39&#176; caudal-rostral. If stimulation of cell somata is desired, implant an additional optic fiber in the MS (AP +0.98, L 1, V 3.9, 15&#176; lateral).</li>
</ol>

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>PV-Cre mice</td>
			<td>The Jackson Laboratory</td>
			<td>B6;129P2-Pvalbtm1(cre)Arbr/J</td>
			<td></td>
		</tr>
		<tr>
			<td>Stereotaxis</td>
			<td>David Kopf Instruments, Tujunga, CA, USA</td>
			<td>Model 963</td>
			<td>Ultra precise small animal stereotaxic instrument</td>
		</tr>
		<tr>
			<td>Drill bits, 0.8 mm</td>
			<td>Bijoutil, Allschwil, Switzerland</td>
			<td>49080HM</td>
			<td></td>
		</tr>
		<tr>
			<td>Soldering station</td>
			<td>Weller Tools GmbH, Besigheim, Germany</td>
			<td>WSD 81</td>
			<td></td>
		</tr>
		<tr>
			<td>Erythromycin</td>
			<td>Rotexmedica GmbH, Trittau, Germany</td>
			<td>PZN: 10823932</td>
			<td>1g powder for solution for infusion</td>
		</tr>
		<tr>
			<td>Precision drill/grinder</td>
			<td>Proxxon, Wecker, Luxemburg</td>
			<td>fbs 240/e</td>
			<td></td>
		</tr>
		<tr>
			<td>Multimode optic fiber</td>
			<td>ThorLabs, Dachau, Germany</td>
			<td>FG105LCA</td>
			<td>0.22 NA, Low-OH, &#216;105 &#181;m Core, 400 - 2400 nm</td>
		</tr>
		<tr>
			<td>Ceramic stick ferrule</td>
			<td>Precision Fiber Products, Milpitas, CA, USA</td>
			<td>CFLC126</td>
			<td>Ceramic LC MM Ferrule, ID 126um</td>
		</tr>
		<tr>
			<td>Polishing paper</td>
			<td>Thorlabs</td>
			<td>LF3D</td>
			<td>6&#34; x 6&#34; Diamond Lapping (Polishing) Sheet</td>
		</tr>
		<tr>
			<td>Power meter</td>
			<td>Thorlabs</td>
			<td>PM100D</td>
			<td>Compact Power and Energy Meter Console, Digital 4&#34; LCD</td>
		</tr>
		<tr>
			<td>Multimode fiber optic coupler</td>
			<td>Thorlabs</td>
			<td>FCMM50-50A-FC</td>
			<td>1x2 MM Coupler, 50:50 Split Ratio, 50 &#181;m GI Fibers, FC/PC</td>
		</tr>
		<tr>
			<td>Fiberoptic patch cord</td>
			<td>Thorlabs</td>
			<td>FG105LCA CUSTOM-MUC</td>
			<td>custom made, 3 m long, with protective tubing, Tubing: FT030, Connector 1: FC/PC, Connector 2: 1.25mm (LC) Ceramic Ferrule</td>
		</tr>
		<tr>
			<td>Sleeve</td>
			<td>Precision Fiber Products, Milpitas, CA, USA</td>
			<td>ADAL1</td>
			<td>Ceramic Split Mating Sleeve for &#216;1.25 mm (LC/PC) Ferrules</td>
		</tr>
		<tr>
			<td>Tungsten wires</td>
			<td>California Fine Wire Company, Grover Beach, CA, USA</td>
			<td>CFW0010954</td>
			<td>40 &#181;m, 99.95%</td>
		</tr>
		<tr>
			<td>Capillary tubing</td>
			<td>Optronics</td>
			<td>1068150020</td>
			<td>ID: 100.4 &#181;m</td>
		</tr>
		<tr>
			<td>Omnetics nanoconnector</td>
			<td>Omnetics Connector Corporation, Minneapolis, USA</td>
			<td>A79038-001</td>
			<td></td>
		</tr>
		<tr>
			<td>Screws</td>
			<td>Bilaney, D&#252;sseldorf, Germany</td>
			<td>00-96x1/16</td>
			<td>stainless-steel</td>
		</tr>
		<tr>
			<td>Silver conductive paint</td>
			<td>Conrad electronics, Germany</td>
			<td>530042</td>
			<td></td>
		</tr>
		<tr>
			<td>Liquid flux</td>
			<td>Felder GMBH L&#246;ttechnik, Oberhausen, Germany</td>
			<td>L&#246;t&#246;l ST</td>
			<td>DIN EN 29454.1, 3.2.2.A (F-SW 11)</td>
		</tr>
	</tbody>
</table>

implanting an electrode array and optic fiber into the mouse hippocampus

Source: Bender, F., et. al., <a href="https://appjove.unicartagenaproxy.elogim.com/v/57349">Optogenetic Entrainment of Hippocampal Theta Oscillations in Behaving Mice.</a> J. Vis. Exp. (2018)
This video demonstrates the stereotactic implantation of a wire electrode array and an optic fiber in the hippocampus of a mouse model.

<img alt="Figure 1" src="/files/ftp_upload/22947/22947_Figure1.jpg" /> 
Figure 1: Illustration of optic fibers, electrodes and surgery. (A) Illustration of an optic fiber. (B) Illustration of a wire array glued to an optic fiber for the recording of hippocampal LFP during entrainment of hippocampal theta oscillations. (C) For recording of the hippocampal cellular activity, a silicone probe is mounted on a microdrive....

Implanting an Electrode Array and Optic Fiber into the Mouse Hippocampus

All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
1. ...

Take an immobilized anesthetized mouse with its skull exposed.
Drill holes rostral to the coronal suture and above the cerebellum.
Insert stainless-steel screws into the drilled sites rostral to the coronal suture for implant stabilization.
Insert the ground and reference screws above the cerebellum to minimize electrical noise.
Cover these screws with cement to prevent muscle artifacts during the recordings. Secure the other screws with cement.
Drill holes in the skull, exposing the hippocampal tissue. Apply saline to maintain tissue hydration.&#160;
Lower the optic fiber and electrode array through the holes into the hippocampus for optical stimulation and targeted neural activity recording.
Apply warm wax around the implantation site to protect the tissue.
Encase the implant and skull in cement to stabilize them.
Solder the ground and reference wires to the electrode array to ensure a stable electrical connection.
Cover the wires with cement.
Return the mouse to its cage for recovery.

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Stimulation and Modulation Techniques

68 Views. Source: Bender, F., et. al., Optogenetic Entrainment of Hippocampal Theta Oscillations in Behaving Mice. J. Vis. Exp. (2018) This video demonstrates the stereotactic implantation of a wire electrode array and an optic fiber in the hippocampus of a mouse model. 

Video: Implanting an Electrode Array and Optic Fiber into the Mouse Hippocampus - Concept

Microelectrode Guided Implantation of Electrodes into the Subthalamic Nucleus of Rats for Long-term Deep Brain Stimulation

Deep brain stimulation (DBS) is a widely used and effective therapy for several neurologic disorders, such as idiopathic Parkinson&#8217;s disease, dystonia or tremor. DBS is based on the delivery of electrical stimuli to specific deep anatomic structures of the central nervous system. However, the mechanisms underlying the effect of DBS remain enigmatic. This has led to an interest in investigating the impact of DBS in animal models, especially in rats. As DBS is a long-term therapy, research should be focused on molecular-genetic changes of neural circuits that occur several weeks after DBS. Long-term DBS in rats is challenging because the rats move around in their cage, which causes problems in keeping in place the wire leading from the head of the animal to the stimulator. Furthermore, target structures for stimulation in the rat brain are small and therefore electrodes cannot easily be placed at the required position. Thus, a set-up for long-lasting stimulation of rats using platinum/iridium electrodes with an impedance of about 1 M&#937; was developed for this study. An electrode with these specifications allows for not only adequate stimulation but also recording of deep brain structures to identify the target area for DBS. In our set-up, an electrode with a plug for the wire was embedded in dental cement with four anchoring screws secured onto the skull. The wire from the plug to the stimulator was protected by a stainless-steel spring. A swivel was connected to the circuit to prevent the wire from becoming tangled. Overall, this stimulation set-up offers a high degree of free mobility for the rat and enables the head plug, as well as the wire connection between the plug and the stimulator, to retain long-lasting strength.

A method for implanting electrodes into the subthalamic nucleus (STN) of rats is described. Better localization of the STN was achieved by using a microrecording system. Furthermore, a stimulation set-up is presented that is characterized by long-lasting connections between the head of the animal and the stimulator.

Deep brain stimulation (DBS) is a widely used and effective therapy for several neurologic disorders, such as idiopathic Parkinson&#8217;s disease, ...

JoVE Journal

Chronic Implantation of Multiple Flexible Polymer Electrode Arrays

Simultaneous recordings from large populations of individual neurons across distributed brain regions over months to years will enable new avenues of scientific and clinical development. The use of flexible polymer electrode arrays can support long-lasting recording, but the same mechanical properties that allow for longevity of recording make multiple insertions and integration into a chronic implant a challenge. Here is a methodology by which multiple polymer electrode arrays can be targeted to a relatively spatially unconstrained set of brain areas.
The method utilizes thin-film polymer devices, selected for their biocompatibility and capability to achieve long-term and stable&#160;electrophysiologic recording interfaces. The resultant implant allows accurate and flexible targeting of anatomically distant regions, physical stability for months, and robustness to electrical noise. The methodology supports up to sixteen serially inserted devices across eight different anatomic targets. As previously demonstrated, the methodology is capable of recording from 1024 channels. Of these, the 512 channels in this demonstration used for single neuron recording yielded 375 single units distributed across six recording sites. Importantly, this method also can record single units for at least 160 days.
This implantation strategy, including temporarily bracing each device with a retractable silicon insertion shuttle, involves tethering of devices at their target depths to a skull-adhered plastic base piece that is custom-designed for each set of recording targets, and stabilization/protection of the devices within a silicone-filled, custom-designed plastic case. Also covered is the preparation of devices for implantation, and design principles that should guide adaptation to different combinations of brain areas or array designs.

Described below is a method for implantation of multiple polymer electrode arrays across anatomically distant brain regions for chronic electrophysiological recording in freely moving rats. Preparation and surgical implantation are described in detail, with emphasis on design principles to guide adaptation of these methods for use in other species.

Simultaneous recordings from large populations of individual neurons across distributed brain regions over months to years will enable new avenues of ...

Preparation and Implantation of Electrodes for Electrically Kindling VGAT-Cre Mice to Generate a Model for Temporal Lobe Epilepsy

It was discovered that electrical kindling of VGAT-Cre mice led to the spontaneous motor and electrographic seizures. A recent paper focused on how unique VGAT-Cre mice were used in developing spontaneous recurring seizures (SRS) after kindling and a likely mechanism - insertion of Cre into the VGAT gene - disrupted its expression and reduced GABAergic tone. The present study extends these observations to a larger cohort of mice, focusing on key issues such as how long the SRS continues after kindling and the effect of the animal's sex and age. This report describes the protocols for the following key steps: making headsets with hippocampal depth electrodes for electrical stimulation and for reading the electroencephalogram; surgery to affix the headset securely on the mouse's skull so that it does not fall off; and key details of the electrical kindling protocol such as duration of the pulse, frequency of train, duration of train, and amount of current injected. The kindling protocol is robust in that it reliably leads to epilepsy in most VGAT-Cre mice, providing a new model to test for novel antiepileptogenic drugs.

This report describes the methods to generate a model of temporal lobe epilepsy based on the electrical kindling of transgenic VGAT-Cre mice. Kindled VGAT-Cre mice may be useful in determining what causes epilepsy and for screening novel therapies.

It was discovered that electrical kindling of VGAT-Cre mice led to the spontaneous motor and electrographic seizures. A recent paper focused on how unique ...

Implanting an Electrode Array and Optic Fiber into the Mouse Hippocampus

Transcript

Implanting an Electrode Array and Optic Fiber into the Mouse Hippocampus

Microelectrode Guided Implantation of Electrodes into the Subthalamic Nucleus of Rats for Long-term Deep Brain Stimulation

Chronic Implantation of Multiple Flexible Polymer Electrode Arrays

Preparation and Implantation of Electrodes for Electrically Kindling VGAT-Cre Mice to Generate a Model for Temporal Lobe Epilepsy