The authors would like to thank Angela Gomez Fonseca for the inspiration to develop the drive and all the students who ran pilot experiments with the animals, Milan Bogers, Floor van Ravenswoud, and Eva Severijnen. This work was supported by the Dutch Research Council (NWO; Crossover Program 17619 &#34;INTENSE&#34;).

Open&#45;Source Implant for Multi&#45;Region Electrophysiological Monitoring in Rats

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TS and PvH are employees of 3Dneuro, Nijmegen, The Netherlands. 3Dneuro co-developed and produces the TD Drive.

Presented in this article is an adaptable implant for bilateral, symmetric multi-area wire electrode recordings for freely-moving rats.
The ability to easily adjust the implant by changing predefined parameters was one of the motivations for the creation of the TD Drive. While aiming to maximize the flexibility for changing parameters, inherent constraints in the relations between them necessarily impose limits to this adaptability. No limits are set by default for the anteroposterior parameters, with these coordinates instead being governed by logical inter-site interactions and the overall size of the drive body. The parameters controlling the mediolateral coordinates of all recording sites are subject to manually imposed limits (see Table 1). Underlying the many parametric options are numerous interactions between the design features. These interactions can become disjointed under certain conditions. In an ideal situation, all possible combinations of parameter values are valid. However, with the more complex design of the TD Drive, it was opted to limit the mediolateral coordinates to within the tested range. Choosing coordinates outside the tested limits is, in principle, possible. However, making such changes is not recommended as the integrity of the design can become compromised, and restoring it while maintaining the out-of-limit coordinates might require CAD modeling experience. This is an inherent result of the trade-off between ease of drive production and flexibility - larger degrees of freedom do make the parametric definition of the drive more complex and can result in overly fine-grained, undesired outcomes (for example, the need to produce different EIBs for small changes in the drive design).
The parameter choices made in this manifestation of the TD Drive are guided by the preferences of the current experimenters. It was opted, for example, to increase the height of the TD Drive&#39;s pedestals, improving ease of implantation during surgery at the cost of a slightly higher final implant. However, the implant is still much smaller than drives with individually moveable tetrodes and was well-accepted by the animals. The two pedestals used to anchor the drive (&#34;c&#34; in Figure 2E) are deliberately placed in the center plane, parallel to the midline suture of the rat&#39;s skull. This limits recording locations to mediolateral coordinates &#62; 0.75 mm. Often, the presence of the sagittal sinus below the midline imposes a similar limit for craniotomies anatomically. The current design of the TD Drive has been created in Autodesk Fusion. While it is one of the most advanced programs for parametric 3D computer-aided design and, at the time of publication, does provide a free license for academic use, the commercial and cloud-based nature of the program does pose a risk for the free availability of the design. Therefore, porting the design to a true open-source parametric CAD software21, such as FreeCAD, might be necessary for a future iteration.
The surgery for the TD Drive can be performed in 2-3 h. The target locations of the wire are marked stereotactically (PFC +3.5AP next to the midline, HPC -3.8AP -/+ 2.5 ML, RSC -5.8 next to the midline), and the screw electrodes, GND, and additional skull screws for stability are placed relative to those locations. While the TD Drive stencil does provide stereotactic locations, imprecisions in the placement of the polyimide tube and the use of less stiff tubing material can introduce small variations in the position of the electrodes. Therefore, it is recommended to drill small craniotomies (instead of guide tube-sized 0.5 mm burr holes) to account for this variability. In this surgery, a single, larger craniotomy for the RSC and HPC targets is drilled. For PFC and RSC, it was chosen to have wire bundles implanted at a fixed depth. The PFC bundle had wires targeted at two different depths to record from the prelimbic as well as the anterior cingulate cortex. The HPC bundles were movable and were built with 3 wires at varying heights to facilitate reaching the Ca1 pyramidal layer as well as the stratum radiatum. The last, shorter wire allowed recording from the PPC. We achieved the best results for targeting the hippocampal Ca1 when the longest electrode wire was moved to the target depth (2 mm ventrally from the brain surface) during surgery time, with only small adjustments in the two weeks after surgery during live-signal checks to accommodate for individual variances and brain swelling after surgery.
A problem with large implants, such as tetrode hyperdrives, in rats, is the chance of the implant stability degrading and animals losing the implant. For the TD Drive, individual failures were observed due to degradation of implant stability after 2 months (3 out of 16 animals). Therefore, the TD Drive is recommended for experiments with an intended maximum duration of 8 weeks. We show that for this time period, the signal is stable - even the precise hippocampal pyramidal layer recordings - and there is no systematic drift or significant wobble affecting the LFP recordings. One factor in achieving this long-term stability is the use of multiple skull screws (see Figure 3A). In certain situations, the amount of used skull anchoring screws can increase the risk of infections22. However, this is likely mostly relevant in head-fixed rats, where the repeated stress of the head fixation on the headplate and connected anchoring screws can result in degradation of the implant that facilitates infections. Another factor that increases the risk of implant failure (and can induce discomfort in behaving animals) is the weight of the implant. A complete TD drive implant with anchoring screws and dental cement weighs around 7 g, with the 3D printed parts and EIB accounting for approximately half of the weight. Due to the low weight of the TD drive (less than 1/3 of other large tetrode hyperdrives), excessive implant weight is unlikely to be a significant factor for failures of the TD drive. Generally, the main factor for stable, infection-free implants is a sterile surgery procedure and good adhesion of the dental cement that is coating the implant to the implant, anchoring screws, and skull23. We only evaluated the TD Drive for the recording of local field potentials and did not attempt to acquire single-unit activity. While we expect the implant to be generally stable enough to do so, following the same units within and between sessions might require optimization of the shuttle stability, for example, by optimizing the shuttle guide rail (&#34;b&#34; in Figure 2E). The addition of moveable shuttles to the other recording sites would allow for additional use of moveable wire electrodes, which are the preferred way of ensuring better long-term signal quality in unit recordings.
With a total assembly time of around 3 h and surgery time of around 2-3 h, the TD Drive offers a compromise between tetrode hyperdrives and simpler, less adjustable multi-wire implants24. With the chosen targets, recordings from 10 brain areas with 6 bundles were achieved. Compared to other implants for non-moveable wire bundles, the symmetric placement of recording sites yields another advantage: if lateralization is not relevant, simultaneously implanting wires in both hemispheres doubles the chance of hitting the correct target and the data yield per animal. In the pilot, 4 out of 8 animals had all 5 target sites (PFC including prelimbic (PRL) and anterior cingulate (ACC) cortex, RSC, PPC, and Ca1 pyramidal layer of HPC) targeted correctly bilaterally, but 7 out of 8 had at least each brain area on one side recorded. Thus, this drive is advisable for those who want a quick and easy-build solution to record LFP that can be applied by less experienced researchers, especially when higher animal numbers are needed, such as in sleep studies. With many high-end tetrode hyperdrives that would allow for the recording of individual neuronal activity, even very skilled and experienced researchers can only build and implant 2-6 implants per year of which many will not successfully reach any brain area of interest. It takes many years of training to achieve higher success rates, and even then, the number of animals that can be recorded efficiently remains low.
In summary, the TD Drive presents an easy and fast-to-build wire drive with 6 bundles that can be easily adapted to contain different recording sites and other implants such as cannulas and fibers.

The multi-area nature of brain interactions during wake and sleep makes it difficult to exhaustively study the ongoing physiological processes. While approaches such as functional MRI (fMRI) and functional ultrasound (fUS) allow sampling of brain activity from whole brains1,2, they exploit neurovascular coupling to infer brain activity from hemodynamic activity, limiting their temporal resolution2. In addition, fMRI requires the placement of the research subject in an MRI scanner, prohibiting experiments with freely moving animals. Optical imaging of calcium dynamics with single or multiphoton imaging enables cell type-specific recordings of hundreds of neurons simultaneously3. However, head-mounted microscopes such as the Miniscope3, which do allow freely moving behavior, are usually limited to imaging superficial cortical areas in intact brains4. While the diameter of their field of view on the cortex can be in the order of 1 mm, the space requirements of these head-mounted microscopes can make it difficult to target several, especially adjacent, areas. Therefore, to capture multi-area brain dynamics in wake and sleep accurately, extracellular electrophysiology, recorded with electrodes implanted in the brain areas of interest, is one of the methods of choice due to its high temporal resolution and spatial precision5. In addition, it allows the characterization of sleep dynamics in animals compatible with analyses obtained from human EEG, increasing the translational value of this method6.
Classically, studies recording brain activity with extracellular electrodes have employed individual wire electrodes or electrode bundles, such as tetrodes7. State-of-the-art probes such as the Neuropixels probe8 allow targeting several areas simultaneously, given that they are aligned on an axis that allows implanting the probe along that axis without impairing the animal. However, accurate simultaneous recordings of multiple, spatially separated areas still remain challenging, with existing methods being either costly or time-intensive.
In recent years, additive manufacturing methods such as stereolithography have become broadly available. This allowed researchers to develop novel electrode implants that were adaptable to their experimental requirements9, for example, simplified repeatable targeting of multiple brain areas. Frequently, these implant designs are also shared with the academic community as open-source hardware, allowing other researchers to adapt them to their own purposes. The degree of adaptability of specific implants varies both as a result of how the implant is designed and how it is shared. Parametric modeling10 is a popular approach in computer-aided design, in which different components of the design are linked by interdependent parameters and a defined design history. Implementing a parametric approach for designing implants increases their reusability and adaptability10, as changing individual parameters automatically updates the complete designs without the need for complex re-modeling of the design. A consequential necessity is that the design itself is shared in an editable format that preserves the parametric relationships and design history. File formats that only represent geometric primitives, such as STL or STEP, make subsequent parametric modifications of published models unfeasible.
While tetrode hyperdrives11,12,13 enable recordings from dozens of tetrodes, their assembly and implantation are time-intensive, and their quality is largely dependent on the skill and experience of the individual researcher. In addition, they usually combine the guide tubes that direct the recording electrodes to their target location in one or two larger bundles, therefore limiting the number and spread of areas that can be targeted efficiently.
Other implants14,15 expose the complete skull and allow for the free placement of multiple individual microdrives that carry the recording electrodes. While the placement of independent microdrives16 during surgery time maximizes flexibility, it increases surgery time and can make it difficult to target multiple adjacent areas due to the space requirements of the individual microdrives. In addition, while the implants are open source, they are only published as STL files, making modification difficult.
An example of a drive with a more inherent parametric philosophy is the RatHat17. By providing a surgical stencil that covers the whole dorsal surface of the skull, it allows precise targeting of multiple brain targets without the use of a stereotactic frame during surgery. Multiple implant variations for cannulas, optrodes, or tetrodes are available. However, while the drive is free to use for academic purposes, it is not published open-source, creating a hurdle for researchers to evaluate and use the implant.
Presented in this article is the TD Drive (see Figure 1), a novel 3D-printable implant for extracellular electrode recordings in rats. The TD Drive aims to overcome some of the drawbacks of existing solutions: it allows to target multiple brain areas, mirrored across both hemispheres, with independent wire electrodes simultaneously. Due to its simple design, it can be assembled in a few hours at a relatively low cost by less experienced researchers. The TD Drive is published open-source, in easily modifiable file formats to allow researchers to adjust it to their specific needs. Incorporating a parametric 3D modeling approach from the beginning of the TD Drive&#39;s design process allows the parameters necessary to be changed to be abstracted: to change target locations, researchers can simply edit the parameters representing their dorsoventral and anteroposterior coordinates, without the need for re-designing the drive themselves. The files to modify and manufacture the TD Drive can be found at <a href="https://github.com/3Dneuro/TD_Drive">https://github.com/3Dneuro/TD_Drive</a>.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/66457/66457fig01.jpg" /> 
Figure 1: Overview of the TD Drive. (A) Rendering of a TD Drive with a protective cap. (B) Rendering with inner parts shown. The TD Drive features (a)&#160;multiple, parametrically adjustable recording locations for fixed and moveable electrode wires, an EIB with (b) a high-density Omnetics connector compatible with common tethered and wireless data acquisition systems, and (c) an intuitive channel mapping optimized for recordings with Intan/Open Ephys systems (see Supplementary Figure 1) and (d) a cap to protect the implant during tethered recordings and when no headstage is connected. (C) A guide stencil on the bottom of the TD Drive facilitates the placement of guide cannulas and serves as a redundant verification of implant locations during surgery. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/66457/66457fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
The implant design was piloted in n = 4, validated in n = 8, and confirmed in n= 8 Lister Hooded rats that performed different tasks. The first 4 animals were used to develop the drive and adjust parameters. Then, a full pilot was run with 8 animals (shown in results). A second cohort of 8 animals was run and included in the implant survival analysis. The implant was compatible with tethered sleep recordings and open field recordings (Object Exploration) as well as wireless recording in a large maze (HexMaze 9 m x 5 m) using two different commercial recording systems and headstages. The two cohorts of 8 were recorded with two different acquisition systems - tethered for longer sleep recordings and wireless for large maze exploration recordings. We can conclude that this simple wire drive allows for long-running experiments with larger cohorts by less experienced researchers to enable sleep stage analysis as well as oscillation analysis in multiple brain areas. This is in contrast to most electrophysiology implants to date, which, due to difficulty and time intensity, allow for smaller animal cohorts and usually need very experienced experimenters. However, with this drive, no individual neuron activity can be recorded; thus, the use is limited to investigations of local field potential (LFP) and summation activity.

<table><tbody><tr><td>0.5 mm drill bit&amp;nbsp;</td><td>McMaster</td><td>2951A38</td><td></td></tr><tr><td>1.27 mm pitch interconnected SIP/DIP socket (Mill-Max)</td><td>Mouser Electronic</td><td>575-003101</td><td>For essembling and connection of EEG &amp;amp; GND screws</td></tr><tr><td>5 minute epoxy&amp;nbsp;</td><td>Bison</td><td>Commercially available</td><td>regular off-the-shelf epoxy</td></tr><tr><td>cyanoacrylate glue</td><td>Loctite</td><td></td><td>Super Glue-3&amp;nbsp;</td></tr><tr><td>EEG wire</td><td>Science Products GmbH</td><td>7SS-2T</td><td></td></tr><tr><td>Electrode wire</td><td>Science Products GmbH</td><td>NC7620F</td><td></td></tr><tr><td>Ethanol</td><td>LC</td><td></td><td>For standard pre-operative sterilization procedure of drive</td></tr><tr><td>Fine forceps (5)</td><td>FST</td><td>91150-20</td><td>For wire bundle preperation and handling</td></tr><tr><td>Form 3B</td><td>Formlabs</td><td></td><td>3D printer used to 3D print the self-printed parts of the TD drive</td></tr><tr><td>Gold pins (small)</td><td>Neuralynx, Inc.</td><td>9885</td><td>Attachment of electorde wires to EIB board</td></tr><tr><td>Ground wire</td><td>Science Products GmbH</td><td>SS-3T/A</td><td></td></tr><tr><td>High-density connector&amp;nbsp;</td><td>LabMaker GmbH/Omnetics</td><td>A79026-001</td><td></td></tr><tr><td>Lister Hodded rats</td><td>Charles River Laboratories</td><td>Crl:LIS</td><td>we used male rats, 9-12 weeks of age at arrival</td></tr><tr><td>M1 brass insert</td><td>AliExpress</td><td>Commercially available</td><td>https://aliexpress.com/item/33047616164.html</td></tr><tr><td>M1 tap</td><td>McMaster</td><td>2504A33</td><td></td></tr><tr><td>M1x16 screw</td><td>Bossard</td><td>1096613</td><td></td></tr><tr><td>M1x3 stainless steel screws&amp;nbsp;</td><td>Screws and More</td><td>84213_14985</td><td></td></tr><tr><td>M2.5x5 polyimide screws</td><td>Screws and more</td><td>7985PA25S_50</td><td></td></tr><tr><td>mineral oil</td><td>McMaster</td><td>1244K14</td><td></td></tr><tr><td>Nail polish</td><td>Etos</td><td>Commercially available</td><td>For color coding EEG and GND wires</td></tr><tr><td>painter&#039;s tape</td><td>Gamma</td><td>Commercially available</td><td>For wire bundle preperation</td></tr><tr><td>Pin vise</td><td>McMaster</td><td>8455A16</td><td></td></tr><tr><td>plotting paper</td><td>Canson</td><td>Commercially available</td><td>For wire bundle preperation</td></tr><tr><td>polyimide tubes</td><td>Amazon / Small Parts</td><td>TWPT-0159-30-50</td><td>AWG, 0.0159&quot; ID, 0.0219&quot; OD, 0.0030&quot; Wall, 30&quot; Length</td></tr><tr><td>RHD 32-channel headstage with accelerometer</td><td>Intan Technologies, LLC</td><td>C3324</td><td>For tethered recordings in the sleepbox</td></tr><tr><td>RHD 3-ft (0.9 m) standard SPI cables</td><td>Intan Technologies, LLC</td><td>C3203</td><td>From commutator to headstage</td></tr><tr><td>RHD 6-ft (1.8 m) standard SPI cables</td><td>Intan Technologies, LLC</td><td>C3206</td><td>From OpenEphys box to commutator</td></tr><tr><td>Slip Ring with Flange</td><td>Adafruit</td><td>1196</td><td>Commutator: 22 mm diameter, 12 wires</td></tr><tr><td>Solder flux&amp;nbsp;</td><td>Griffon S-39 50 ml</td><td>Commercially available</td><td>For soldering EEG &amp;amp; GND screws</td></tr><tr><td>soldering paste</td><td>Amazon</td><td>B08CBZ5HC5</td><td></td></tr><tr><td>stainless steel M2 nut&amp;nbsp;</td><td>McMaster</td><td>93935A305</td><td></td></tr><tr><td>Tethered recording setup&amp;nbsp;</td><td>OpenEphys</td><td>Acquasition Board</td><td></td></tr><tr><td>Wireless recording logger</td><td>SpikeGadgets</td><td>miniLogger 32</td><td>For wireless recordings in the task</td></tr><tr><td>Wireless recording setup</td><td>SpikeGadgets</td><td>Main Control Unit (MCU) incl. breakout board and RF transceiver</td><td>For wireless recordings in the task</td></tr></tbody></table>

the td drive: a parametric, open-source implant for multi&#45;area electrophysiological recordings in behaving and sleeping rats

Intricate interactions between multiple brain areas underlie most functions attributed to the brain. The process of learning, as well as the formation and consolidation of memories, are two examples that rely heavily on functional connectivity across the brain. In addition, investigating hemispheric similarities and/or differences goes hand in hand with these multi-area interactions. Electrophysiological studies trying to further elucidate these complex processes thus depend on recording brain activity at multiple locations simultaneously and often in a bilateral fashion. Presented here is a 3D-printable implant for rats, named TD Drive, capable of symmetric, bilateral wire electrode recordings, currently in up to ten distributed brain areas simultaneously. The open-source design was created employing parametric design principles, allowing prospective users to easily adapt the drive design to their needs by simply adjusting high-level parameters, such as anterior-posterior and mediolateral coordinates of the recording electrode locations. The implant design was validated in n = 20 Lister Hooded rats that performed different tasks. The implant was compatible with tethered sleep recordings and open field recordings (Object Exploration) as well as wireless recording in a large maze using two different commercial recording systems and headstages. Thus, presented here is the adaptable design and assembly of a new electrophysiological implant, facilitating fast preparation and implantation.

Using the instructions provided in the protocol, the TD Drive could be built easily by multiple experimenters. After drive development (n = 4), a full pilot was run with eight animals. An additional batch of eight animals was implanted, and experimental data collection was performed. As data analysis has not been completed on these animals, they have been included in the survival analysis, but not in other analyses (e.g., targeting or histology). Implant surgery was performed 2 weeks after arrival (see Figure 3A for the target locations used in the pilot). The implant was performed with usual surgical procedures and lasted ~3 h. An experienced surgeon performed initial implants and could teach both experienced as well as novice experimenters with 2-3 surgeries to independence.
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/66457/66457fig03.jpg" /> 
Figure 3: Implant surgery, sleep data, and broadband activity. (A) Schematic overview showing the target locations for craniotomies (blue circles) and skull screws (green: EEG, blue: GND, gray: anchoring screws, note that two anchoring screws are on the side of the skull). (B) Photograph of implanted animals with a tethered headstage during sleep and wakefulness. (C) Example sleep data from tethered animal PFC (Prelimbic) and HPC (Ca1), divided in REM sleep with theta and NonREM sleep with delta, spindles and ripples. Y axis: microvolt, x axis: seconds. This data can be used for example for sleep scoring or oscillation event detection and analysis (D) Example broadband activity recorded wirelessly in an awake animal (noisy channels on the left were not connected). <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/66457/66457fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/66457/66457fig04.jpg" /> 
Figure 4: Implant durability, delta detections, and histology. (A) Survival plot for the implant for two rounds of longer-running experiments. Of note, on day 85, n = 8 finished the experiment and were planned to be perfused. (B) Data example for stability. Shown is the count of delta detections in the hippocampal channel over recording days (~3 days per week). Each animal showed a normal variation depending on the amount of sleep, but there was no general drift over time in the signal and thus detections. (C) Representative histology showing bilateral targeting for one rat. Left column: left hemisphere, right column: right hemisphere. AP coordinates indicate anteroposterior coordinates of the depicted slice, and arrows point to lesions in targeted areas. Magnification: 1.6x. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/66457/66457fig04large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
All animals recovered well and tolerated the implant (Figure 3B). Frontal and retrosplenial electrodes were fixed, but the hippocampal bundles were movable. Hippocampal bundles were implanted at a dorsoventral depth of 2 mm and adjusted to maximize HPC coverage during 2 weeks of surgery recovery, where the signal was checked live during sleep habituation periods. In 7 out of 8 animals, all target sites were reached on at least one hemisphere (Table 2 for hit rates, see Figure 4C for representative histology). Wake and sleep recordings were performed successfully tethered in a recording box, as well as wireless recordings in a larger maze (example data Figure 3C,D). Animals kept the implants for 2 months, when individual animals would start losing them; however, the majority of animals kept the implants until the experimental end day 85-100 after implant (Figure 4A). During this time, the LFP remained stable, as can be seen in an example analysis where delta oscillations were detected (Figure 4B). There was normal variability across time but no systematic drift of the signal in any of the recorded brain areas (including the pyramidal layer of CA1). It is recommended that experiments be ended within 10-15 weeks after surgery. All EIBs could be recovered.
We have applied this implant mainly to measure sleep stages and sleep oscillations in response to learning and other interventions. For example, how oral CBD intake influences oscillation occurrence and coherence across brain areas (see Samanta et al.20).
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Parameter</td>
			<td>Minimum value (mm)</td>
			<td>Maximum value (mm)</td>
		</tr>
		<tr>
			<td>medioLateralSite1</td>
			<td>0.75</td>
			<td>2</td>
		</tr>
		<tr>
			<td>medioLateralSite2</td>
			<td>1.5</td>
			<td>5</td>
		</tr>
		<tr>
			<td>medioLateralSite3</td>
			<td>0.75</td>
			<td>2</td>
		</tr>
	</tbody>
</table>
Table 1: Overview of the manually imposed limits on the parameters controlling the mediolateral coordinates of the recording sites.
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Hemisphere</td>
			<td>PFC</td>
			<td>RSC</td>
			<td>CA1 pyr.</td>
		</tr>
		<tr>
			<td>Right</td>
			<td>8 of 8</td>
			<td>5 of 8</td>
			<td>6 of 8</td>
		</tr>
		<tr>
			<td>Left</td>
			<td>8 of 8</td>
			<td>7 of 8</td>
			<td>7 of 8</td>
		</tr>
	</tbody>
</table>
Table 2: Hit rate for pilot of 8 animals. In 4 out of 8 animals, all electrodes were placed correctly. However, in 7 out of 8 animals, all brain areas were correctly targeted in at least one hemisphere (with the exception of 1 rat missing the CA1 pyramidal layer).
Supplementary Figure 1: TD Drive architecture. (Top)&#160;Overview of the channel mapping for the TD Drive when used with an Intan RHD32 headstage. (Bottom) An additional illustration of the wire bundle configurations.<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/66457/Supplementary Figure S1.zip" target="_blank">Please click here to download this File.</a>
Supplementary Figure 2: Additional pictures of the TD Drive at several stages of the building process. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/66457/Supplementary Figure S2.zip" target="_blank">Please click here to download this File.</a>
Supplementary File 1: An example protocol for implantation of the TD Drive. The procedures and target locations are adjusted to the authors&#39; research questions and institutional policies.<a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/66457/Supplementary - TD drive implantation.zip" target="_blank">Please click here to download this File.</a>

Read this Scientific Article Protocol about The TD Drive: A Parametric, Open-Source Implant for Multi-Area Electrophysiological Recordings in Behaving and Sleeping Rats at JoVE.com

Author Spotlight: Deciphering Memory and Learning Through Neural Implants for Multi&#45;Region Brain Studies

Here, we present a unique, 3D-printable implant for rats, named TD Drive, capable of symmetric, bilateral wire electrode recordings, currently in up to ten distributed brain areas simultaneously.

The TD Drive: A Parametric, Open-Source Implant for Multi&#45;Area Electrophysiological Recordings in Behaving and Sleeping Rats

Intricate interactions between multiple brain areas underlie most functions attributed to the brain. The process of learning, as well as the formation and ...

the-td-drive-parametric-open-source-implant-for-multi-area

Nanyang Technological University

Research

JoVE Journal

Neuroscience

1.1K Views.  Radboud University. Ons onderzoeksdoel is om de neurale mechanismen die ten grondslag liggen aan geheugenverwerking beter te begrijpen, met name om de interacties tussen specifieke hersengebieden in realtime te onderzoeken tijdens verschillende leertijdstippen en ook tijdens de slaap. In dit opzicht hebben we hier een nieuw drive-implantaat ontwikkeld dat ons in staat stelt om neurale activiteit tegelijkertijd te bekijken in meerdere hersengebieden bij vrij bewegende ratten tijd...

Video: Auteur in de schijnwerpers: geheugen ontcijferen en leren door middel van neurale implantaten voor hersenstudies in meerdere regio's

Surgical Implantation of Chronic Neural Electrodes for Recording Single Unit Activity and Electrocorticographic Signals

The success of long-term electrophysiological recordings often depends on the quality of the implantation surgery. Here we provide useful information for surgeons who are learning the process of implanting electrode systems. We demonstrate the implantation procedure of both a penetrating and a surface electrode. The surgical process is described from start to finish, including detailed descriptions of each step throughout the procedure. It should also be noted that this video guide is focused towards procedures conducted in rodent models and other small animal models. Modifications of the described procedures are feasible for other animal models.

We provide useful information for surgeons who are learning the process of implanting chronic neural recording electrodes. Techniques for both penetrating and surface electrode systems are described in a rodent animal model.

The success of long-term electrophysiological recordings often depends on the quality of the implantation surgery.  Here we provide useful information for ...

A Wireless, Bidirectional Interface for In Vivo Recording and Stimulation of Neural Activity in Freely Behaving Rats

In vivo electrophysiology is a powerful technique to investigate the relationship between brain activity and behavior at a millisecond and micrometer scale. However, current methods mostly rely on tethered cable recordings or only use unidirectional systems, allowing either recording or stimulation of neural activity, but not at the same time or same target. Here, a new wireless, bidirectional device for simultaneous multichannel recording and stimulation of neural activity in freely behaving rats is described. The system operates through a single portable head stage that both transmits recorded activity and can be targeted in real-time for brain stimulation using a telemetry-based multichannel software. The head stage is equipped with a preamplifier and a rechargeable battery, allowing stable long-term recordings or stimulation for up to 1 h. Importantly, the head stage is compact, weighs 12 g (including battery) and thus has minimal impact on the animal&#180;s behavioral repertoire, making the method applicable to a broad set of behavioral tasks. Moreover, the method has the major advantage that the effect of brain stimulation on neural activity and behavior can be measured simultaneously, providing a tool to assess the causal relationships between specific brain activation patterns and behavior. This feature makes the method particularly valuable for the field of deep brain stimulation, allowing precise assessment, monitoring, and adjustment of stimulation parameters during long-term behavioral experiments. The applicability of the system has been validated using the inferior colliculus as a model structure.

A Wireless, Bidirectional Interface for In Vivo Recording and Stimulation of Neural Activity in Freely Behaving Rats

A wireless, bidirectional system for multi-channel neural recordings and stimulation in freely behaving rats is introduced. The system is light and compact, thus having minimal impact on the animal&#180;s behavioral repertoire. Moreover, this bidirectional system provides a sophisticated tool to assess causal relationships between brain activation patterns and behavior.

In vivo electrophysiology is a powerful technique to investigate the relationship between brain activity and behavior at a millisecond and micrometer ...

Behavior

High-density Electroencephalographic Acquisition in a Rodent Model Using Low-cost and Open-source Resources

Advanced electroencephalographic analysis techniques requiring high spatial resolution, including electrical source imaging and measures of network connectivity, are applicable to an expanding variety of questions in neuroscience. Performing these kinds of analyses in a rodent model requires higher electrode density than traditional screw electrodes can accomplish. While higher-density electroencephalographic montages for rodents exist, they are of limited availability to most researchers, are not robust enough for repeated experiments over an extended period of time, or are limited to use in anesthetized rodents.1-3 A proposed low-cost method for constructing a durable, high-count, transcranial electrode array, consisting of bilaterally implantable headpieces is investigated as a means to perform advanced electroencephalogram analyses in mice or rats.

Procedures for headpiece fabrication and surgical implantation necessary to produce high signal to noise, low-impedance electroencephalographic and electromyographic signals are presented. While the methodology is useful in both rats and mice, this manuscript focuses on the more challenging implementation for the smaller mouse skull. Freely moving mice are only tethered to cables via a common adapter during recording. One version of this electrode system that includes 26 electroencephalographic channels and 4 electromyographic channels is described below.

Instructions for the low-cost construction and surgical implantation of a chronic transcranial high-density electroencephalographic montage into mice are provided. Signal recording, extraction, and processing techniques are also described.

Advanced electroencephalographic analysis techniques requiring high spatial resolution, including electrical source imaging and measures of network ...

Simultaneous Recordings of Cortical Local Field Potentials, Electrocardiogram, Electromyogram, and Breathing Rhythm from a Freely Moving Rat

Monitoring the physiological dynamics of the brain and peripheral tissues is necessary for addressing a number of questions about how the brain controls body functions and internal organ rhythms when animals are exposed to emotional challenges and changes in their living environments. In general experiments, signals from different organs, such as the brain and the heart, are recorded by independent recording systems that require multiple recording devices and different procedures for processing the data files. This study describes a new method that can simultaneously monitor electrical biosignals, including tens of local field potentials in multiple brain regions, electrocardiograms that represent the cardiac rhythm, electromyograms that represent awake/sleep-related muscle contraction, and breathing signals, in a freely moving rat. The recording configuration of this method is based on a conventional micro-drive array for cortical local field potential recordings in which tens of electrodes are accommodated, and the signals obtained from these electrodes are integrated into a single electrical board mounted on the animal's head. Here, this recording system was improved so that signals from the peripheral organs are also transferred to an electrical interface board. In a single surgery, electrodes are first separately implanted into the appropriate body parts and the target brain areas. The open ends of all of these electrodes are then soldered to individual channels of the electrical board above the animal's head so that all of the signals can be integrated into the single electrical board. Connecting this board to a recording device allows for the collection of all of the signals into a single device, which reduces experimental costs and simplifies data processing, because all data can be handled in the same data file. This technique will aid the understanding of the neurophysiological correlates of the associations between central and peripheral organs.

This study introduces a method for the simultaneous recording of local field potentials in the brain, electrocardiograms, electromyograms, and breathing signals of a freely moving rat. This technique, which reduces experimental costs and simplifies data analysis, will contribute to the understanding of the interactions between the brain and peripheral organs.

Monitoring the physiological dynamics of the brain and peripheral tissues is necessary for addressing a number of questions about how the brain controls ...

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 ...

Flexible Multi-Region Neural Recording Device for Epilepsy Research

An Integrated Method for Crafting Flexible and Convenient Electrophysiological Optrodes for Multi-Region In Vivo Recording

Epilepsy is a neurological disorder characterized by synchronized abnormal discharges involving multiple brain regions. Focal lesions facilitate the propagation of epileptic signals through associated neural circuits. Therefore, in vivo recording of local field potential (LFP) from the critical brain regions is&#160;essential for deciphering the circuits involved in seizure propagation. However, current methods for electrode fabrication and implantation lack flexibility. Here, we present a handy device designed for electrophysiological recordings (LFPs and electroencephalography [EEG]) across multiple regions. Additionally, we seamlessly integrated optogenetic manipulation and calcium signaling recording with LFP recording. Robust after-discharges were observed in several separate regions during epileptic seizures, accompanied by increasing&#160;calcium signaling. The approach used in this study offers a convenient and flexible strategy for synchronous neural recordings across diverse regions of the brain. It holds the potential for advancing research on neurological disorders by providing insights into the neural profiles of multiple regions involved in these disorders.

Author Spotlight: Unraveling Neural Communication and Circuit Interactions in Health and Disease

We have developed a simplified and cost-effective approach for electrode fabrication and conducted recordings of signals across multiple regions in freely moving mice. Utilizing optogenetics, alongside multi-region electrophysiology and calcium signal recording, enabled the revelation of neuronal activities across regions in the seizure kindling model.

Epilepsy is a neurological disorder characterized by synchronized abnormal discharges involving multiple brain regions. Focal lesions facilitate the ...

In Vivo Electrophysiological Recordings of Brain Activities from Multiple Sites in Rats

Source: Haumesser, J. K., et al. <a href="https://app-jove-com.remotexs.ntu.edu.sg/v/55940">Acute In Vivo Electrophysiological Recordings of Local Field Potentials and Multi-unit Activity from the Hyperdirect Pathway in Anesthetized Rats.</a> J. Vis. Exp.(2017).
This video demonstrates the detailed procedure for preparing an anesthetized rat for electrophysiological recordings of brain activity from multiple sites. The scalp is dissected to access the skull, and holes are drilled at precise locations to install and secure electrodes. Tungsten microwire electrodes are then inserted into the targeted location to record the data.

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

JoVE Encyclopedia of Experiments

Neurophysiology

Electrophysiology Techniques

Implanting a Wireless Bidirectional Microelectrode System in a Rat Brain

Source: Melo-Thomas, L., et al., <a href="https://app-jove-com.remotexs.ntu.edu.sg/v/56299">A Wireless, Bidirectional Interface for In Vivo Recording and Stimulation of Neural Activity in Freely Behaving Rats.</a> J. Vis. Exp. (2017)
The video demonstrates a procedure for implanting a wireless bidirectional multichannel electrode unit into a rat brain to record and stimulate multichannel neural networks.

Subdural Implantation of a Soft Electrocorticography Array for Cortical Electrophysiology Recording in Minipigs

Source: Fallegger, F. et al., <a href="https://app-jove-com.remotexs.ntu.edu.sg/v/64997">Subdural Soft Electrocorticography (ECoG) Array Implantation and Long-Term Cortical Recording in Minipigs.</a>&#160;J. Vis. Exp. (2023).
This video demonstrates the implantation of a soft electrocorticography array and the long-term cortical recordings in a minipig. It outlines the steps involved in surgically implanting the array over the minipig&#39;s auditory cortex and recording both baseline and sound stimulus-evoked neuronal action potentials.

Implanting an On-Head Electrode System in a Rat Model for Real-Time Seizure Detection

Source: Koz&#225;k, G., et al. <a href="https://app-jove-com.remotexs.ntu.edu.sg/v/56669">Chronic Transcranial Electrical Stimulation and Intracortical Recording in Rats.</a> J. Vis. Exp. (2018).
This video demonstrates the method of implanting an on-head electrode system in an anesthetized rat for real-time seizure detection. The procedure includes placing stimulation and recording electrodes, securing them with dental cement, and connecting them to a head-mounted amplifier.

The TD Drive: A Parametric, Open-Source Implant for Multi-Area Electrophysiological Recordings in Behaving and Sleeping Rats

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