Stimulus Duration and the Oscillatory Potentials of the Human Electroretinogram

Abstract

The effect of duration of stimulus light on the threshold of oscillatory and the slow (a-and b-wave) potentials of the human ERG were assessed on light adaptation to light stimuli. On weak light adaptation induced by stimuli given at 2 min intervals there was a temporal summation of the oscillatory potentials over a range of at least 2 log units (4 msec-400msec). The threshold of the a-wave and bwave was dependent on duration up to a critical duration of about 40 msec. On strong light adaptation by repetitive light stimulation with 15 sec intervals the oscillations were determined by intensity alone over a range of 2 log units. The a-wave revealed a similar behaviour, whereas the bwave integrated stimuli in the temporal domain up to about 10 msec.Of main importance; the results provide evidence which is suggestive of temporal integration and discrimination being independently governed by the neurons (probably at the inner plexiform layer), which generate the oscillatory potentials.

Spatial characteristics of the oscillatory potentials of the electroretinogram

“…For example, the laminar profile, current distribution and chemical properties of the OPs are separate from that of the slow potentials (Wachtmeister & Dowling 1978;Wachtmeister 1980Wachtmeister , 1981a. Their temporal summation has also been investigated and found to deviate from that the main ERG components (Wachtmeister 1974). However, the spatial integration of the OPs is unknown.…”