Name: Video: Recording of Visual Evoked Potentials via the Skull Electrodes in a Rat Model - Concept
Uploaded: 2024-10-31T13:46:35.000+00:00
Duration: 1 min 19 s
Description: 59 Views. Source: You, Y., et al. Visual Evoked Potential Recording in a Rat Model of Experimental Optic Nerve Demyelination. J. Vis. Exp. (2015). This video demonstrates the process of measuring visual evoked potentials or VEPs in a dark-adapted, anesthetized rat with pre-implanted skull electrodes, which record the electrical signals from the brain's visual cortex in response to light stimuli.

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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. VEP Electrode Implantation
<ol>
	<li>Anesthetize the animal with an intraperitoneal injection of ketamine (75 mg/kg) and medetomidine (0.5 mg/kg). 
	NOTE: Following induction of anesthesia, observe the withdrawal reflexes (pinch test, corneal and palpebral reflex, etc.) and their absence as an indication to begin surgery. Continually monitor animals throughout the surgery and administer additional anesthetic drugs (10% of the initial ketamine dose per top-up) if the reflexes are present. Adult rats (&#62;12 weeks) are used in the experiments.</li>
	<li>Shave the skin of the surgical area. Place the animal on a warming pad (37 &#176;C) to maintain body temperature during the surgery. Prepare skin through topical application of povidone-iodine. Apply surgical draping. Apply topical ophthalmic ointment to prevent corneal dryness under general anesthesia. Maintain asepsis by using sterile instruments.</li>
	<li>Make a longitudinal skin incision on the midline of the head skin. Clear the connective tissue to achieve good exposure of the skull.</li>
	<li>Carefully drill small burr holes manually using a micro hand drill at 7 mm behind the bregma and 3 mm lateral to the midline.</li>
	<li>Implant screw electrodes through the skull into the cortex (area 17), penetrating the cortex to a depth of approximately 0.5 mm. Implant a reference screw electrode on the midline 3 mm rostral to the bregma. Apply dental cement to encase and fix the screws (not always required).</li>
	<li>Suture the skin of the head, administer antibiotic ointment onto the skin, and allow the animal to recover from anesthesia on a warming pad. 
	Note: Alternatively, electrodes can be left exposed so that skin doesn&#39;t need to be reopened in each recording. Immediately upon cessation of surgery but prior to anesthetic recovery, administer a non-steroidal anti-inflammatory drug (NSAID) (if not administered pre-operatively) or an opioid analgesic. Monitor the animals constantly until they fully recover from the anesthetic and are ambulatory.</li>
	<li>Allow at least 1 week for the animals to recover from the surgery prior to VEP recording.</li>
</ol>
2. VEP Recording
<ol>
	<li>Anesthetize the animal and prepare the skin as 1.1 and 1.2. 
	Note: A lower dose of anesthetics can be used for electrophysiological recording (ketamine 40 mg/kg and medetomidine 0.25 mg/kg).</li>
	<li>Place the rat in a dark room and allow it to adapt to darkness for 5 - 30 min. In some cases, rats can be dark-adapted O/N for scotopic or light-adapted for photopic VEP recordings.</li>
	<li>Maintain the body temperature at 37 &#177; 0.5 &#176;C by the homoeothermic blanket system with a rectal thermometer probe.</li>
	<li>Dilate the pupils with 1.0% tropicamide eye drops. Open the skin over the skull to access the pre-placed in situ screw electrodes.</li>
	<li>Connect the screw over the contralateral visual cortex of the stimulated eye and the reference screw to the amplifier. Insert a needle electrode into the tail as the ground. Measure and maintain the electrode impedance below 5 k&#8486;.</li>
	<li>Place a mini-Ganzfeld stimulator directly on the skin around the eyelids to provide superior eye isolation. The illumination of the stimulator needs to be calibrated beforehand by a photometer.</li>
	<li>Deliver photic stimulation through light flashes 100 times at a frequency of 1 Hz, with low and high band-pass filter settings of 1 and 100 Hz, respectively. The signal sampling rate is at 5 kHz. 
	Note: Signals should be sampled at least at about 250 - 300 Hz to ensure that more than two samples are collected during each cycle.</li>
	<li>Suture the skin back and keep the animals on a warming pad to recover from anesthesia. Recording can be repeatedly recorded on individual animals to monitor functional changes over a period of time.</li>
</ol>

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Ketamine 100 mg/ml (Ketamil)</td>
			<td>Troy Laboratories</td>
			<td>AC 116</td>
			<td></td>
		</tr>
		<tr>
			<td>Medetomidine 1 mg/ml (Domitor)</td>
			<td>Pfizer</td>
			<td>sc-204073</td>
			<td></td>
		</tr>
		<tr>
			<td>Tropicamide 1.0% (Mydriacyl)</td>
			<td>Alcon</td>
			<td>sc-202371</td>
			<td></td>
		</tr>
		<tr>
			<td>Homoeothermic blanket system</td>
			<td>Harvard Apparatus</td>
			<td>NC9203819</td>
			<td></td>
		</tr>
		<tr>
			<td>Impedance meter</td>
			<td>Grass</td>
			<td>F-EZM5</td>
			<td></td>
		</tr>
		<tr>
			<td>Screw electrodes</td>
			<td>Micro Fasteners</td>
			<td>M1.0&#215;3mm Csk Slot M/T 304 S/S</td>
			<td></td>
		</tr>
		<tr>
			<td>Subdermal needle electrodes</td>
			<td>Grass</td>
			<td>F-E3M-72</td>
			<td></td>
		</tr>
		<tr>
			<td>Rapid Repair</td>
			<td>DeguDent GmbH</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Light-emitting diode</td>
			<td>Nichia</td>
			<td>NSPG300A</td>
			<td></td>
		</tr>
		<tr>
			<td>Bioamplifier</td>
			<td>CWE, Inc.</td>
			<td>BMA-400</td>
			<td></td>
		</tr>
		<tr>
			<td>CED system</td>
			<td>Cambridge Electronic Design, Ltd.</td>
			<td>Power1401</td>
			<td></td>
		</tr>
	</tbody>
</table>

recording of visual evoked potentials via the skull electrodes in a rat model

Source: You, Y., et al. <a href="https://app.jove.com/v/52934">Visual Evoked Potential Recording in a Rat Model of Experimental Optic Nerve Demyelination.</a> J. Vis. Exp. (2015).
This video demonstrates the process of measuring visual evoked potentials or VEPs in a dark-adapted, anesthetized rat with pre-implanted skull electrodes, which record the electrical signals from the brain&#39;s visual cortex in response to light stimuli.

Recording of Visual Evoked Potentials via the Skull Electrodes in a Rat Model

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

Begin with an anesthetized, dark-adapted rat. Add a drug solution to the eyes to widen the pupils.
This allows more light to reach the retina, the light-sensitive layer with photoreceptors.
Make a skull incision to expose pre-implanted recording screw electrodes in the brain&#39;s visual cortex and a reference electrode at the midline.
Connect one of the visual cortex screw electrodes and the reference electrode to an amplifier for signal recording.
Next, insert a ground electrode into the tail to reduce electrical noise.
Position a light-stimulation device over the eye on the side opposite to the connected cortex screw electrode and then deliver the light flashes.
Retinal photoreceptors detect the light and convert it into electrical signals that travel along the optic nerve and transmit to the opposite visual cortex.
In the visual cortex, the pre-implanted electrode detects these signals and produces the electrical output generated by light stimuli, termed as visual evoked potentials, or VEPs.

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59 Views. Source: You, Y., et al. Visual Evoked Potential Recording in a Rat Model of Experimental Optic Nerve Demyelination. J. Vis. Exp. (2015). This video demonstrates the process of measuring visual evoked potentials or VEPs in a dark-adapted, anesthetized rat with pre-implanted skull electrodes, which record the electrical signals from the brain's visual cortex in response to light stimuli. 

Video: Recording of Visual Evoked Potentials via the Skull Electrodes in a Rat Model - Concept

Implantation and Recording of Wireless Electroretinogram and Visual Evoked Potential in Conscious Rats

The full-field electroretinogram (ERG) and visual evoked potential (VEP) are useful tools to assess retinal and visual pathway integrity in both laboratory and clinical settings. Currently, preclinical ERG and VEP measurements are performed with anesthesia to ensure stable electrode placements. However, the very presence of anesthesia has been shown to contaminate normal physiological responses. To overcome these anesthesia confounds, we develop a novel platform to assay ERG and VEP in conscious rats. Electrodes are surgically implanted sub-conjunctivally on the eye to assay the ERG and epidurally over the visual cortex to measure the VEP. A range of amplitude and sensitivity/timing parameters are assayed for both the ERG and VEP at increasing luminous energies. The ERG and VEP signals are shown to be stable and repeatable for at least 4 weeks post surgical implantation. This ability to record ERG and VEP signals without anesthesia confounds in the preclinical setting should provide superior translation to clinical data.

We show surgical implantation and Recording procedures to measure visual electrophysiological signals from the eye (electroretinogram) and brain (visual evoked potential) in conscious rats, which is more analogous to the human condition where recordings are conducted without anesthesia confounds.

The full-field electroretinogram (ERG) and visual evoked potential (VEP) are useful tools to assess retinal and visual pathway integrity in both ...

JoVE Journal

Behavior

Simultaneous Recording of Electroretinography and Visual Evoked Potentials in Anesthetized Rats

The electroretinogram (ERG) and visual evoked potential (VEP) are commonly used to assess the integrity of the visual pathway. The ERG measures the electrical responses of the retina to light stimulation, while the VEP measures the corresponding functional integrity of the visual pathways from the retina to the primary visual cortex following the same light event. The ERG waveform can be broken down into components that reflect responses from different retinal neuronal and glial cell classes. The early components of the VEP waveform represent the integrity of the optic nerve and higher cortical centers. These recordings can be conducted in isolation or together, depending on the application. The methodology described in this paper allows simultaneous assessment of retinal and cortical visual evoked electrophysiology from both eyes and both hemispheres. This is a useful way to more comprehensively assess retinal function and the upstream effects that changes in retinal function can have on visual evoked cortical function.

This protocol describes simultaneous measurement of electroretinogram and visual evoked potentials in anesthetized rats.

The electroretinogram (ERG) and visual evoked potential (VEP) are commonly used to assess the integrity of the visual pathway. The ERG measures the ...

Objectively Assessing Sports Concussion Utilizing Visual Evoked Potentials

A portable system capable of measuring steady-state visual-evoked potentials (SSVEP) was developed to provide an objective, quantifiable method of electroencephalogram (EEG) testing following a traumatic event. In this study, the portable system was used on 65 healthy rugby players throughout a season to determine whether SSVEP are a reliable electrophysiological biomarker for concussion. Preceding the competition season, all players underwent a baseline SSVEP assessment. During the season, players were re-tested within 72 h of a match for either test-retest reliability or post-injury assessment. In the case of a medically diagnosed concussion, players were reassessed again once deemed recovered by a physician. The SSVEP system consisted of a smartphone housed in a VR-frame delivering a 15 Hz flicker stimulus, while a wireless EEG headset recorded occipital activity. Players were instructed to stare at the screen's fixation point while remaining seated and quiet. Electrodes were arranged according to the 10-20 EEG-positioning nomenclature, with O1-O2 being the recording channels while P1-P2 the references and bias, respectively. All EEG data was processed using a Butterworth bandpass filter, Fourier transformation, and normalization to convert data for frequency analysis. Players SSVEP responses were quantified into a signal-to-noise ratio (SNR), with 15 Hz being the desired signal, and summarized into respective study groups for comparison. Concussed players were seen to have a significantly lower SNR compared to their baseline; however, post-recovery, their SNR was not significantly different from the baseline. Test-retest indicated high device reliability for the portable system. An improved portable SSVEP system was also validated against an established EEG amplifier to ensure the investigative design is capable of obtaining research quality EEG measurements. This is the first study to identify differences in SSVEP responses in amateur athletes following a concussion and indicates the potential for SSVEP as an aid in concussion assessment and management.

A portable system capable of measuring steady-state visual-evoked potentials was developed and trialed on 65 amateur rugby players over 18 weeks to investigate SSVEP as a potential electrophysiological biomarker for concussion. Players' baselines were measured pre-season, with retesting for reliability, concussion, and recovery assessment being conducted within controlled time-periods, respectively.

Recording of Visual Evoked Potentials via the Skull Electrodes in a Rat Model

Transcript

Recording of Visual Evoked Potentials via the Skull Electrodes in a Rat Model

Implantation and Recording of Wireless Electroretinogram and Visual Evoked Potential in Conscious Rats

Simultaneous Recording of Electroretinography and Visual Evoked Potentials in Anesthetized Rats

Objectively Assessing Sports Concussion Utilizing Visual Evoked Potentials