Human photopic ON- and OFF-ERG responses elicited by square wave and sawtooth stimuli.

Abstract

In this study, the on-and off-responses elicited by luminance square wave and sawtooth stimuli at different temporal frequencies and contrasts are described quantitatively. Adding on-and off-responses reveals response asymmetries. Full-field stimuli were produced using a Ganzfeld bowl with arrays of light-emitting diodes (LEDs) as light sources. ERG responses were recorded from six normal subjects. The amplitudes and implicit times of components of the on-and off-responses and the additions were analyzed. The amplitudes of the on-, off-and addition components elicited by square wave stimuli did not depend on temporal frequency with the exception of the late negative components, which decreased with increasing temporal frequency up to 4 Hz. The amplitudes of all components elicited by sawtooth stimuli, except the P-on, decreased with increasing temporal frequency. The amplitude of all components elicited by square wave and sawtooth stimuli were positively correlated with stimulus contrast. The implicit times of the on-components to square wave stimuli and all response components to sawtooth stimuli decreased with increasing temporal frequency. Contrast had an effect on the implicit times of the N-on, P-on, P-off and P-add components elicited by square wave stimuli and the N-on, P-on, P-add and LN-on components elicited by sawtooth stimuli. The asymmetries between on-and off-responses can possibly be used to reveal inner retinal contributions and may therefore be interesting in detecting glaucomatous changes.

An asymmetric outer retinal response to drifting sawtooth gratings

“…These waveforms were also evident at 2.5 and 5 Hz for all stimuli except sine-wave and fast-ON gratings, which showed weak responses at low temporal frequencies. Consistent with the temporal sawtooth flicker literature (Alexander et al 2001;Barnes et al 2002;Dryja et al 2005;Khan et al 2005;Kremers 2013;Kremers et al 1993;Pangeni and Kremers 2013;Pangeni et al 2012;Rodrigues et al 2010;Vukmanic et al 2014) and brightness perception measures in humans (Cavanagh and Anstis 1986;Watanabe et al 1995), the DC potential shift for spatiotemporal fast-OFF sawtooth was larger than that for fast-ON sawtooth across all of the conditions tested (shaded gratings drifting at 2.5-20 Hz and shaded diamonds drifting at 5 Hz).…”

“…This finding builds on an extensive crossspecies literature demonstrating that the retinal response to temporal fast-OFF and fast-ON sawtooth is asymmetric (Alexander et al 2001;Barnes et al 2002;Dryja et al 2005;Khan et al 2005;Kremers 2013;Kremers et al 1993;Pangeni and Kremers 2013;Pangeni et al 2012;Rodrigues et al 2010;Vukmanic et al 2014). Within this temporal domain, the toad ERG response appears comparable to that of humans and monkeys, where the fast phase of fast-ON flicker generally elicits slightly larger ON-bipolar responses relative to the combined photoreceptor and OFF-bipolar response elicited by fast-OFF flicker (Alexander et al 2001;Barnes et al 2002;Khan et al 2005;Kremers 2013;Pangeni and Kremers 2013;Vukmanic et al 2014). Moreover, like in monkey (Khan et al 2005), our pharmacological dissection of the toad temporal sawtooth ERG (Fig.…”

“…sawtooth; electroretinogram; flicker; motion; spatiotemporal; brightness illusion ELECTROPHYSIOLOGICAL STUDIES of retinal ON-OFF processing have demonstrated that the response to temporally modulated sawtooth flicker is asymmetric (Alexander et al 2001;Barnes et al 2002;Dryja et al 2005;Khan et al 2005;Kremers 2013; Kremers et al 1993;Pangeni and Kremers 2013;Pangeni et al 2012;Rodrigues et al 2010;Vukmanic et al 2014). It is unknown whether such asymmetries also occur for more complex spatiotemporal sawtooth stimuli (i.e., moving sawtooth grating or diamond patterns).…”

Probing ON and OFF Retinal Pathways in Glaucoma Using Electroretinography

“…These protocols were shown to correlate with the ON- and OFF-pathways, respectively. 77 After the abrupt change in light intensity, the rapid-on stimulus generates a waveform with an initial negative peak followed by a large positive waveform. The rapid-off stimulus generates only an initial positive response.…”