Binocular summation improves performance to defocus-induced blur

Electroencephalography and Clinical Neurophysiology/Evoked Potentials Section, 1996

We recorded the monocular and binocular VEPs to the alternation of sinusoidal gratings in order to evaluate the binocular interaction in each component of transient and steady-state VEPs in 13 normal subjects. Three spatial frequencies (1.3, 2.6 and 5.3 c/deg) with a 90% contrast were used as visual stimuli. The latencies and amplitudes of N70 and P100 of the transient VEPs were measured. The steady-state VEPs were Fourier analyzed, and both the phase and amplitude of the second (2F) and fourth (4F) harmonic responses were obtained. Binocular interaction was influenced by spatial frequency such that a binocular summation or even an inhibition occurred. For the transient VEPs, a binocular summation was more pronounced in the amplitude of N70 than in that of PI00 at all spatial frequencies. There were no significant effects of binocular stimulation on latencies of N70 or P100. However, the latencies of N70 and P100 showed different spatial frequency characteristics. For the steady-state VEPs, the amplitude of 2F revealed a binocular summation that was more pronounced at 5.3 c/deg, whereas the 4F amplitude showed binocular inhibition at 2.6 and 5.3 c/deg. The 2F phase showed binocular inhibition at all spatial frequencies, whereas no such inhibition was observed in the 4F phase. These results suggest that individual components of transient and steady-state VEPs are physiologically distinct and may therefore be generated from different neuronal populations in striate cortex.

Italian Journal of Neurological Sciences - ITAL J NEUROL SCI, 1997

Monocular and binocular visual evoked potentials (VEPs) in response to different check sizes (15-21-38-84 minutes of arc) were studied in 14 subjects with normal visual acuity and stereopsis.The binocular VEP amplitude is slightly higher than the VEP amplitude on stimulation of the better eye and significantly higher than the VEP amplitude on stimulation of the worse eye; this effect is observed using small checks and almost exclusively involves N75-P100.Both the N75 and P100 peaks occur earlier after binocular than monocular stimulation. The shortening of the N75 mean latency is significantly greater than that of the P100 mean latency when larger check sizes are used.The mean latency of the N145 potential is not significantly different in monocular and binocular stimulus conditions. The slight summation effect and latency shortening in the binocular VEPs are not consistent with the hypothesis that it is the sum of separate monocular signals originating from the visual cortex that g...

Graefe's Archive for Clinical and Experimental Ophthalmology, 1988

A correlate of binocular-neuron activity was found in some properties of visual evoked potentials (VEPs), such as facilitation (defined as a binocular response greater than the sum of the monocular responses) and changes in latency (shortening of binocular VEP latency as compared to that of monocular VEPs). Monocular and binocular steady-state VEPs in response to phase-alternating gratings of different contrast and both spatial and temporal frequency were recorded in three normal subjects. Fourier analysis of the responses was performed to isolate the component at the reversal frequency. Binocular VEPs showed facilitation in the low-contrast range (3%-10%). Facilitation was highest for gratings that had spatial frequency of 0.65 cycles/degree (c/d), alternating at 16 reversals per second. Phase shortening was found across a parameter range larger than that at which amplitude facilitation occurred. These results suggest that both amplitude facilitation and phase shortening in binocular VEPs may provide an objective measure of binocular visual function in clinical ophthalmology.

Purpose. Psychophysical studies have shown that a dark-adapted eye exerts a tonic interocular suppression (TIS) upon spatial vision mediated by the contralateral eye. The present study was designed to demonstrate TIS by means of visual evoked potential (VEP) procedures.

Documenta …, 1999

Abstract. In this study we sought to determine whether a natural condition involving fine discrimination, for example moderately severe myopia, might yield interesting information regarding the binocular interaction expressed by visual evoked potentials (VEPs). We studied ten ...

Graefe's Archive for Clinical and Experimental Ophthalmology, 1994

Background: Recent evidence indicates that an index of binocular activity may be found in some properties of steady-state visual evoked potentials (VEPs), such as amplitude facilitation and phase shortening. We evaluated binocular interactions with steady-state VEPs in normal subjects as well as in pashortening of binocular steadystate VEPs reflect abnormal binocular interactions associated with different forms of sensorial adaptation in concomitant strabismus.

Electroencephalography and clinical neurophysiology, 1981

The electrophysiology of normal binocular function was investigated by studying the binocular interactions from monocular and binocular visual evoked potentials (VEPs) recorded under a range of stimulus conditions. The amplitude and phase of the steady-state VEPs, which were obtained with sinusoidal gratings temporally modulated in counterphase, were measured with synchronous narrow-band filtering techniques. Binocular interactions were investigated as functions of spatial frequency, temporal frequency and contrast. Detailed sampling and testing within each stimulus domain revealed an unprecedented degree of VEP specificity in the extent of binocular interaction, which varied from zero summation to pronounced facilitation. Binocular facilitation was explored in terms of its relation to the neural mechanisms subserving binocular function. VEP correlates of rivalry, fusion and stereopsis were obtained. The facilitatory binocular interactions, revealed by careful spatial and temporal s...

Journal of Vision, 2005

Visual evoked potentials (VEPs) were recorded in response to a vernier onset/offset target presented to one eye that was combined with matching static targets in the other eye. The monocular response was dominated by a negative peak at 160 ms that occurred after a set of offsets was introduced into a one-dimensional random bar pattern. The static targets produced no discernible VEP response by themselves, but when fused binocularly with the oscillating vernier target, they produced shifts in perceived visual direction that influenced the VEP response. A vernier target fused with static vertical bars was perceived to alternate in depth between a flat surface and one broken into two interleaved surfaces. The response to this "surface-breaking" was as large or larger than the response to the monocular vernier offset. This response was much reduced when the oscillating vernier was fused with a static offset vernier (5' offset) that produced a percept of segregated regions moving in depth. Apparently, the VEP is strongly driven by shifts in visual direction that alter surface, texture, or contour contiguity.

Acta Ophthalmologica, 2009

T h e effect of mean luminosity change on pattern reversal visual evoked response (VER), especially monocular VER, binocular VER and binocular summation, was studied. T h e mean luminosity level was changed with the use of n e h a l density filters. When mean luminosity level was decreased binocularly, binocular and monocular VER amplitudes decreased and binocular summation increased, reaching its peak at a luminositv of -0.3 log foot-lambert. When mean luminosity was changed monocularly and the interocular luminosity difference was larger than 0.6 log unit, the binocular VER became almost equal to or smaller than the monocular VER. In dim luminosity, the binocular system functioned better than the monocular system. Even a slight luminosity difference between the two eyes could disturb the binocular system.

Annals of the New York Academy of Sciences, 1980