Abstract
Abstract: :
Purpose: To determine the normal properties of the mouse pattern electroretinogram (PERG) as a framework to investigate pathophysiological changes in mouse models of disease involving retinal ganglion cells. Methods: Corneal PERGs were recorded in young adult (3 month old) and immature (15-18 days old) anesthetized (Avertin) C57BL/6J mice in response to alternating gratings of different spatial and temporal frequencies, contrast and mean luminance. The stimulus covered a squared retinal area of approximately 50 deg side centered on the projection of the undilated pupil. Body temperature was maintained at 37 deg C with a heating pad. Results: The PERG amplitude increased almost linearly with increasing contrast (range 35-100%) and increasing mean luminance (0.5-50 cd/m2). The temporal resolution was about 12 Hz (24 reversal/s). Transient PERG waveforms to high-contrast (95%), high luminance (50 cd/m2) reversing (1 Hz) gratings consisted typically of a negative (N1)-positive (P1)-negative (N2) complex. At low spatial frequency (0.05 c/deg) the average peak latencies for adult mice were: N1=48 ms, P1 = 88 ms, N2= 214, and those of immature mice were: N1=64, P1=125, N2=264 ms. The PERG amplitude decreased with increasing spatial frequency. The average spatial resolution, as measured by extrapolating the PERG amplitude to 0 V, was about 0.6 c/deg for adult mice and 0.25 c/deg for immature mice. Conclusions: The waveform of transient mouse PERG is qualitatively similar to, albeit slower than, that of primate PERG. In both immature and adult mice, the PERG spatial resolution corresponds to the visual acuity measured with VEPs (Cell 1999, 98: 739-755). The luminance dependence of the PERG suggests that the response is primarily cone-driven.
Keywords: animal model • electrophysiology: non-clinical • ganglion cells