Visual evoked potentials can be reliably recorded using noninvasive epidermal electrodes in the anesthetized rat.
PURPOSE
Visual evoked potentials (VEPs) are a powerful tool to evaluate nervous conduction along the visual pathways, both in humans and in animal models. Traditionally, epidural screw electrodes are used to record VEPs in preclinical research. Here we tested the feasibility in the preclinical setting of the same noninvasive technique used for clinical VEP acquisition, by using epidermal cup electrodes with no surgical procedures.


METHODS
Monocular flash VEPs were recorded bilaterally under sevoflurane anesthesia once a week for 6 weeks in 14 dark Agouti rats, 7 with implanted epidural screws and 7 with epidermal 6 mm Ø Ag/AgCl cups.


RESULTS
VEP traces obtained with the two techniques were morphologically comparable. There were no significant differences in latency of the main visual component between screw-recorded VEPs (sVEPs) and cup-recorded VEPs (cVEPs). Amplitude values with epidermal cups were significantly lower than those with epidural screws. Both techniques provided latencies and amplitudes which were stable over time. Furthermore, with regard to latency both methods ensured highly repeatable measurements over time, with epidermal cups even providing slightly better results. On the other hand, considering amplitudes, cVEPs and sVEPs provided fairly acceptable repeatability.


CONCLUSIONS
Epidermal cup electrodes can provide comparable results to those obtained with the "gold standard" epidural screws, while representing a simpler and less invasive technique to test nervous conduction along the visual pathways in the preclinical setting.
['Santangelo|Roberto|R|', 'Castoldi|Valerio|V|', "D'Isa|Raffaele|R|", 'Marenna|Silvia|S|', 'Huang|Su-Chun|SC|', 'Cursi|Marco|M|', 'Comi|Giancarlo|G|', 'Leocani|Letizia|L|']
D018685:Anesthetics, Inhalation D000818:Animals D004566:Electrodes D004596:Electroretinography D004817:Epidermis D005074:Evoked Potentials, Visual D005260:Female D008738:Methyl Ethers D010775:Photic Stimulation D051381:Rats D000077149:Sevoflurane D014795:Visual Pathways
Visual evoked potentials Epidural screw electrodes Epidermal cup electrodes Animal welfare Noninvasive electrophysiology Preclinical visual pathway assessment