Spatial-frequency-tuned attenuation and enhancement of the steady-state VEP by grating adaptation

Suter, Steve; Armstrong, Colin; Suter, Penelope S.; Powers, Justina

doi:10.1016/0042-6989(91)90042-4

Cited by 17 publications

(17 citation statements)

References 37 publications

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“…3). This is in accordance with previous studies (Mecacci & Spinally, 1976;Suter et al, 1991;Heinrich & Bach, 2002). Interestingly, when adapting at 5 cpd and testing at 0.5 cpd, an enhancement by 26% was found (Fig.…”

Section: Vepsupporting

confidence: 94%

“…3, top right). Such effects have been reported earlier by Suter et al (1991): They found an amplitude reduction when testing at the adapting spatial frequency, which turned into an amplitude enhancement when the spatial frequencies differed by more than 1 octave. This could be explained by cortical inhibition between spatial-frequency channels, known from single-cell recordings in cat (DeValois & Tootell, 1983).…”

Section: Vepmentioning

confidence: 54%

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Contrast adaptation in retinal and cortical evoked potentials: No adaptation to low spatial frequencies

Heinrich

Bach

2002

Vis Neurosci

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Contrast adaptation occurs in both the retina and the cortex. Defining its spatial dependence is crucial for understanding its potential roles. We thus asked to what degree contrast adaptation depends on spatial frequency, including cross-adaptation. Measuring the pattern electroretinogram (PERG) and the visual evoked potential (VEP) allowed separating retinal and cortical contributions. In ten subjects we recorded simultaneous PERGs and VEPs. Test stimuli were sinusoidal gratings of 98% contrast with spatial frequencies of 0.5 or 5.0 cpd, phase reversing at 17 reversals/s. Adaptation was controlled by prolonged presentation of these test stimuli or homogenous gray fields of the same luminance. When adaptation and test frequency were identical, we observed significant contrast adaptation only at 5 cpd: an amplitude reduction in the PERG (-22%) and VEP (-58%), and an effective reduction of latency in the PERG (-0.95 ms). When adapting at 5 cpd and testing at 0.5 cpd, the opposite effect was observed: enhancement of VEP amplitude by +26% and increase in effective PERG latency by + 1.35 ms. When adapting at 0.5 cpd and testing at 5 cpd, there was no significant amplitude change in PERG and VEP, but a small effective PERG latency increase of +0.65 ms. The 0.5-cpd channel was not adapted by spatial frequencies of 0.5 cpd. The adaptability of the 5-cpd channel may mediate improved detail recognition after prolonged blur. The existence of both adaptable and nonadaptable mechanisms in the retina allows for the possibility that by comparing the adaptational state of spatial-frequency channels the retina can discern between overall low contrast and defocus in emmetropization control.

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Section: Vepsupporting

confidence: 94%

Section: Vepmentioning

confidence: 54%

Contrast adaptation in retinal and cortical evoked potentials: No adaptation to low spatial frequencies

Heinrich

Bach

2002

Vis Neurosci

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“…Pharmacological removal of this inhibition enhances the response of cortical cells to coarse patterns and shifts the peak spatial frequency response in many cells toward lower spatial frequencies [12,13]. The role of inhibitory interactions in shaping the visual response to spatial (patterned) stimuli has also been demonstrated with psychophysical [14,15] and electrophysiological (VEP) data [16][17][18] in humans.…”

Section: Introductionmentioning

confidence: 92%

Epilepsy and Medication Effects on the Pattern Visual Evoked Potential*

et al. 2005

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Visual disruption in patients diagnosed with epilepsy may be attributable to either the disease itself or to the anti-epileptic drugs prescribed to control the seizures. Effects on visual function may be due to perturbations of the GABAergic neurotransmitter system, since deficits in GABAergic cortical interneurons have been hypothesized to underlie some forms of epilepsy, some anti-epileptic medications increase cortical GABA levels, and GABAergic neural circuitry plays an important role in mediating the responses of cells in the visual cortex and retina. This paper characterizes the effects of epilepsy and epilepsy medications on the visual evoked response to patterned stimuli. Steady-state visual evoked potentials (VEP) evoked by onset-offset modulation of high-contrast sine-wave stimuli were measured in 24 control and 54 epileptic patients. Comparisons of VEP spectral amplitude as a function of spatial frequency were made between controls, complex partial, and generalized epilepsy groups. The effects of the GABA-active medication valproate were compared to those of carbamezepine. The amplitude of the fundamental (F1) component of the VEP was found to be sensitive to epilepsy type. Test subjects with generalized epilepsy had F1 spatial frequency-amplitude functions with peaks shifted to lower spatial frequencies relative to controls and test subjects with complex partial epilepsy. This shift may be due to reduced intracortical inhibition in the subjects with generalized epilepsy. The second harmonic component (F2) response was sensitive to medication effects. Complex partial epilepsy patients on VPA therapies showed reduced F2 response amplitude across spatial frequencies, consistent with previous findings that showed the F2 response is sensitive to GABA-ergic effects on transient components of the VEP.

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“…For example, Blakemore and Campbell (1969) found that spatial frequency sensitivity may be suppressed not only for the frequency used for adaptation but also for spatial frequencies close to this frequency. In addition, it has been suggested that the spatial frequency sensitivity suppressed most by adaptation may be shifted away from the adaptation frequency to the nearest frequency channel of peak sensitivity (Suter et al, 1991), where it is assumed that there are only a limited number of such channels available in the visual system (e.g., Watson & Robson, 1981). It may also be possible that sensitivity to certain spatial frequencies is facilitated because of a reduction in inhibition produced by the adapted frequency (De Valois, 1977;Suter et al, 1991).…”

Section: Preliminary Assessment Of Adaptation Stimulimentioning

confidence: 99%

“…Doing exactly this, Foley and Boynton (1993) found that when the initial adaptation period lasted for 2 min, and each adaptation top-up period was separated by an interval of 2 sec (during which time experimental targets were shown), adaptation top-up periods lasting 2 sec maintained the same level of adaptation throughout the experiment. The periods used (but not normally explicitly motivated) by other researchers for the initial adaptation period and for the duration of each top-up are usually also in the order of several minutes and several seconds, respectively (e.g., Heinrich & Bach, 2002;Suter, Armstrong, Suter, & Powers, 1991).…”

Section: Adaptation Timingmentioning

confidence: 99%