Visual evoked potentials can be reliably recorded using noninvasive epidermal electrodes in the anesthetized rat

Area of Science:

• Neuroscience
• Ophthalmology
• Biomedical Engineering

Background:

• Visual evoked potentials (VEPs) are crucial for assessing visual pathway function in humans and animals.
• Traditional epidural screw electrodes are invasive and used in preclinical VEP research.
• A noninvasive clinical VEP technique using epidermal cup electrodes was investigated for preclinical use.

Purpose of the Study:

• To evaluate the feasibility of using noninvasive epidermal cup electrodes for VEP recording in a preclinical setting.
• To compare the efficacy of epidermal cup electrodes with traditional epidural screw electrodes for VEP acquisition.

Main Methods:

• Monocular flash VEPs were recorded weekly for six weeks in dark Agouti rats under sevoflurane anesthesia.
• Two groups of rats were used: one with implanted epidural screws and another with epidermal Ag/AgCl cups.
• VEPs were recorded bilaterally using both techniques.

Main Results:

• VEP traces from both methods were morphologically similar.
• No significant differences in the latency of the main visual component were observed between screw-recorded VEPs (sVEPs) and cup-recorded VEPs (cVEPs).
• Epidermal cups yielded significantly lower amplitude values than epidural screws, but both methods showed stable and repeatable measurements over time, with epidermal cups showing slightly better latency repeatability.

Conclusions:

• Noninvasive epidermal cup electrodes are a feasible alternative to epidural screws for preclinical VEP recording.
• This technique simplifies VEP acquisition and reduces invasiveness in animal models.
• Epidermal cups provide comparable latency and repeatability to the gold standard, offering a less invasive approach to study visual pathway conduction.