The A‐wave of the Human Electroretinogram During the Course of Dark Adaptation

Algvere, Peep

doi:10.1111/j.1755-3768.1967.tb06542.x

Cited by 9 publications

(8 citation statements)

References 39 publications

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“…The finding of a split a-wave consisting of a small initial (a,) and a prominent later (a,) component in 5/9 subjects is consistent with earlier observations (Armington et al 1952;Algvere 1967;Brunette 1972). The finding that the a,-wave regained its amplitude to the pre-test level earlier than the a,-wave (Table 1) supports the idea that the two a-waves have different physiological origins.…”

Section: The Erg Patternsupporting

confidence: 92%

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Receptor and neural visual readaptation after exposure to colored flash

Persson

Söderberg

Tengroth

1995

Acta Ophthalmologica Scandinavica

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The time needed to recover optokinetic nystagmus or electroretinography complexes after a glare inducing flash was measured to study the receptor and neural visual readaptation. Electroretinographs and optokinetic nystagmus were evoked with low intensity stimuli. The light from a flash tube was filtered with an interference filter (Tmax = 536 or 622 nm) and evenly distributed into a Goldmann hemisphere observed by the subject. The Recovery of the amplitude of the a-wave of the electroretinography is quicker than the recovery of optokinetic nystagmus after a low intensity glare inducing flash. The recovery time was shorter for a red than for a green flash of equivalent dose for both recovery modalities. The time difference between electroretinography a-wave and optokinetic nystagmus recovery was the same and independent of glare inducing flash wavelength. The recovery of the amplitude of the a-wave of the electroretinography was quicker than the recovery of optokinetic nystagmus after a low intensity glare inducing flash. This time difference between the recovery modalities may in part be due to the difference between the physiological stimuli used, but it is believed that most of the time difference is because the recovery of optokinetic nystagmus monitors more of the afferent visual pathway with complex post receptor neural mechanisms than the recovery of the a-wave.

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Section: The Erg Patternsupporting

confidence: 92%

“…The lack of double a-wave in 4/9 subjects may have occurred because the intensity of the ERG stimulus was so low that only the scotopic component appeared (Algvere 1967). It is likely that the single a-wave expresses scotopic properties similar to those for the a,-wave (Algvere 1967).…”

Section: The Erg Patternmentioning

confidence: 98%

Receptor and neural visual readaptation after exposure to colored flash

Persson

Söderberg

Tengroth

1995

Acta Ophthalmologica Scandinavica

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“…The stimulus-response curve for the a-wave is nearly linear for quite a considerable range (Armington, Johnson & Riggs 1952, Bornschein & Goodman 1957, Algvere 1967). In the present study subsequent increments of the logarithm of intensity produce, within a range of a few log units, a linear increase of the amplitude of the a-wave, even though the stimulus flashes were delivered at an interval of 30 seconds.…”

Section: Discussionmentioning

confidence: 99%

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

Wachtmeister

1973

Acta Ophthalmologica

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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

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“…Bornschein & Goodman (1957) were the first to suggest that a double peaked a-wave was caused by intrusion of the oscillatory potentials (OPs). This line was followed by Algvere (1967) and Brunette (1971) who studied the effects of light and dark adaptation on the double peaked a-wave. A relationship between the OPs and the double peaked a-wave has been disputed (Speros 8c Price 1981), and a correlation between the appearance of the oscillations and a split a-wave during postnatal development in the rabbit and the rat has been denied (Takahashi et al 1979).…”

mentioning

confidence: 95%

“…Therefore, in the present investigation the interference of the OPs with the a-wave was more closely analyzed by studying the postnatal development of a , and a, and their relations to the oscillations. Relatively extreme scotopic conditions were chosen since maximal amplitudes of the a-waves as well as those of the immature OPs are obtained during such conditions (Algvere 1967;Brunette 1972;el Azazi & Wachtmeister 1990, 1991b).…”

mentioning

confidence: 99%

The postnatal development of the oscillatory potentials of the electroretinogram. V. Relation to the double peaked a‐wave

Azazi

Wachtmeister

1993

Acta Ophthalmologica

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The postnatal development of the double peaked a-wave and its relation to the oscillatory potentials of the rat electroretinogram was studied. The split a-wave appeared one day later than the first oscillatory activity. The appearance and maturation of the positivity between the two a-waves (a-hump) was found to be similar to that of the first oscillatory potential, and the development of the second a-wave showed similarities to that of the second oscillatory potential. Thus, we conclude that the double peaked a-wave is closely related to the appearance of the two first oscillatory potential. Secondly, the division of the a-wave in the immature animal may be caused by the intrusion of the first oscillatory potential. Thirdly, the presence of a split a-wave before spontaneous opening of the lid seems to indicate a state of comparatively progressed maturity of neuronal adaptation.

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The A‐wave of the Human Electroretinogram During the Course of Dark Adaptation

Cited by 9 publications

References 39 publications

Receptor and neural visual readaptation after exposure to colored flash

Receptor and neural visual readaptation after exposure to colored flash

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

The postnatal development of the oscillatory potentials of the electroretinogram. V. Relation to the double peaked a‐wave

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