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All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
1. Co-localized EEG/LFP Setup
<ol>
	<li>Clean and dry the skull surrounding the burr hole using a cotton swab.</li>
	<li>Carefully place the conductive EEG paste on one flat side of an EEG spider electrode. Leave a small hole clear of the EEG paste on the spider electrode to allow a multi-laminar microelectrode to pass through the hole without contacting the paste and the spider electrode. This prevents electrical contact between the EEG electrode and the microelectrode.</li>
	<li>Align the spider electrode to the burr hole in the skull, with the EEG paste facing the skull.</li>
	<li>Carefully press the spider electrode onto the skull, making firm contact with the skull via the EEG paste. Remove any paste obscuring the burr hole using a needle on a syringe.</li>
	<li>Remove excessive EEG paste beyond the periphery of the spider electrode so that the contact between the spider electrode and the skull is spatially constrained to the size of the electrode (Figure 1B).</li>
	<li>Smear EEG paste onto the reference electrode for the EEG and place it securely inside the incision at the back of the rat&#8217;s neck.</li>
	<li>Connect the EEG electrodes to the preamplifier via a passive signal splitter for low impedance signals (Figure 2). Make sure the impedance of the spider electrode is below 5 k&#937;. If it is not, check that the EEG paste is in good contact with the skull and the electrode is firmly pressed to the EEG paste. Add more EEG paste if necessary.</li>
	<li>Mount a micromanipulator arm on the stereotaxic frame. Connect a linear 16-channel microelectrode (100 &#181;m spacing, area of each site 177 &#181;m2) to a 16-channel acute headstage clipped securely onto the micromanipulator arm.</li>
	<li>Smear EEG paste onto the reference electrodes for the EEG and microelectrode, then securely place them inside the incision (Figure 1A).</li>
	<li>Adjust the angle of the micromanipulator arm so that the microelectrode is perpendicular to the cortical surface. This angle is normally between 25-35 &#176;.</li>
	<li>Lower the microelectrode under a microscope by turning the micromanipulator knobs so that the tip of the microelectrode is aimed at the tiny opening at the bottom of the burr hole until the uppermost electrode just penetrates the cortical surface. Care must be taken to avoid forcing the microelectrode onto the surface of the dura as this would break the electrode.</li>
	<li>Couple the 16-channel microelectrode to a preamplifier connected to a data acquisition unit via a fiber optic cable (Figure 2).</li>
	<li>Turn on the preamplifier, the data acquisition unit, and the computer connected to the unit. Turn on the stimulator box.</li>
	<li>Insert the microelectrode normally to the cortical surface by slowly turning the z-axis knob of the micromanipulator to a depth of 1,500 &#181;m.</li>
	<li>Micro-adjust the depth by applying a train of stimulus to the whisker pad and observing the 16-channel evoked LFP on a PC monitor using the software of the data acquisition unit installed on the PC. Carefully turn the z-axis knob on the micromanipulator until the highest amplitude of the evoked LFP occurs around channel 7 (as this coincides with layer IV in the cortex). 
	NOTE: Ipsi-lateral EEG electrode setup: For some experiments, a second spider electrode was placed on the ipsi-lateral side of the intact skull above the barrel cortex. This setup allowed bilateral EEG recording during the resting state to investigate the effect of the burr hole on the EEG signal. 
	NOTE: The surgical procedure to set up the EEG electrode is identical to that described above, except the temporalis muscle on each side of the head was carefully separated from the skull, sutured back and tied securely to the corresponding side of the stereotaxic frame. 
	NOTE: The concurrent EEG/LFP setup is also identical to that described above, with an additional step that a second spider electrode is loaded with the EEG paste, then pressed firmly to the skull above the ipsi-lateral barrel cortex.</li>
</ol>

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Female Lister Hood rats</td>
			<td>Charles Rivers</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Spider electrode</td>
			<td>Unimed Electrode Supplies Ltd</td>
			<td>SCS24-426</td>
			<td></td>
		</tr>
		<tr>
			<td>EEG paste: Ten20</td>
			<td>Unimed Electrode Supplies Ltd</td>
			<td>10-20-S</td>
			<td></td>
		</tr>
		<tr>
			<td>Stereotaxic holder with dual micromanipulator arms: Dual Manipulator Stereotaxic Frame with 18&#176; Ear Bars</td>
			<td>WPI (World Precision Instruments)</td>
			<td>502603</td>
			<td></td>
		</tr>
		<tr>
			<td>Stainless steel stimulating electrodes</td>
			<td>PlasticsOne</td>
			<td>E363/1/SPC</td>
			<td></td>
		</tr>
		<tr>
			<td>Isolated current stimulator</td>
			<td>Made in House</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>16-channel micro-electrode, 100 &#956;m spacing, area of each site 177 &#956;m2</td>
			<td>NeuroNexus</td>
			<td>A1x16-10mm-100-177-A16</td>
			<td></td>
		</tr>
		<tr>
			<td>16-channel acute headstage</td>
			<td>Tucker David Technologies Inc., TDT</td>
			<td>RA16AC-Z</td>
			<td></td>
		</tr>
		<tr>
			<td>Pre-Amplifier: Z-Series 64-Channel Neuro-Digitizing Preamp</td>
			<td>TDT</td>
			<td>PZ5-64</td>
			<td></td>
		</tr>
		<tr>
			<td>Passive signal splitter: 32-Channel Splitter Box for PZ5</td>
			<td>TDT</td>
			<td>S-BOX_PZ5</td>
			<td></td>
		</tr>
		<tr>
			<td>Data acquisition unit: RZ2 BioAmp Processor. Z-Series 4-DSP ultra high performance processor</td>
			<td>TDT</td>
			<td>RZ2-4</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane&#160;</td>
			<td>National Vet Services Limited&#160;</td>
			<td>50878</td>
			<td></td>
		</tr>
		<tr>
			<td>Small animal isoflurane anaesthetic system</td>
			<td>WPI&#160;</td>
			<td>EZ-B800A</td>
			<td></td>
		</tr>
		<tr>
			<td>Thermostatic heating pad: Rat Blanket System 230V</td>
			<td>Harvard Apparatus UK&#160;</td>
			<td>50-7221-F</td>
			<td></td>
		</tr>
		<tr>
			<td>Ophthalmic ointment: Optixcare eye lube</td>
			<td>Viovet&#160;</td>
			<td>203865</td>
			<td></td>
		</tr>
		<tr>
			<td>Faraday cage&#160;</td>
			<td>Newport Corporation&#160;</td>
			<td>VIS-FDC-3600</td>
			<td></td>
		</tr>
		<tr>
			<td>Vibration isolation workstation: Vision IsoStation</td>
			<td>Newport Corporation&#160;</td>
			<td>M-VIS3660-RG4-325A</td>
			<td></td>
		</tr>
		<tr>
			<td>Oximeter Control Unit and sensor: 
			MouseOxPlus, Starr Life Sciences 
			Corp.</td>
			<td>WPI&#160;</td>
			<td>O15001</td>
			<td></td>
		</tr>
		<tr>
			<td>Transparent soft nose cone: Microflex Non-Rebreathing Unit with a Rat Nosecone</td>
			<td>WPI&#160;</td>
			<td>EZ-103A</td>
			<td></td>
		</tr>
	</tbody>
</table>

concurrent electroencephalographic and local field potential recordings in an anesthetized rat

Source: Kang, S., et al. <a href="https://app-jove-com.remotexs.ntu.edu.sg/v/56447">Concurrent Recording of Co-localized Electroencephalography and Local Field Potential in Rodent.</a> J. Vis. Exp. (2017).
This video demonstrates the procedure for concurrent recordings of co-localized electroencephalography (EEG) and local field potentials (LFPs) in an anesthetized rat. The process involves preparing the rat and attaching stimulating electrodes to its whisker pads. An EEG spider electrode is placed on the rat&#39;s skull for surface EEG measurements. At the same time, a multi-channel microelectrode is inserted into a specific brain region through a burr hole in the skull to record neural activity from a localized brain area.

<img alt="Figure 1" src="/files/ftp_upload/22837/22837_Figure1.jpg" /> 
Figure 1: General setup for concurrent EEG/LFP recording. (A) The setup consists of a modified nose cone for ease of whisker pad stimulation under isoflurane anesthesia, two stimulating electrodes inserted into the whisker pad, a spider electrode positioned on the skull above the barrel cortex contra-lateral to the stimulating electrodes, a multi-channel microelectrode inserted into the barrel cortex through the spider electrode, and reference electrodes placed inside an incision at the back of the rat&#39;s neck. (B) A view through the microscope of the spider electrode securely positioned onto the skull by EEG paste. The microelectrode is inserted into a burr hole drilled into the skull under the spider electrode. The scalp is held back by surgical thread (suture) tied to the stereotaxic frame.
<img alt="Figure 2" src="/files/ftp_upload/22837/22837_Figure2.jpg" /> 
Figure 2. A signal flow diagram. The rat is placed inside a Faraday cage. The stimulating electrodes receive commands from the stimulator box controlled by the Data Acquisition Unit through its software installed on a PC. The neural signal recorded by the microelectrode is transmitted to a pre-amplifier inside the Faraday cage. The neural signal recorded by the EEG probe is transmitted to the pre-amplifier through a signal splitter. The pre-amplifier is connected to the Data Acquisition Unit outside the Faraday cage via a fiber optic cable. The neural data are then stored on a local drive on the PC, while they can also be displayed on a PC monitor. A mobile small animal isoflurane system administers isoflurane from outside the Faraday cage.

Concurrent Electroencephalographic and Local Field Potential Recordings in an Anesthetized Rat

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

Secure an anesthetized rat to a stereotaxic frame with its skull exposed.
The rat has a burr hole in the skull with the dura pierced, a neck incision, and stimulating electrodes attached to its whisker pads.
Fix an electroencephalogram, or EEG, spider electrode smeared with conductive paste on the skull, keeping the burr hole clear.
The spider electrode measures surface EEG, reflecting overall neuronal activity from the cortical area beneath it. 
Mount a linear multi-channel microelectrode onto a micromanipulator.
Insert the microelectrode into the cerebral cortex through the burr hole to a depth of 1500 micrometers.
The microelectrode measures local field potential, or LFP, reflecting cortical neuronal activity.
Place the EEG and LFP reference electrodes inside the neck incision.
Connect the recording and reference electrodes to a preamplifier linked to a data acquisition unit.
Apply electrical stimuli to the whisker pads and adjust the microelectrode depth to maximize the evoked LFP amplitude. Record the co-localized EEG and LFP signals.

concurrent-electroencephalographic-local-field-potential-recordings

Nanyang Technological University

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JoVE Encyclopedia of Experiments

Neuroscience

Neurophysiology

Electrophysiology Techniques

42 Views. Source: Kang, S., et al. Concurrent Recording of Co-localized Electroencephalography and Local Field Potential in Rodent. J. Vis. Exp. (2017). This video demonstrates the procedure for concurrent recordings of co-localized electroencephalography (EEG) and local field potentials (LFPs) in an anesthetized rat. The process involves preparing the rat and attaching stimulating electrodes to its whisker pads. An EEG spider electrode is placed on the rat's skull for surface EEG measurements. At th...

Video: Concurrent Electroencephalographic and Local Field Potential Recordings in an Anesthetized Rat - Concept

Acute In Vivo Electrophysiological Recordings of Local Field Potentials and Multi-unit Activity from the Hyperdirect Pathway in Anesthetized Rats

Converging evidence shows that many neuropsychiatric diseases should be understood as disorders of large-scale neuronal networks. To better understand the pathophysiological basis of these diseases, it is necessary to precisely characterize in which way the processing of information is disturbed between the different neuronal parts of the circuit. Using extracellular in vivo electrophysiological recordings, it is possible to accurately delineate neuronal activity within a neuronal network. The application of this method has several advantages over alternative techniques, e.g., functional magnetic resonance imaging and calcium imaging, as it allows a unique temporal and spatial resolution and does not rely on genetically engineered organisms. However, the use of extracellular in vivo recordings is limited since it is an invasive technique that cannot be universally applied. In this article, a simple and easy to use method is presented with which it is possible to simultaneously record extracellular potentials such as local field potentials and multiunit activity at multiple sites of a network. It is detailed how a precise targeting of subcortical nuclei can be achieved using a combination of stereotactic surgery and online analysis of multi-unit recordings. Thus, it is demonstrated, how a complete network such as the hyperdirect cortico-basal ganglia loop can be studied in anesthetized animals in vivo.

Acute In Vivo Electrophysiological Recordings of Local Field Potentials and Multi-unit Activity from the Hyperdirect Pathway in Anesthetized Rats

In this study, the methodology is presented on how to perform multi-site in vivo electrophysiological recordings from the hyperdirect pathway under urethane anesthesia.

Converging evidence shows that many neuropsychiatric diseases should be understood as disorders of large-scale neuronal networks. To better understand the ...

JoVE Journal

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 Local Field Potential Microelectrodes for in vivo Recordings from Multiple Brain Structures Simultaneously

Researchers often need to record local field potentials (LFPs) simultaneously from several brain structures. Recording from multiple desired brain regions requires different microelectrode designs, but commercially available microelectrode arrays often do not offer such flexibility. Here, the present protocol outlines the straightforward design of custom-made microelectrode arrays to record LFPs from multiple brain structures simultaneously at different depths. This work describes the construction of the bilateral cortical, striatal, ventrolateral thalamic, and nigral microelectrodes as an example. The outlined design principle offers flexibility, and the microelectrodes can be modified and customized to record LFPs from any structure by calculating stereotaxic coordinates and quickly changing the construction accordingly to target different brain regions in either freely moving or anesthetized mice. The microelectrode assembly requires standard tools and supplies. These custom microelectrode arrays allow investigators to easily design microelectrode arrays in any configuration to track neuronal activity, providing LFP recordings with millisecond resolution.

Construction of Local Field Potential Microelectrodes for in vivo Recordings from Multiple Brain Structures Simultaneously

The present protocol describes the construction of custom-made microelectrode arrays to record local field potentials in vivo from multiple brain structures simultaneously.

Researchers often need to record local field potentials (LFPs) simultaneously from several brain structures. Recording from multiple desired brain regions ...

Concurrent Electroencephalographic and Local Field Potential Recordings in an Anesthetized Rat

Transcript

Concurrent Electroencephalographic and Local Field Potential Recordings in an Anesthetized Rat

Acute In Vivo Electrophysiological Recordings of Local Field Potentials and Multi-unit Activity from the Hyperdirect Pathway in Anesthetized Rats

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

Construction of Local Field Potential Microelectrodes for in vivo Recordings from Multiple Brain Structures Simultaneously