We would like to acknowledge Justin Riceberg for technical assistance in the testing of the headstage. This work was supported in part by National Institutes of Health Grants MH65658, MH073689, and F30 AG034003-01A1, and the Mount Sinai School of Medicine.

1. Headstage Design and Fabrication Overview
A completed headstage pre-amplifier system consists of the following components:
<ol>
	<li>A computer designed integrated circuit board with four channels of recording and two channels of stimulation.</li>
	<li>Electrodes that relay the recordings and stimulation channels to the appropriate connectors on the animals head stage.</li>
	<li>A tether cable and interface that relays the recording and stimulation channels to a slip-ring commutator.</li>
	<li>Two forms of waterproofing on the head stage and on the integrated circuit.</li>
</ol>
2. Design and Layout of the Headstage
We designed a printed integrated circuit board with 4 source followers and 2 pass through stimulation channels using a commercially available software CAD package (www.expresspcb.com). One headstage is designed, and the design pattern is tiled across a larger sheet of circuit board to provide many headstages at a lower cost. The CAD file is transmitted to the printed circuit board (PCB) manufacturing service where double sided, two layer boards are printed using top and bottom copper layers with all holes plated through. The boards use tin/lead solder plated traces and pads that correspond to industry standard FR-4 laminate. The PCB can be ordered and shipped the next business day. Individual headstages are cut from the large tiled PCB sheet and electronic components are connected with solder. An example layout of the headstage used in this protocol is shown (Figure 1). Please see the manufacturer website for detailed instructions and tips on designing a PCB.
3. Preparation and Soldering of Electronic Components
All electronic components used in this protocol are of the Surface Mount Device (SMD) type. The footprint of each device type (resistor, capacitor, etc.) was chosen to minimize wasted space on the headstage, but larger SMD components may be used if necessary.
<ol>
	<li>Organize your components on the circuit board and prepare them for soldering.</li>
	<li>Place a small amount of solder on the tin/lead pad to be soldered and bring the tip of the soldering iron close to melt and adhere the solder to the pad.</li>
	<li>Solder the capacitors first, resistors next, and then the operational amplifiers.</li>
	<li>The op-amps can be destroyed by over heating. We used a variable heat soldering gun and the lowest heat necessary to melt the solder. Minimize the heating time used to make a good solder joint. We found it convenient to create a small reservoir of solder that flows into the footprint pad by applying solder along the communication or power traces.</li>
	<li>Test that the resistance across your resistors meets the expected value using an ohmmeter.</li>
	<li>Inspect each pad closely to ensure that no solder is connecting or bridging adjacent pads. If there is a solder bridge, heat and melt the solder and use a tweezer to break the bridge.</li>
</ol>
4. Assembly and Fabrication of Implant and Tether Interfaces
<ol>
	<li>Insert a 23 Ga hypodermic tubing into one of the unused ports of the 9pin ABS socket for mechanical support.</li>
	<li>Cut six 1 cm length pieces of insulated magnetic wire for connecting the female amphenol pins to the ABS socket.</li>
	<li>Solder the female pins to the magnetic wire using a small amount of solder in each pin, and by heating the pin from the tip.</li>
	<li>Solder the other end of each magnetic wire into the ABS sockets.</li>
	<li>Position the male - female MillMax pins over the pads on the tether side of the headstage, and squeeze the pins over the PCB to ensure a pressure fit. Then, solder each pin to each pad in order.</li>
	<li>Position the ring nut over the neural implant connector and push all the female pins into the desired slots on the plastic base.</li>
	<li>Apply acrylic glue (krazy glue) to the top of the ABS socket connector and secure it to the base of the headstage. Glue the 23Ga tube to the tether side of the headstage for support.</li>
</ol>
5. Waterproofing the Headstage
<ol>
	<li>To waterproof the headstage, encase the entire integrated circuit and any exposed metal surfaces with 5 minute epoxy. Allow 5-10 minutes for initial drying, and 60 minutes for permanent drying.</li>
	<li>Poster Tack putty should be applied to the surface the 9 pin ABS socket around the female pins protruding from the animal end.</li>
	<li>For maximal waterproofing, the ABS socket and ABS plug should be mated and the ring nut should be tightened. A small strip of parafilm should be wrapped around the interface to prevent water from contacting the pin connectors.</li>
</ol>
Secrets to Success
<ol>
	<li>When soldering the operational amplifier, do not overheat the plastic package. If there is visible burning or melting, remove the op-amp and replace it. Applying too much heat may damage the op amp without visible melting. Test each channel with a function generator after soldering.</li>
	<li>Make sure there are no stray connections or solder bridges on the headstage. Solder wick can be used to remove components or stray solder.</li></ol>
6. Representative Results
A good recording will follow an input source signal without cutting in and out during movement. To test the headstage, the user should use a function generator as an input to each recording pin and evaluate the waveforms at the Mill Max header output end. Physically moving the headstage should not influence the shape of recorded waveforms.
<img src="/files/ftp_upload/2155/2155fig1.jpg" alt="Figure 1" /> Figure 1. (A) Schematic view of top layer of printed circuit board (PCB). Red lines indicate copper traces. Yellow lines indicate optional silkscreen layer for positioning of electronic parts. Shown are the operational amplifier placement (central yellow square), resistors (smaller yellow squares) and capacitors (smallest yellow squares). (B) Schematic view of bottom layer of PCB. Green lines indicate copper traces. Large green filled area represents ground plate. A model file of this schematic is provided for download.

<ol>
	<li>Morris, R. G., Garrud, P., Rawlins, J. N., O'Keefe, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Place+navigation+impaired+in+rats+with+hippocampal+lesions.">Place navigation impaired in rats with hippocampal lesions.</a> Nature. 297, 681-683 (1982).</li><li>Rolston, J. D., Gross, R. E., Potter, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+low-cost+multielectrode+system+for+data+acquisition+enabling+real-time+closed-loop+processing+with+rapid+recovery+from+stimulation+artifacts.+Front.">A low-cost multielectrode system for data acquisition enabling real-time closed-loop processing with rapid recovery from stimulation artifacts. Front.</a> Neuroengineering. 2, 12-12 (2009).</li><li>Fee, M. S., Leonardo, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Miniature+motorized+microdrive+and+commutator+system+for+chronic+neural+recording+in+small+animals.">Miniature motorized microdrive and commutator system for chronic neural recording in small animals.</a> J. Neurosci. Methods. 112, 83-94 (2001).</li><li>Shirvalkar, P. R., Rapp, P. R., Shapiro, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bidirectional+changes+to+hippocampal+theta+gamma+oscillations+predict+memory+for+recent+spatial+episodes.">Bidirectional changes to hippocampal theta gamma oscillations predict memory for recent spatial episodes.</a> Proc Natl Acad Sci U S A. 107 (15), 7054-709 (2010).</li></ol>

No conflicts of interest declared.

Water maze based behavioral tasks provide effective tools to probe animals' cognitive abilities and representations in real time 1. The use of lightweight and cost effective headstage preamplifiers is especially critical in behavioral neurophysiology applications involving the water maze. Because escaping the cold water provides intrinsic motivation for animals in these tasks, their behavior can be tested in repeated trials without the difficulties of motivating animals on dry mazes. The low cost headstage pre...

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		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>Custom designed Integrated Circuit Board</td>
<td>&nbsp;</td>
<td>ExpressPCB.com</td>
<td>Custom</td>
<td>2 layer double sided PCB</td>
</tr>
<tr>
<td>Surface mount Resistors</td>
<td>&nbsp;</td>
<td>Mouser Electronics</td>
<td>RK73B1JTTDD156J</td>
<td>1/10 W, 15 M Ohm 0603, Thick film</td>
</tr>
<tr>
<td>SMD Capacitors </td>
<td>&nbsp;</td>
<td>Newark Electronics</td>
<td>0402YD104KAT2A</td>
<td>0.1 uF (0402)</td>
</tr>
<tr>
<td>SMD Operational Amplifier (quad FET)</td>
<td>&nbsp;</td>
<td>Mouser Electronics</td>
<td>595-TLC2274AIPW</td>
<td>Quad FET - low noise</td>
</tr>
<tr>
<td>9 pin ABS socket</td>
<td>&nbsp;</td>
<td>Ginder Scientific</td>
<td>GS09SKT-220</td>
<td>For animal connection</td>
</tr>
<tr>
<td>9-pin ABS Plug</td>
<td>&nbsp;</td>
<td>Ginder Scientific</td>
<td>GS09PLG-220</td>
<td>To be implanted in animal</td>
</tr>
<tr>
<td>Black Delrin Ring Nut</td>
<td>&nbsp;</td>
<td>Ginder Scientific</td>
<td>GS09BDN-220</td>
<td>&nbsp;</td>
<tr>
<td>Black Delrin Cap Nut</td>
<td>&nbsp;</td>
<td>Ginder Scientific</td>
<td>GS09BDC-220</td>
<td>For protecting animal's implant</td>
</tr>
<tr>
<td>Amphenol pins (male)</td>
<td>&nbsp;</td>
<td>Ginder Scientific</td>
<td>220-P02</td>
<td>&nbsp;</td>
<tr>
<td>Amphenol pins (female)</td>
<td>&nbsp;</td>
<td>Ginder Scientific</td>
<td>220-S02</td>
<td>&nbsp;</td>
<tr>
<td>5-minute epoxy</td>
<td>&nbsp;</td>
<td>Devcon Inc.</td>
<td>S-208 / 20845</td>
<td>&nbsp;</td>
<tr>
<td>Poster Tack Putty</td>
<td>&nbsp;</td>
<td>Elmer's</td>
<td>026000015318</td>
<td>&nbsp;</td>
<tr>
<td>Rosin Core Solder</td>
<td>&nbsp;</td>
<td>Radio Shack</td>
<td>64-009</td>
<td>&nbsp;</td>
<tr>
<td>Soldering Iron </td>
<td>&nbsp;</td>
<td>Weller</td>
<td>Pyropen WSTA6</td>
<td>(adjustable heat)</td>
</tr>
<tr>
<td>Metal tweezers</td>
<td>&nbsp;</td>
<td>Fine Science Tools</td>
<td>Size 5</td>
<td>&nbsp;</td>
<tr>
<td>Parafilm sheets</td>
<td>&nbsp;</td>
<td>American National Can</td>
<td>Parafilm 4" x 250'</td>
<td>&nbsp;</td>
<tr>
<td>Magnet wire</td>
<td>&nbsp;</td>
<td>Belden</td>
<td>8052</td>
<td>Enamel Coated</td>
</tr>
<tr>
<td>Ammeter/ Multimeter</td>
<td>&nbsp;</td>
<td>Fluke Mfg Co.</td>
<td>77 Multimeter</td>
<td>&nbsp;</td>
<tr>
<td>Millmax Double Row Headers</td>
<td>&nbsp;</td>
<td>Millmax / Mouser</td>
<td>575 - 002101</td>
<td>0.05"</td>
</tr>
<tr>
<td>Solder Wick</td>
<td>&nbsp;</td>
<td>Chemtronics</td>
<td>7-10L</td>
<td>0.75 in.</td>
</tr>		</tbody>
		</table>
		</div>

design and construction of a cost effective headstage for simultaneous neural stimulation and recording in the water maze

Headstage preamplifiers and source followers are commonly used to study neural activity in behavioral neurophysiology experiments. Available commercial products are often expensive, not easily customized, and not submersible. Here we describe a method to design and build a customized, integrated circuit headstage for simultaneous 4-channel neural recording and 2-channel simulation in awake, behaving animals. The headstage is designed using a free, commercially available CAD-type design package, and can be modified easily to accommodate different scales (e.g. to add channels). A customized printed circuit board is built using surface mount resistors, capacitors and operational amplifiers to construct the unity gain source follower circuit. The headstage is made water-proof with a combination of epoxy, parafilm and a synthetic rubber putty. We have successfully used this device to record local field potentials and stimulate different brain regions simultaneously via independent channels in rats swimming in a water maze. The total cost is &lt; $30/unit and can be manufactured readily.

Watch this Scientific Journal Video about Design and Construction of a Cost Effective Headstage for Simultaneous Neural Stimulation and Recording in the Water Maze at JoVE.com

Design and Construction of a Cost Effective Headstage for Simultaneous Neural Stimulation and Recording in the Water Maze

We present a low-cost method to design and construct a light headstage pre-amplifier system with simultaneous neural recording and stimulation capability. This device can be waterproofed for use in swimming animals.

Headstage preamplifiers and source followers are commonly used to study neural activity in behavioral neurophysiology experiments. Available commercial ...

design-construction-cost-effective-headstage-for-simultaneous-neural

Research

JoVE Journal

Neuroscience

10.6K Views.  Mount Sinai School of Medicine. We present a low-cost method to design and construct a light headstage pre-amplifier system with simultaneous neural recording and stimulation capability. This device can be waterproofed for use in swimming animals.

Video: Design and Construction of a Cost Effective Headstage for Simultaneous Neural Stimulation and Recording in the Water Maze

Morris Water Maze Test for Learning and Memory Deficits in Alzheimer&#39;s Disease Model Mice

The Morris Water Maze (MWM) was first established by neuroscientist Richard G. Morris in 1981 in order to test hippocampal-dependent learning, including acquisition of spatial memoryand long-term spatial memory 1. The MWM is a relatively simple procedure typically consisting of six day trials, the main advantage being the differentiation between the spatial (hidden-platform) and non-spatial (visible platform) conditions 2-4. In addition, the MWM testing environment reduces odor trail interference 5. This has led the task to be used extensively in the study of the neurobiology and neuropharmacology of spatial learning and memory. The MWM plays an important role in the validation of rodent models for neurocognitive disorders such as Alzheimer&#x2019;s Disease 6, 7. In this protocol we discussed the typical procedure of MWM for testing learning and memory and data analysis commonly used in Alzheimer&#x2019;s disease transgenic model mice.

Morris Water Maze Test for Learning and Memory Deficits in Alzheimer&#039;s Disease Model Mice

The Morris Water Maze is a behavioral task to test hippocampal-dependent learning and memory. It has been widely used in the study of neurobiology, neuropharmacology and neurocognitive disorders in rodent models.

The Morris Water Maze (MWM) was first established by neuroscientist Richard G. Morris in 1981 in order to test hippocampal-dependent learning, including ...

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

The ability to chronically record from populations of neurons in freely behaving animals has proven an invaluable tool for dissecting the function of neural circuits underlying a variety of natural behaviors, including navigation1 , decision making 2,3, and the generation of complex motor sequences4,5,6. Advances in precision machining has allowed for the fabrication of light-weight devices suitable for chronic recordings in small animals, such as mice and songbirds. The ability to adjust the electrode position with small remotely controlled motors has further increased the recording yield in various behavioral contexts by reducing animal handling.6,7
 Here we describe a protocol to build an ultra-light motorized microdrive for long-term chronic recordings in small animals. Our design evolved from an earlier published version7, and has been adapted for ease-of use and cost-effectiveness to be more practical and accessible to a wide array of researchers. This proven design 8,9,10,11 allows for fine, remote positioning of electrodes over a range of ~ 5 mm and weighs less than 750 mg when fully assembled. We present the complete protocol for how to build and assemble these drives, including 3D CAD drawings for all custom microdrive components.

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.

The ability to chronically record from populations of neurons in freely behaving animals has proven an invaluable tool for dissecting the function of ...

Whole Cell Patch Clamp for Investigating the Mechanisms of Infrared Neural Stimulation

It has been demonstrated in recent years that pulsed, infrared laser light can be used to elicit electrical responses in neural tissue, independent of any further modification of the target tissue. Infrared neural stimulation has been reported in a variety of peripheral and sensory neural tissue in vivo, with particular interest shown in stimulation of neurons in the auditory nerve. However, while INS has been shown to work in these settings, the mechanism (or mechanisms) by which infrared light causes neural excitation is currently not well understood. The protocol presented here describes a whole cell patch clamp method designed to facilitate the investigation of infrared neural stimulation in cultured primary auditory neurons. By thoroughly characterizing the response of these cells to infrared laser illumination in vitro under controlled conditions, it may be possible to gain an improved understanding of the fundamental physical and biochemical processes underlying infrared neural stimulation.

Infrared nerve stimulation has been proposed as an alternative to electrical stimulation in a range of nerve types, including those associated with the auditory system. This protocol describes a patch clamp method for studying the mechanism of infrared nerve stimulation in a culture of primary auditory neurons.

It has been  demonstrated in recent years that pulsed, infrared laser light can be used to  elicit electrical responses in neural tissue, independent of ...

Fabrication of High Contact-Density, Flat-Interface Nerve Electrodes for Recording and Stimulation Applications

Many attempts have been made to manufacture multi-contact nerve cuff electrodes that are safe, robust and reliable for long term neuroprosthetic applications. This protocol describes a fabrication technique of a modified cylindrical nerve cuff electrode to meet these criteria. Minimum computer-aided design and manufacturing (CAD and CAM) skills are necessary to consistently produce cuffs with high precision (contact placement 0.51 &#177; 0.04 mm) and various cuff sizes. The precision in spatially distributing the contacts and the ability to retain a predefined geometry accomplished with this design are two criteria essential to optimize the cuff&#39;s interface for selective recording and stimulation. The presented design also maximizes the flexibility in the longitudinal direction while maintaining sufficient rigidity in the transverse direction to reshape the nerve by using materials with different elasticities. The expansion of the cuff&#39;s cross sectional area as a result of increasing the pressure inside the cuff was observed to be 25% at 67 mm Hg. This test demonstrates the flexibility of the cuff and its response to nerve swelling post-implant. The stability of the contacts&#39; interface and recording quality were also examined with contacts&#39; impedance and signal-to-noise ratio metrics from a chronically implanted cuff (7.5 months), and observed to be 2.55 &#177; 0.25 k&#8486; and 5.10 &#177; 0.81 dB respectively.

This article provides a detailed description on the fabrication process of a high contact-density flat interface nerve electrode (FINE). This electrode is optimized for recording and stimulating neural activity selectively within peripheral nerves.

Many attempts have been made to manufacture multi-contact nerve cuff electrodes that are safe, robust and reliable for long term neuroprosthetic ...

Time-dependent Increase in the Network Response to the Stimulation of Neuronal Cell Cultures on Micro-electrode Arrays

Micro-electrode arrays (MEAs) can be used to investigate drug toxicity, design paradigms for next-generation personalized medicine, and study network dynamics in neuronal cultures. In contrast with more traditional methods, such as patch-clamping, which can only record activity from a single cell, MEAs can record simultaneously from multiple sites in a network, without requiring the arduous task of placing each electrode individually. Moreover, numerous control and stimulation configurations can be easily applied within the same experimental setup, allowing for a broad range of dynamics to be explored. One of the key dynamics of interest in these in vitro studies has been the extent to which cultured networks display properties indicative of learning. Mouse neuronal cells cultured on MEAs display an increase in response following training induced by electrical stimulation. This protocol demonstrates how to culture neuronal cells on MEAs; successfully record from over 95% of the plated dishes; establish a protocol to train the networks to respond to patterns of stimulation; and sort, plot, and interpret the results from such experiments. The use of a proprietary system for stimulating and recording neuronal cultures is demonstrated. Software packages are also used to sort neuronal units. A custom-designed graphical user interface is used to visualize post-stimulus time histograms, inter-burst intervals, and burst duration, as well as to compare the cellular response to stimulation before and after a training protocol. Finally, representative results and future directions of this research effort are discussed.

Mouse neuronal cells cultured on multi-electrode arrays display an increase in response following electrical stimulation. This protocol demonstrates how to culture neurons, how to record activity, and how to establish a protocol to train the networks to respond to patterns of stimulation.

Micro-electrode arrays (MEAs) can be used to investigate drug toxicity, design paradigms for next-generation personalized medicine, and study 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 ...

Construction of an Improved Multi-Tetrode Hyperdrive for Large-Scale Neural Recording in Behaving Rats

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.

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.

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 ...

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

Multichannel electrode arrays offer insight into the working brain and serve to elucidate neural processes at the single-cell and circuit levels. Development of these tools is crucial for understanding complex behaviors and cognition and for advancing clinical applications. However, it remains a challenge to densely record from cell populations stably and continuously over long time periods. Many popular electrodes, such as tetrodes and silicon arrays, feature large cross-diameters that produce damage upon insertion and elicit chronic reactive tissue responses associated with neuronal death, hindering the recording of stable, continuous neural activity. In addition, most wire bundles exhibit broad spacing between channels, precluding simultaneous recording from a large number of cells clustered in a small area. The carbon fiber microelectrode arrays described in this protocol offer an accessible solution to these concerns. The study provides a detailed method for fabricating carbon fiber microelectrode arrays that can be used for both acute and chronic recordings in vivo. The physical properties of these electrodes make them ideal for stable and continuous long-term recordings at high cell densities, enabling the researcher to make robust, unambiguous recordings from single units across months.

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

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.

Multichannel electrode arrays offer insight into the working brain and serve to elucidate neural processes at the single-cell and circuit levels. ...

Optrode Array for Simultaneous Optogenetic Modulation and Electrical Neural Recording

During the last decade, optogenetics has become an essential tool for the investigation of neural signaling due to its unique capability of selective neural modulation or monitoring. As specific types of neuronal cells can be genetically modified to express opsin proteins, optogenetics enables optical stimulation or inhibition of the selected neurons. There have been several technological advances in the optical system for optogenetics. Recently, it was proposed to combine the optical waveguide for light delivery with electrophysiological recording to simultaneously monitor the neural responses to optogenetic stimulation or inhibition. In this study, an implantable optrode array (2x2 optical fibers) was developed with embedded multichannel electrodes. 
A light-emitting diode (LED) was employed as a light source, and a microfabricated microlens array was integrated to provide sufficient light power at the tip of the optical fibers. The optrode array system comprises the disposable part and the reusable part. The disposable part has optical fibers and electrodes, while the reusable part has the LED and electronic circuitry for light control and neural signal processing. The novel design of the implantable optrode array system is introduced in the accompanying video in addition to the procedure of the optrode implantation surgery, optogenetic light stimulation, and the electrophysiological neural recording. The results of in vivo experiments successfully showed time-locked neural spikes evoked by the light stimuli from hippocampal excitatory neurons of mice.

Here, we present the fabrication method of an optrode system with optical fibers for light delivery and an electrode array for neural recording. In vivo experiments with transgenic mice expressing channelrhodopsin-2 show the feasibility of the system for simultaneous optogenetic stimulation and electrophysiological recording.

During the last decade, optogenetics has become an essential tool for the investigation of neural signaling due to its unique capability of selective ...

Automated Multimodal Stimulation and Simultaneous Neuronal Recording from Multiple Small Organisms

Fluorescent genetically encoded calcium indicators have contributed greatly to our understanding of neural dynamics from the level of individual neurons to entire brain circuits. However, neural responses may vary due to prior experience, internal states, or stochastic factors, thus generating the need for methods that can assess neural function across many individuals at once. Whereas most recording techniques examine a single animal at a time, we describe the use of wide-field microscopy to scale up neuronal recordings to dozens of Caenorhabditis elegans or other sub-millimeter-scale organisms at once. Open-source hardware and software allow great flexibility in programming fully automated experiments that control the intensity and timing of various stimulus types, including chemical, optical, mechanical, thermal, and electromagnetic stimuli. In particular, microfluidic flow devices provide precise, repeatable, and quantitative control of chemosensory stimuli with sub-second time resolution. The NeuroTracker semi-automated data analysis pipeline then extracts individual and population-wide neural responses to uncover functional changes in neural excitability and dynamics. This paper presents examples of measuring neuronal adaptation, temporal inhibition, and stimulus crosstalk. These techniques increase the precision and repeatability of stimulation, allow the exploration of population variability, and are generalizable to other dynamic fluorescent signals in small biosystems from cells and organoids to whole organisms and plants.

We present a method for the flexible chemical and multimodal stimulation and recording of simultaneous neural activity from many Caenorhabditis elegans worms. This method uses microfluidics, open-source hardware and software, and supervised automated data analysis to enable the measurement of neuronal phenomena such as adaptation, temporal inhibition, and stimulus crosstalk.

Fluorescent genetically encoded calcium indicators have contributed greatly to our understanding of neural dynamics from the level of individual neurons ...