Impact of the recording bandwidth on the electroretinogram

Previous investigators have suggested using a recording bandwidth of 100 to 1000 Hz to selectively amplify the oscillatory potentials (OPs) of the electroretinogram (ERG). The data reported in this article do not support this recommendation. Comparisons between the usual broadband (1- to 1000-Hz) ERG and that recorded with a narrower bandwidth (100 to 1000 Hz) indicate that the two ERGs have the same temporal features. The only differences noted are in amplitude and configuration, and these filter-induced modifications are predictable. The 100- to 1000-Hz ERG thus appears more like a low-voltage version of the 1- to 1000-Hz one than a recording with selective amplification of some hidden high-frequency subcomponents. A novel interpretation of ERG-wave synthesis that could account for these findings is suggested.