On the Oscillatory Potentials of the Human Electroretinogram in Light and Dark Adaptation

Abstract

The thresholds and the relation to stimulus intensity of the oscillatory potentials and the slow potentials (a-and b-wave) of the human ERG were studied on adaptation to a steady background of different intensities. The total energy and dominant frequency of the oscillatory potentials were calculated by a combined impulse response and Fourier analysis when different intensity of stimulus light was used on adaptation to a maximal background illumination (about 1.5 X 103 photopic cd/m2). The curve of incremental thresholds of the oscillatory potentials shows a flat range on exposure t o background light below 1 cdim2 (the level of adaptation, at which the Purkinje shift of the b-wave occurs) before rising along a linear section. The sensitivity of the oscillatory potentials declines on adaptation to bright background illumination when the sensitivity of the cones is higher than that of the rods.The linear section of log d I (incremental threshold) vs log I (background light) does not obey the Weber-Fechner law [log d I = K log (I + ID)] but will approach Barlow's square root formula [log dI = K log (I + ID) '/PI and the line has a slope of 0.33. There is, as expected, no sign of saturation, i. e. rapid decrease in sensitivity of the oscillatory potentials on adaptation to the brightest background illumination used. Oscillatory potentials recorded just at threshold have a high frequency (about 160 Hz), but the frequency decreases (to around 120 Hz) with

Wavelet analysis reveals dynamics of rat oscillatory potentials

“…The amplitude response of Morlet wavelets found OPs occurring between 25 and 150 ms after stimulus onset, with frequencies in the 70-130 Hz frequency band. Averaged OP data showed trends in OP amplitude and timing that are consistent with previous findings Lachapelle et al, 1991;Wachtmeister, 1972). However, there are changes in amplitude and timing of peak OP that are not characterised by a simple function of flash exposure.…”

The postnatal development of the oscillatory potentials of the electroretinogram II. Photopic characteristics

“…The oscillatory potentials (OPs) of the electrore-6 tinogram (ERG) reflect rapid adaptational changes and represent neuronal activity in the inner part of the retina (Algvere & Westbeck 1972;Wachtmeister 1972;Wachtmeister & Dowling 1978;Heynen et al 1985). Recently it has been reported that the postnatal development of the OPs generated during relatively more photopic conditions is slower compared to the OPs induced during relatively more scotopic conditions (el Azazi 8c Wachtmeister 1990).…”

Oscillatory potentials with repeated-flash electroretinography

“…Many investigators have studied differences in OPs recorded under either scotopic or photopic conditions, [16][17][18][19][29][30][31][32][33] recorded in response to light stimuli of various colors, 28,[34][35][36] or by using various locations of the active electrode. 37 The fi ndings of some of these studies 18,32,36 suggest that O1 and O2 are generated mostly by cone systems and O3 and O4 mostly by rod systems.…”

“…[16][17][18][19] The aim of this paper is to examine the ways in which retinal adaptation infl uences the behavior of OPs using repeated-fl ash stimuli.…”