Analysis of pharmacologically isolated components of the ERG

An harmonic analysis was applied to the electroretinogram (ERG) measured in intact cat eyes in control conditions and after pharmacological isolation of the components attributed to photoreceptors (PIII) and bipolar neurons ( PII). The frequency response curves obtained in various conditions showed t hat the bandwidth of the PII component extends over a range of stimulus fre quencies higher than the bandwidth of PIII. The enhancement of the PII resp onse to stimuli of high temporal frequency suggests the presence of a frequ ency dependent gain control located either pre- and/or post-synaptically in the transmission line between the phototransductive cascade and bipolar ne urons. A possible role of these processes is to enhance relevant visual inf ormation whilst selectively attenuating low frequency signals originating i n the transductive cascade. (C) 1999 Elsevier Science Ltd. All rights reser ved.