Name: Micro-drive Array for Chronic in vivo Recording: Drive Fabrication (Video) | JoVE Journal
Uploaded: 2009-04-20T00:00:00.000+00:00
Duration: 14 min 3 s
Description: Learn to fabricate a lightweight micro-drive array with 21 independently adjustable screw-driven micro drives for chronic electrophysiological recordings in freely moving rats. This protocol enables precise electrode positioning.

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5 minutes

We would like to acknowledge Linus D. Sun and Jeenah Jung, who originated the use of computer-designed, 3-D printed drives in our lab for recording from mice. In addition, we would like to acknowledge all past and present Wilson Lab members for their contributions to micro-drive and tetrode technology development in the lab.

<ol>
<li>Micro-drive array overview A complete micro-drive array consists of several main components (Fig. 1):<ol>
<li>A computer designed plastic base that holds 21 independently movable micro-drives. </li>
<li>A cannula at the bottom of the base in which a set of stationary tetrode guide tubes is collected.</li>
<li>21 micro-drives that each carry one tetrode and which can be individually driven using a screw.</li>
<li>An electrode interface board for interconnection between tetrodes and pre-amplifiers.</li>
<li>A protective cone (not shown in Fig. 1) </li>
<li>In a fully assembled micro-drive array, the plastic base holds all micro-drives. Each micro-drive carries a single tetrode. The tetrode is electrically connected to the electrode interface board at the top of the micro-drive array, and passes through the stationary guide tube to exit towards the brain at the bottom of the micro-drive array. Turning the screw on each micro-drive advances or retracts the tetrode.</li>
</ol></li>
 
<li>Design of plastic base We design the base of the micro-drive assembly in a 3-D CAD software package (SolidWorks). The advantage of this in-house design process is rapid turnover and flexibility of design. In the Wilson lab we have designed many variants of this part, geared towards the specific demands of each experiment. The 3-D model file is sent to a service bureau where it is printed from a laser-curable liquid resin using stereolithography. Turnaround time is as little as 2 days. The resulting part is lightweight, reusable, and can be machined to hold a thread. In this protocol we will use a drive base that is designed with a single recording site and which holds 21 micro-drives. The SolidWorks design file is made available upon request.</li>
 
<li>Preparation of plastic base The plastic base is processed to accommodate the micro-drives and the screws to attach the electrode interface board and the protective cone. It is not possible to reliably print smooth through holes in the plastic base, so we design undersized holes, then expand them by drilling. Carefully align the drill bit with the axis of the existing hole before drilling at very low speed. A variable speed/torque hand drill works well for this task.<ol>
<li>Drill the 21 pilot holes for the micro-drive screws (the outer ring) using a #61 bit.</li>
<li>Drill the 21 holes for the the micro-drive support tubes (the inner ring) using a #65 bit. </li>
<li>Drill the holes that will be used to attach the electrode interface board and protective cone using a 1.55 mm bit. </li>
<li>Press fit a sleeve (5 mm long 20 Ga thin wall stainless steel tubing) into each of the inner ring of holes using a pair of tweezers or a pair of pliers so that it is flush with the plastic base. The sleeves ensure smooth movement of the micro-drive support tubes. Next, all holes that will hold screws are tapped. In printed plastics, thread-forming taps result in more durable threads than typical thread-cutting taps. This style of tap requires larger pilot holes. Using a hand-held pin vise to hold the tap:</li>
 
<li>Tap the holes for the micro-drive screws using a tap that matches the screw size being used (M1.2x0.25) and a dry lubricant. To help align the tap with the pilot hole, insert a length of 23 Ga tubing into the sleeve next to it.</li>
<li>Our plastic base design features a tap starter for each micro-drive screw hole to make sure the initial threads are not damaged during the threading process. After all holes are threaded, these tap starters can be easily snapped off using a razor blade.</li>
<li>Tap the holes that will hold the screws for the electrode interface board and the protective cone using a 1-72 tap. </li>
</ol></li>
 
<li>Insertion of electrode guide tubes <ol> 
<li>To make the cannula that holds all the stationary electrode guide tubes, cut a 1.5cm-long piece of 13 Ga stainless steel tubing and roughen the surface with a dremel grinding wheel to enhance adhesion by the dental acrylic.</li>
<li>Insert this cannula into the hole at the bottom of the plastic base, verify that it is co-linear with the vertical axis of the drive, and secure it with dental acrylic or epoxy. Leave 5 to 7 mm of the cannula exposed to facilitate surgical implantation.</li>
<li>Cut 21 stationary electrode guide tubes (flexible polyimide tubing, inner diameter: 0.0071", outer diameter: 0.0116") with a razor blade to a length of 6  cm. </li>
<li>Feed the guide tubes one at a time into the sleeves at the top of the drive base and all the way through the collector cannula at the bottom. Visually check for kinks or excessive bending and replace tubes if necessary. To facilitate the insertion and parallel alignment of the tetrode guide tubes, one can start with first feeding the entire bundle of 21 guide tubes up into the collector cannula from below. Then, one at a time, remove a guide tube from the bundle and feed it from the top of the plastic base through the hole that it left behind in the bundle. </li>
<li>Push the guide tubes down until they extend only 1-2 mm from the top of the plastic base. Apply a small amount of thin cyanoacrylate glue to the tubes as they exit the collector cannula, being careful not to let any glue flow up into the end of the guide tubes.</li>
<li>Use a fresh razor blade to cut off the excess from the bundle of guide tubes at the bottom of the collector cannula.</li>
 </ol> </li>
<li>Fabrication of micro-drives Each micro-drive consists of a custom-machined screw and a hollow support tube (Fig. 2). The screw and support tube are attached together such that a lip on the screw is embedded in acrylic, leaving the screw to rotate freely (Fig. 2B). The screw is threaded into the plastic base, and the support tube is then driven up or down when the screw is turned, advancing or retracting the tetrode that it carries. For ease of adjustment on the behaving animal, the head of the screw is in the shape of a half-cylinder. Make a custom screwdriver for this screw: <ol>
<li>Cut 5 cm of 15 Ga stainless steel tubing.</li>
<li>Take one of the custom screws and grind off the protruding lip.</li>
<li>Insert the screw into the tubing until the top of the screw is flush with the end of the tubing. </li>
<li>Crush the tubing around the screw threads repeatedly with a pair of locking pliers so that the screw cannot rotate relative to the cannula. </li>
<li>Use a pin vise to hold the custom screw driver. To fabricate the micro-drives we use a 3-D printed plastic mold with small wells (3 mm x 5 mm, 2 mm deep). Each well has two holes in the bottom surface, spaced 2 mm apart, for the support tube and the screw. Alternatively, molds can be fabricated from an engineering plastic like Delrin, using a drill press to create the well and holes.</li>
 
<li>Prepare the mold by clearing the hole for the support cannula using a 23 Ga needle and tapping the hole for the screw as described for the plastic base, above.</li>
<li>Line the inside of the well with teflon lubricant or a thin film of petroleum jelly to allow for release of the cured dental acrylic from the mold.. </li>
<li>Apply teflon lubricant to a screw and insert it into the mold using the custom made screwdriver until the threads are just below the bottom of the well. </li>
<li>Roughen the top 2-3 mm of a 14 mm-long support tube (23 Ga stainless steel tubing) with a  grinding wheel to enhance adhesion of the dental acrylic. Insert it into the mold until the top of the cannula is halfway between the top of the well and the top of the screw.</li>
<li>Pour dental acrylic into the well. Agitating motion is used to ensure that the dental acrylic flows into all the spaces around the screw and support tube. Remove any air bubbles with a small needle. </li>
<li>Wait until the dental acrylic is completely cured (15-30 minutes) and then remove the micro-drive from the mold by turning the screw counter-clock wise. </li>
<li>It is important to do a quality check of the micro-drives. Inspect the cured dental acrylic for cracks and/or air bubbles, which are usually caused by dental acrylic that was too thick or too thin. Also, make sure the screw and the support tube are parallel to each other and that the screw turns smoothly. Screws and support tubes of micro-drives that do not meet these criteria can be cracked free from the dental acrylic and recycled. </li>
<li>Repeat steps 5.6 through 5.11 until you have 21 micro-drives. </li>
</ol></li>
 
<li>Final assembly of micro-drive array<ol> 
<li>Lower each micro-drive into the plastic drive base. Each micro-drive support tube should move smoothly both inside its sleeve and over its stationary guide tube. Check to make sure that the guide tubes do not buckle as the micro-drive is being lowered. </li>
<li>With the micro-drives completely lowered, add a thin layer of dental acrylic to the interior of the drive base to fix the electrode guide tubes in place. </li>
<li>Note that failure to lower the micro drives all the way before adding the dental acrylic will result in wicking of the acrylic all the way up the sleeves and obstruction of micro-drive movement. </li>
<li>Label the micro-drives 1-21. </li>
<li>Turn the drive array upside down and take a picture of the bundle of guide tubes. This picture will be used to map the location of the guide tube corresponding to each micro-drive. </li>
<li>Raise all the micro-drives by several mm.</li>
<li>Insert a polyimide carrier tube (0.005") into each guide tube from the bottom of the drive base. Let the carrier tube extend 1-2 mm from the top of the fully lowered micro-drive and and record on the photograph the identity of the corresponding micro-drive.</li>
<li>Glue the carrier tube to the micro-drive support tube using 5-minute epoxy or cyanoacrylate glue. Note that glue or epoxy that is too thin will flow down the support cannula and obstruct free motion of the micro-drive or, worse, fix it to the guide cannula. If this happens, that particular micro-drive unit can not be used. </li>
<li>Fully lower all the micro-drives. Cut all the carrier tubes off flush at the bottom of the collector cannula using a fresh razor blade.</li>
<li>Finally, mount the Neuralynx electrode interface board to the drive base using two screws (size: 1-72, length: 3/16"). </li>
</ol></li>
</ol>
At this point the drive array is ready to be loaded with tetrodes. Fabrication of tetrodes, how to load them into the micro-drives, and how to prepare the drive array for surgical implantation are the subjects of a subsequent video article.
<img src="/files/ftp_upload/1094/Figure1.png" alt="Neuroscience diagram with electrode interface, micro-drives, plastic base, collector cannula setup." data-altupdatedat="1787630408000" data-alt="Figure 1"> Figure 1. Model of finished micro-drive array. A micro-drive array consists of several major components: a plastic drive base; a collector cannula from which the tetrodes enter the brain; 21 micro-drives that each drive a single tetrode; an electrode interface board that connects to pre-amplifiers.
<img src="/files/ftp_upload/1094/Figure2.png" alt="Static equilibrium custom screw design; technical diagram with measurements and labeled components." data-altupdatedat="1787630408000" data-alt="Figure 2"> Figure 2. Custom micro-drive screws. A. Technical drawings of the custom screw design. The screw features a threaded part (M1.2x0.25; 1.2 mm diameter, 0.25 mm / turn), a half-cylinder head that matches our custom made screw driver and a smooth part with lip (see detail). B. Model of complete micro-drive. The support tube and custom screw are connected with dental cement. The lip on the screw is embedded in the dental cement and allows for free rotation while driving the support tube up or down.
Additional Files
We designed the printed drive base, the protective cone and the mold for construction of the micro-drives in SolidWorks 2008 3D CAD software:
<ul style="list-style-type:none;">
<li>Download the file:<a href="https://www.jove.com/files/ftp_upload/1094/DriveBase.SLDPRT"> DriveBase.sldprt</a> which contains models of the drive base and protective cone and cap.</li>
<li>Download the file:<a href="https://www.jove.com/files/ftp_upload/1094/MicroDriveMold.SLDPRT"> MicroDriveMold.sldprt</a> which contains model of the micro-drive mold</li>
</ul>
The 3D printing service bureau can not handle native Solidworks files directly, but rather requires the design files in stereolithography CAD format (STL). For people who do not have access to Solidworks software, but still would like to use the printed parts used in the video article we include the designs in STL format as well:
<ul style="list-style-type:none;">
<li>Download the file:<a href="https://www.jove.com/files/ftp_upload/1094/DriveBase.STL"> DriveBase.stl</a> which contains model of drive base</li>
<li>Download the file:<a href="https://www.jove.com/files/ftp_upload/1094/MicroDriveMold.STL"> MicroDriveMold.stl</a> which contains model of micro-drive mold</li>
<li>Download the file:<a href="https://www.jove.com/files/ftp_upload/1094/ProtectionCap.STL"> ProtectionCap.stl</a> which contains model of cap for protective cone</li>
<li>Download the file:<a href="https://www.jove.com/files/ftp_upload/1094/ProtectionCone.STL"> ProtectionCone.stl</a> which contains model of protective cone</li>
</ul>
Fixes to these files, and additional models, are tracked on <a href="https://github.com/wilsonlab/CAD-Files/tree/master/stl">github</a>.

<ol><li>Yamamoto, J., Wilson, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Large-scale+chronically+implantable+precision+motorized+microdrive+array+for+freely+behaving+animals%5BTitle%5D)+AND+%22J.+Neurophysiol%22%5BJournal%5D)">Large-scale chronically implantable precision motorized microdrive array for freely behaving animals.</a> J. Neurophysiol. 100 (4), 2430-2440 (2008).</li>
</ol>

This protocol describes the general features of the micro-drive building process. It has been successfully modified to produce drive arrays with multiple recording targets or smaller arrays for recordings in mice. In addition to recording from the hippocampus, many researchers use these drives to target cortical and sub-cortical structures. The use of longer screws may be required in order to record from deeper brain structures. With extensive modification to the drive base, motorized drives my be used in lieu of manuall...

<table><tbody><tr><td>3D-printed plastic parts</td><td>Material</td><td>American Precision Prototyping (www.approto.com)</td><td>&amp;nbsp;</td></tr><tr><td>stainless steel tubing</td><td>Material</td><td>Small Parts (www.smallparts.com)</td><td>&amp;nbsp;</td></tr><tr><td>Dental cement powder</td><td>Material</td><td>A-M Systems (www.a-msystems.com)</td><td>525000</td></tr><tr><td>Dental cement solvent</td><td>Material</td><td>A-M Systems</td><td>526000</td></tr><tr><td>Electrode interface board</td><td>Material</td><td>Neuralynx (www.neuralynx.com)</td><td>EIB-81</td></tr><tr><td>micro-drive screws</td><td>Material</td><td>Advanced Machining and Tooling (www.amtmfg.com)</td><td>&amp;nbsp;</td></tr><tr><td>&amp;rsquo;Tap-Ease&amp;rsquo; tapping lubricant </td><td>Tool</td><td>AGS Company</td><td>TA-2</td></tr><tr><td>Polyimide tubing </td><td>Material</td><td>IWG High Performance Conductors (www.iwghpc.com)</td><td>&amp;nbsp;</td></tr><tr><td>Cordless drill/driver </td><td>Tool</td><td>DeWalt (www.dewalt.com)</td><td>DC750KA </td></tr><tr><td>Variable-Speed Rotary Tool Kit with Flex-Shaft </td><td>Tool</td><td>Dremel (www.dremel.com)</td><td>3956-02</td></tr><tr><td>Razor blades </td><td>Tool</td><td>VWR (www.vwr.com)</td><td>55411-050</td></tr><tr><td>Watch glass </td><td>Tool</td><td>VWR</td><td>66112-107</td></tr><tr><td>Tap for custom screws</td><td>Tool</td><td>Balax</td><td>01302</td></tr><tr><td>Taps</td><td>Tool</td><td>Small Parts</td><td>HSBT-0172, HSBT-0080 </td></tr><tr><td>Pin vise</td><td>Tool</td><td>Vargus</td><td>3SHC1--I </td></tr><tr><td>Drill bits</td><td>Tool</td><td>Small Parts</td><td>&amp;nbsp;</td></tr><tr><td>Benchtop vise</td><td>Tool</td><td>Panavise</td><td>301</td></tr><tr><td>No.2 Dumont forceps</td><td>Tool</td><td>Stoelting (www.stoeltingco.com)</td><td>52100-27</td></tr><tr><td>5-minute epoxy</td><td>Tool</td><td>Allied Electronics (www.alliedelec.com)</td><td>&amp;nbsp;</td></tr><tr><td>Accu-Tek Carbofib Tip Tweezers</td><td>Tool</td><td>Aven (www.aveninc.com)</td><td>18768 (Pattern 304)</td></tr><tr><td>Micro Dissecting Scissors</td><td>Tool</td><td>Biomedical Research Instruments (www.biomedinstr.com)</td><td>25-1000</td></tr><tr><td>Xcelite 378M Pliers</td><td>Tool</td><td>Newark</td><td>96F8903</td></tr><tr><td>mini pin vise</td><td>Tool</td><td>MSC Industrial Supply (www.mscdirect.com)</td><td>00920314 </td></tr></tbody></table>

micro-drive array for chronic in vivo recording: drive fabrication

Micro-drive Array for Chronic in vivo Recording: Drive Fabrication

Chronic recording of large populations of neurons is a valuable technique for studying the function of neuronal circuits in awake behaving rats. Lightweight recording devices carrying a high density array of tetrodes allow for the simultaneous monitoring of the activity of tens to hundreds of individual neurons. Here we describe a protocol for the fabrication of a micro-drive array with twenty one independently movable micro-drives. This device has been used successfully to record from hippocampal and cortical neurons in our lab. We show how to prepare a custom designed, 3-D printed plastic base that will hold the micro-drives. We demonstrate how to construct the individual micro-drives and how to assemble the complete micro-drive array. Further preparation of the drive array for surgical implantation, such as the fabrication of tetrodes, loading of tetrodes into the drive array and gold-plating, is covered in a subsequent video article.

In this protocol we demonstrate how to fabricate a micro-drive array for chronic electrophysiological recordings in rats.

Chronic recording of large populations of neurons is a valuable technique for studying the function of neuronal circuits in awake behaving rats. ...

This video will cover the assembly of a lightweight micro drive array with 21 independently adjustable screw driven micro drives. Each micro drive controls the recording position of a single electrode. The micro drives are mounted in a computer designed plastic base that stabilizes them relative to the skull of the moving animal and collects the electrodes into a densely packed pattern that can pass through a small craniotomy into the brain.The base also supports an electrode interface board for the connection to the recording instruments, which allows for the animal to be conveniently plugged in and unplugged at the beginning and end of an experiment. A plastic cone attached to the base protects the micro drives and electrodes from the elements in the rat cage. Hi, I'm Faia Postman from the laboratory of Matt Wilson in the PIKA Institute for Learning and Memory at the Massachusetts Institute of Technology.Today we'll show you a protocol for how to fabricate one of those micro dive arrays. In our laboratory, we use those micro dive arrays to record from a large population of neurons in the brain of rats, for example, from the cortex or hippocampus. First, we will show you how we designed our micro dive array.Then we will head over to the workshop where Steve and Stewart will show us how to process the raw materials and how to assemble them into a fully functional device. So let's get started. The plastic base is designed using computer rated design software and is manufactured using an inexpensive 3D printing process.We also model all the other components of the micro drive array. This allows us to carefully control the size and weight of the finished drive. At the top of the plastic base are two rings of holes that will accept the individual micro drives.The 3D model is sent to a service bureau that builds the design from a laser curable resin using stereo lithography. That should only take a few days and the resulting part is lightweight and reusable. Once the part arrives from the service bureau, we need to prepare it for use.So let's head over to the workshop. The 3D printing process cannot reliably print small holes, so we specify smaller diameter holes in our models. Then drill and tap the holes to the required size in the workshop.Three different size drill bits are used to prepare the plastic base, a number 61 bit, a number 65 bit, and a 1.55 millimeter bit in the outer ring of the base. Use a hand drill with a number 61 bit at very low speeds to prepare the pilot holes where later the micro drive screws will be inserted. Next, prepare the holes for the micro drive support tubes in the entering in the base by drilling out these holes with a number 65 bit.Using the larger 1.55 millimeter bit, drill out the holes that will attach the base to the electrode interface board and protective cone. To ensure smooth movement in the micro drive, insert a stainless steel sleeve into the inner ring of holes. Each sleeve should be press fit with a pair of pliers until it is flushed with the top of the base.The screw pilot holes now need to be threaded. Use a pin vice to hold the tap and apply a dry lubricant before tapping. Align the tap and it's all by making sure it is parallel to a 23 gauge tube you temporarily insert into the neighboring sleeve.The holes that hold the interface board and the protective cone need to be threaded. Hand tap these holes the same way. The plastic based design features a tap starter for each screw pilot hole to make sure the initial threads are not damaged during the threading process.After all pilot holes are threaded. These tap starters can be easily snapped off using a razor blade. The electrodes are guided toward a single site at the bottom of the drive by a number of electro guide tubes.First, we need to make the collector cannula that will hold all the electro guide tubes. The collector cannula is made from a 1.5 centimeter long piece of stainless steel tube. The collector cannula will be held in with dental cement.So to enhance adhesion carefully roughen the tube using a Dremel grinding wheel, insert this cannula into the bottom of the plastic base. Position it so that five to seven millimeters of the cannula remains outside of the micro drive array. To facilitate surgical implantation, attach the collector cannula to the bottom of the plastic base.With dental acrylic, allow it to cure for at least 15 minutes. Now, prepare the guide tubes by cutting 21 pieces of polyamide with a razor blade. Begin this step by feeding all 21 guide tubes into the collector cannula at the bottom of the drive base.This will make sure that the tubes are all parallel to one another. If tubes in the bundle are too loose or tight, you can start with fewer tubes or add extra tubes as needed. Now, remove each guide tube one at a time and feed it into one of the sleeves at the top of the drive.Pass the tube down through the gap at left behind in the bundle of tubes. Inspect guide tubes for kinks or tight bends and replace as needed. Adjust each guide tubes position so it extends one to two millimeters from the top of the sleeve.Now add a small drop of thin sano acro lake glue to the bottom of the collector cannula. Be very careful not to let the glue flow into the guide tubes. Next, use a fresh razor blade to cut off the bundle of any excess tubing at the bottom of the collector cannula.Verify under a stereoscope that the tubes are neatly cut and flush with the cannula. Each electrode is advanced by its own micro drive, so we need to make 21 micro drives and then insert them into the plastic base. Each micro drive consists of a custom screw and a hollow support tube, which are attached to each other.With dental acrylic, the electrode will pass through the support tube. The screw features a non threaded part with a small lip that is embedded in the dental acrylic and allows the screw to turn freely in this way. As the screw is turned into the plastic base, it advances or retracts the electrode.The head of the screw is shaped like a half cylinder. Before we can make the micro drives, we need to make a screwdriver to turn our custom screws. Our makeshift screwdriver is constructed by taking a custom screw and completely grinding down the lip that surrounds the half cylinder head.Insert the screw head out into a five centimeter long 15 gauge tube until it is fully encased. Now, crush the tube around the threads of the screw, securing it in the tube and preventing it from turning. Attach a mini pin vice to act as a handle in voila a screwdriver.The micro drive is made by molding dental acrylic around the screw and the support tube. The molds we use are 3D printed plastic just like the plastic base and have holes in the bottom that keep the screw and the support post aligned as we pour the acrylic into the mold. First, we need to prepare the mold clear out the support tube hole using a 23 gauge needle, clear out the screw hole and create threads using a tap.This is the same procedure we just used on the plastic base. Now the mold is ready to use to make micro drives. Line the mold with a Teflon based lubricant to prevent the dental acrylic from sticking to the mold.Scuff the top two to three millimeters of a 14 millimeter long 23 gauge stainless steel support post with a grinding wheel so that it will be firmly secured in the depth of acrylic. Insert the support post into the smaller hole of the mold so that the top of the post is above the top of the.Well. Apply a thin film of Teflon based lubricant to a screw and insert it into the threaded hole until the threads are just below the bottom of the well.Now mix up some dental acrylic and poured into the mold. Make sure it gets into all the nooks and crannies. A needle can help dislodge air bubbles once the acrylic is hardened.You can remove the micro drive by backing out the screw. Do a strict quality check. There should be no cracks or bubbles in the acrylic.The post and screws should be parallel and unable to move sideways. The screws should turn smoothly, but with no play any bad micro drives should be broken down in the parts reused. Repeat this process until you have 21 good micro drives.If your mold has multiple wells, then you can make the micro drives and batches to save time. Carefully align each micro drive with a pair of holes in the plastic base. Slip the micro drive support tube over the poly me guide tube and into the metal sleeve while using the screwdriver to advance the micro drive screw.This can be tricky. Keep your eye on the center of the base to make sure that the guide tube does not get caught in buckle as the micro drive is lowered. Once all the micro drive are in place and fully lowered, a small amount of acrylic is dropped into the center of the drive to lock the bouquet of guide tubes in place.Allow the acrylic to cure for 15 minutes. Once the acrylic is dry, to retract each micro drive about three millimeters, create a top-down view schematic of the micro drives and give each micro drive a unique name or number. Now looking in the stereoscope, flip the drive upside down and take a picture of the bottom of the collector cannula and guide tubes.Make a printout of the picture that can be used as a reference in the following steps. Next with the drive upside down, insert a narrow polyamide carrier tube into each guide tube until it comes out the top of a micro drive. Note on the photograph which guide tube corresponds to which micro drive.The carrier tube will later protect and support the delicate electrode wires. It passes through the micro drive. Extend each carrier tube until it is one centimeter above the top of the micro drive support tube, and then glue the carrier tube to the support tube with five minute epoxy or thick sano acro lake glue.Be very careful with this step. If glue drips down the inside of the support tube, it can bind the support tube to the stationary guide tube ruining that micro drive. This is the reason that we raise the micro drives before inserting the carrier tubes.Once all the carrier tubes are glued in place, fully lower the micro drives again and cut all the carrier tubes off flush at the bottom of the drive using a fresh razor blade. Next, cut the carrier tubes one to two millimeters above the top of the micro drive using sharp scissors. Finally place the electrode interface board on top of the drive base and mount it with two screws.At this point, the drive array is ready to be loaded with electrodes and our experiments. We typically use four channel microwire electrodes called tetros, but any type of electrode can be used. Fabrication of teros, how to load them into the micro drives and how to prepare the drive array for surgical implantation are covered in other Joe videos.This protocol can be followed directly or modified to meet your needs. For example, some researchers will require longer screws to record from deeper brain structures. Others may wish to design a drive that targets more than one brain location.The design can also be miniaturized for use in smaller animals like mice with slightly more modification, motorized micro drives may be used, which allow remote adjustment of the electrode positions. We just showed you how to design and fabricate a micro drive array that can be implanted onto the head of a rat and allows us to record from large populations of neurons while the animal is really moving. When doing this procedure, it's important to remember to carefully thread the holes in the plastic base so that the micro drive screws do not slip.Perform a rigorous quality check of the fabricated micro drives. Make sure the screw and the support tube are parallel and that the screw turns smoothly without play. Be careful when using glue or dental acrylic to not accidentally clog any of the tubing.Finally, remember that to complete the MyDrive array and before doing the surgery, you will have to fabricate tetros and low dose into the drive. This is covered in another job video article. So that's it.Thank you for watching and good luck with your experiments.

micro-drive-array-for-chronic-in-vivo-recording-drive-fabrication

Research

JoVE Journal

Biology

In this protocol we demonstrate how to fabricate and condition tetrodes for use with a micro-drive array, which was designed for chronic electrophysiological recordings in rats.  In addition, we illustrate the final stages of micro-drive array construction, which includes installing ground wires and a protective cone.

Micro-drive Array for Chronic in vivo Recording: Tetrode Assembly

The design, fabrication and assembly of an ultra-light motorized microdrive is described.  The device provides a cost-effective and easy-to-use solution for chronic recordings of single units in small behaving animals.

Design and Assembly of an Ultra-light Motorized Microdrive for Chronic Neural Recordings in Small Animals

The video demonstrates simultaneous electrophysiological recording from multiple brain regions in a rat using an integrative micro-drive array. Recording electrodes are placed in the olfactory bulb, reference electrodes in the frontal cortex, and micro-drive array electrodes in the hippocampus. The rat is allowed to forage freely, and simultaneous recording from all the implanted electrodes is recorded using the array.

A Micro-drive Array Method for Electrophysiological Recording from Multiple Brain Regions

The design and assembly of microdrives for in vivo electrophysiological recordings of brain signals from the mouse is described. By attaching microelectrode bundles to sturdy driveable carriers, these techniques allow for long-term and stable neural recordings. The lightweight design allows for unrestricted behavioral performance by the animal following drive implantation.

Construction of Microdrive Arrays for Chronic Neural Recordings in Awake Behaving Mice

Understanding the neural substrates of behavior requires brain circuit ensemble recording. Because of its genetic tractability, the mouse offers a model for circuit dissection and disease mimicry. Here, a method of designing and fabricating miniaturized probes is described that is suitable for targeting deep brain structure in the mouse.

Design and Fabrication of Ultralight Weight, Adjustable Multi-electrode Probes for Electrophysiological Recordings in Mice

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.

Chronic Implantation of Multiple Flexible Polymer Electrode Arrays

This protocol describes the construction of a hybrid microdrive array that allows implantation of nine independently adjustable tetrodes and one adjustable opto-silicon probe in two brain regions in freely moving mice. Also demonstrated is a method for safely recovering and reusing the opto-silicon probe for multiple purposes.

Hybrid Microdrive System with Recoverable Opto-Silicon Probe and Tetrode for Dual-Site High Density Recording in Freely Moving Mice

We describe here a method for fabricating Ti3C2 MXene microelectrode arrays and utilizing them for in vivo neural recording.

Fabrication of Ti3C2 MXene Microelectrode Arrays for In Vivo Neural Recording

This protocol describes a procedure for constructing carbon fiber microelectrode arrays for chronic and acute in vivo electrophysiological recordings in mouse (Mus musculus) and ferret (Mustela putorius furo) from multiple brain regions. Each step, following the purchase of raw carbon fibers to microelectrode array implantation, is described in detail, with emphasis on microelectrode array construction.

Construction and Implementation of Carbon Fiber Microelectrode Arrays for Chronic and Acute In Vivo Recordings

Here, we describe a micro-drive design, surgical implantation procedure, and post-surgery recovery strategy that allow for chronic field and single-unit recordings from multiple brain regions simultaneously in juvenile and adolescent mice across a critical developmental window from postnatal day 20 (p20) to postnatal day 60 (p60) and beyond.

A Lightweight Drive Implant for Chronic Tetrode Recordings in Juvenile Mice

Here, we introduce a lightweight, cost-effective probe implant system for chronic electrophysiology in rodents optimized for ease of use, probe recovery, experimental versatility, and compatibility with behavior.

The DREAM Implant: A Lightweight, Modular, and Cost-Effective Implant System for Chronic Electrophysiology in Head-Fixed and Freely Behaving Mice

Learn to fabricate a lightweight micro-drive array with 21 independently adjustable screw-driven micro drives for chronic electrophysiological recordings in freely moving rats. This protocol enables precise electrode positioning.

Micro-drive Array for Chronic in vivo Recording: Drive Fabrication

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