Abstract
Purpose: :
Neural processing in the retina generates an electric field throughout the eye and surrounding tissue. As PERG and FERG have different retinal generators, we investigated differences in the bioelectric fields of the PERG and FERG in the mouse model.
Methods: :
PERGs and FERGs were recorded simultaneously from each eye in 18 mice (C57BL/6J, n=10, DBA/2J, n=4, DBA/1J, n=4) using corneal silver loops referenced to a subcutaneous needle on the back of the head. PERG stimuli were horizontal gratings of 0.05 cycles/deg and 100% contrast. Photopic FERG stimuli were strobe flashes superimposed on and adapting background. Stimuli were delivered either monocularly (with the non-stimulated eye occluded) or binocularly. In some experiments, TTX was injected in one eye and saline in the contralateral eye.
Results: :
Monocular PERGs were recordable from both the stimulated and the non-stimulated eye with similar amplitudes. Under binocular stimulation, the PERG amplitude was 1.7 times (SE 0.18) larger than the monocular amplitude (p<0.01). TTX injected in the stimulated eye abolished the PERG in both eyes, whereas TTX injected in the non-stimulated eye had no effect on PERG of both eyes. Monocular FERGs were recordable from the stimulated eye only. Binocular and monocular FERGs had the same amplitudes.
Conclusions: :
PERG and FERG generate different bioelectric fields in the mouse. The FERG signal does not propagate to the non-stimulated eye as expected, whereas the PERG displays obvious cross-talk, including summation under binocular stimulation. Results are relevant for better understanding of PERG generators and have technical implications for binocular recordings.
Keywords: ganglion cells • electroretinography: non-clinical • retinal connections, networks, circuitry