Post-photoreceptoral activity dominates primate photopic 32-Hz ERG for sine-, square-, and pulsed stimuli.

摘要: Purpose To evaluate the relative contributions of photoreceptors and postphotoreceptoral activity to primate 32-Hz flicker electroretinogram (ERG) elicited by sine-wave, square-wave, pulse stimuli. Methods Flicker ERGs were evoked from four adult rhesus (Macaca mulatta) monkeys using 4-ms trains xenon photostrobe All stimuli had time-averaged luminance 2.11 log cd/m(2) presented on a 1.63-log white background. Intravitreal injections DL-2-amino-4-phosphonobutyric acid (APB) cis-2,3-piperidinedicarboxylic (PDA) given block ON- OFF-bipolar cells, respectively. Results harmonic analysis showed that fundamental frequency component provided nearly 75% sine-wave square-wave versus 63% for only 49% strobe flicker. Strobe-flicker responses contained greatest contribution higher components. Removing ON with APB increased component's amplitudes more than 30% but lesser effect pulses When cone isolated synaptic blockade APB+PDA, amplitude was reduced less 20% control all Postsynaptic OFF components characterized phase vectors, gave large difference (138 degrees ) between components, which resulted in greater response self-cancellation train (121 difference) or (118 ). Conclusions The major decrease after photoreceptor implicates component, regardless stimulus type. Sine-wave produced larger differences OFF-pathway thereby causing complete revealing slightly directly these pulsed direct always small, however, clinical point is ERG do not provide an unambiguous assessment any