Abstract
Purpose:
The mouse pattern electroretinogram (PERG), differently from the flash ERG, display strong interocular cross-talk and binocular summation (PMID: 23150622) that preclude simultaneous recording from each eye using standard techniques. Our goal was to develop a simple, reproducible method for binocular PERG recording in mice.
Methods:
The PERG was recorded from seven C57BL/6J mice 4 months old under ketamine/xylazine anesthesia using one-channel acquisition of signals recorded from subcutaneous needles (positive: snout; negative: back of the head). Pattern stimuli (gratings of 0.05 cycles/deg, 100% contrast) were generated on two LED tablets each alternating at slightly different frequencies around 1 Hz and presented separately to each eye. Independent PERG signals from each eye were retrieved using an asynchronous averaging method. PERGs were recorded in at least 3 different sessions to test repeatability.
Results:
Binocular PERG amplitude (mean 30.4 µV, SD 4.4) and latency (mean 90.6 ms, SD 7.7) were similar to those recorded from corneal electrodes and monocular stimulation. Interocular cross-talk and binocular summation were absent. The between-test coefficient of variation was, amplitude: mean 23.1 %, SD 9.8; latency: mean 11.8%, SD 6.8. The mean interocular asymmetry was, amplitude: 19.9 %, SD 14.8; latency: 5.44%, SD 4.6.
Conclusions:
Compared to current methods (PMID:17251473), the binocular PERG from the snout coupled with asynchronous averaging represents a substantial improvement in terms of simplicity and reproducibility. It also allows more precise, timely comparisons between the responses of the two eyes over the recording period, and overcomes limitations of corneal electrodes that interfere with invasive procedures such as intraocular injections. As the PERG is increasingly used to probe retinal ganglion cell function in mouse models of glaucoma and optic nerve disease, the binocular asynchronous PERG represents an advantageous opportunity.
Keywords: 510 electroretinography: non-clinical •
531 ganglion cells •
629 optic nerve