We present the construction of a 3D-printable hyperdrive with eighteen independently adjustable tetrodes. The hyperdrive is designed to record brain activity in freely behaving rats over a period of several weeks.
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Method Article
Construction of an Improved Multi-Tetrode Hyperdrive for Large-Scale Neural Recording in Behaving Rats
In This Article
Summary
Abstract
Monitoring the activity patterns of a large population of neurons over many days in awake animals is a valuable technique in the field of systems neuroscience. One key component of this technique consists of the precise placement of multiple electrodes into desired brain regions and the maintenance of their stability. Here, we describe a protocol for the construction of a 3D-printable hyperdrive, which includes eighteen independently adjustable tetrodes, and is specifically designed for in vivo extracellular neural recording in freely behaving rats. The tetrodes attached to the microdrives can either be individually advanced into multiple brain regions along the track, or can be used to place an array of electrodes into a smaller area. The multiple tetrodes allow for simultaneous examination of action potentials from dozens of individual neurons, as well as local field potentials from populations of neurons in the brain during active behavior. In addition, the design provides for simpler 3D drafting software that can easily be modified for differing experimental needs.
Introduction
In the field of systems neuroscience, scientists study the neural correlates underlying cognitive processes such as spatial navigation, memory, and decision-making. For these types of studies, it is critical to monitor the activity of many individual neurons during animal behavior. Over the past decades, two important advances have been made to meet the experimental needs for extracellular neural recording in small animals1,2,3. First was the development of the tetrode, a bundle of four microwires used to record neural activity of neurons simultaneously1
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Protocol
1. Stereolithography of 3D Models
- Use stereolithographic techniques to print the hyperdrive parts and accessories. Each hyperdrive is comprised of eighteen shuttles, eighteen shuttle bolts, and one each of all other plastic pieces (Figure 1).
NOTE: The accessories are not part of the hyperdrive but are necessary for hyperdrive construction.
2. Preparation of Accessories (Figure 2).
- Preparation of the microdrive rack (Figure 2C).
- Clean and expand the smaller through-holes and the larger ....
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Results
We used a newly built hyperdrive to obtain trial results. The drive was equipped with tetrodes constructed from ø 17 µm (0.0007"), polyimide-coated platinum-iridium (90%-10%) wire. The tips of the tetrodes were plated in platinum black solution to reduce electrode impedances to between 100 and 200 kΩ at 1 kHz. The hyperdrive was implanted 4.6 mm left of the midline and 0.5 mm anterior to the transverse sinus on the skull of a 550 g, male Long-Evans rat. Additional ground wires were connec.......
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Discussion
Here, we describe the process of constructing a newly developed hyperdrive comprised of eighteen independently movable tetrodes. The drive can be constructed from affordable parts purchased at many available hardware stores, combined with components created by stereolithographic printing. The hyperdrive can be chronically implanted onto a rat's skull using standard surgical procedures and is capable of recording extracellular neural activity while the animal performs various behavioral tasks.
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Disclosures
The authors have nothing to disclose.
Acknowledgements
We thank the Moser Lab at the Kavli Institute for Systems Neuroscience and Centre for Neural Computation, Norwegian University of Science and Technology, for the chronic neural recording procedures in rats. This work was supported by NIH grant R21 NS098146, and Human Frontier Science Program Long-Term Fellowship LT000211/2016-L to L. Lu.
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Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| Welding rod | Blue Demon | ER308L-035-01T | Stainless steel, 0.035" in diameter |
| Screw | McMaster | 91771A060 | Stainless steel, flat head, 0-80 thread, 5/8" in length |
| Screw | McMaster | 91772A051 | Stainless steel, pan head, 0-80 thread, 5/32" in length |
| Screw | McMaster | 92196A056 | Stainless steel, socket head, 0-80 thread, 5/16" in length |
| Screw | McMaster | 92196A055 | Stainless steel, socket head, 0-80 thread, 1/4" in length |
| Screw | McMaster | 95868A131 | Nylon, socket head, 2-56 thread, 3/16" in length, black |
| Screw nut | McMaster | 90730A001 | Stainless steel, narrow hex, 0-80 thread |
| Shoulder screw | McMaster | 90298A213 | Stainless steel, 8-32 thread, 3/16" in diameter, 1/4" in length |
| Cup screw | McMaster | 92313A105 | Stainless steel, 4-40 thread, 3/16" in length |
| Thumb screw | McMaster | 94323A592 | Nylon, 8-32 thread, 3/8" in length, black |
| Magnet | Apex | M3X1MMDI | Neodymium, 3 mm X 1 mm disc |
| Metal tubing | Small Parts | B00137QHNS | Stainless steel, 23 gauge, 0.0253" OD, 0.013" ID, 0.006" wall |
| Metal tubing | New England Small Tube | Custom-made | Stainless steel, 30 gauge, 0.012/0.0125" OD, 0.007/0.008" ID, full hard |
| Heat-shrink tubing | McMaster | 7856K72 | 0.09" ID before shrinking, blue |
| Silicone tubing | A-M Systems | 807300 | 0.040" ID, 0.085" OD |
| Polyimide tubing | A-M Systems | 823400 | 0.0045" ID, 0.0005" wall |
| Ground wire | A-M Systems | 791500 | 0.005" bare, 0.008" coated, half hard |
| Tetrode wire | California Fine Wire | Custom-made | 0.0007" in diameter, platinum-iridium (90%-10%), HML and VG coating |
| EIB | Neuralynx | EIB-72-QC-Large | |
| Gold pins | Neuralynx | large EIB pins | |
| Tap | Balax | 01302-000 | M1.2 thread size |
| Tap | McMaster | 2522A811 | 0-80 thread size, bottoming |
| Tap | McMaster | 2522A771 | 0-80 thread size, plug |
| Tap | McMaster | 26955A94 | 3/8"-24 thread size, bottoming |
| Tap | McMaster | 2522A713 | 2-56 thread size |
| Tap | McMaster | 2522A715 | 4-40 thread size |
| Tap | McMaster | 2522A718 | 8-32 thread size |
| Die | McMaster | 2576A457 | 3/8"-24 thread size, 1" OD |
| Drill bit | McMaster | 30585A82 | Wire gauge 65, 0.035" in diameter |
| Drill bit | McMaster | 30585A83 | Wire gauge 66, 0.033" in diameter |
| Drill bit | McMaster | 30585A87 | Wire gauge 70, 0.028" in diameter |
| Drill bit | McMaster | 30585A88 | Wire gauge 71, 0.026" in diameter |
| Drill bit | McMaster | 30585A91 | Wire gauge 73, 0.024" in diameter |
| Drill bit | McMaster | 8870A23 | 3/16" in diameter |
| Dremel disc | Wagner | 31M | Diamond coated, 22 mm in diameter, 0.17 mm in thickness |
| Steel wire | Precision Brand | 21212 | 0.012" in diameter, full hard |
| Steel wire | Precision Brand | 21007 | 0.007" in diameter, full hard |
| Steel wire | A-M Systems | 792700 | 0.003" in diameter, half hard |
| Super glue | Loctite | LT-40640 | # 406 |
| Super glue | Loctite | LT-41550 | # 415 |
| Dental acrylic powder | Teets | 223-3773 | Coral |
| Dental acrylic liquid | Teets | 223-4003 |
References
- O'Keefe, J., Recce, M. L. Phase relationship between hippocampal place units and the EEG theta rhythm. Hippocampus. 3 (3), 317-330 (1993).
- Wilson, M. A., McNaughton, B. L. Dynamics of the hippocampal ensemble code for space. Science. 261 (5124), 1055-1058 (1993).
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