Binocular interaction and steady-state visual evoked potentials (original) (raw)
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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...
Binocularity in the human visual evoked potential: facilitation, summation and suppression
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...
Monocular contribution to the peak time of the binocular pattern visual evoked potential
Documenta Ophthalmologica, 1995
The contribution of each monocular pathway to the timing of the binocular pattern visual evoked potential was assessed in situations where a significant interocular timing discrepancy was observed. Monocular and binocular pattern visual evoked potentials to 0.5 ° checks were recorded from normal subjects, normal subjects in whom one eye was blurred, patients with monocular amblyopia, and patients with resolved unilateral optic neuritis. Normal subjects showed facilitation, while suppression was evidenced in subjects with monocular blurring. In patients with amblyopia, the affected pathway had no effect on binocular pattern visual evoked potential latency, suggesting that the amblyopic eye was suppressed. In contrast, all patients with optic neuritis showed binocular averaging. Our results show that different forms of binocular interaction are evidenced in normal subjects, in amblyopia and in optic neuritis, and suggest that a comparative analysis of monocular and binocular pattern visual evoked potential peak times brings valuable information to the clinical evaluation that could be used to distinguish disease processes further.
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.
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.
The effect of binocular stimulation on each component of transient and steady-state VEPs
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.
Effect of different stimulus configurations on the visual evoked potential (VEP)
Documenta Ophthalmologica, 2012
The purpose of this study was to assess changes in the response profile of the pattern visual evoked potential (VEP) using three stimulus configurations simulating visual-field scotomas: central circular and central blank fields increasing incrementally in diameter from 1°to 15°, hemi-field, and quadrant patterns. Five visually normal adult subjects (ages 22-68 years) were tested binocularly at 1 m for each stimulus configuration on 5 separate days. A checkerboard test pattern (64 9 64 black-and-white checks, 85 % contrast, 64 cd/m 2 luminance, 20 s of stimulus duration, 2-Hz temporal frequency) was used. The group mean VEP amplitude increased in a linear manner with increase in the central circular diameter (y = 0.805x ? 2.00; r = 0.986) and decrease in central blank field diameter (y =-0.769x ? 16.22; r = 0.987). There was no significant change in latency in nearly all cases. The group mean coefficient of variability results indicated that the VEP amplitude was repeatable for the different stimulus configurations. The finding of VEP response linearity for the circular stimulus fields, and repeatability for all stimulus configurations, suggests that the clinician may be able to use the VEP technique with the suggested test patterns as a rapid and simple tool for objective assessment for several types of visual-field defects for a range of abnormal visual conditions and special populations.
Visual evoked responses in humans with abnormal visual experience
The Journal of Physiology, 1975
1. The visual evoked response to a grating target of varying spatial frequency was examined for normal subjects and for subjects with meridional amblyopia. This condition, reduced visual resolution for specific target orientations, is associated with, and thought to result from, marked ocular astigmatism. 2. For normal subjects, the general relation between spatial frequency and the evoked response is similar to psychophysical contrast sensitivity data. Evoked response amplitudes to oblique gratings are typically reduced and this is analogous to the lower acuity for oblique compared to horizontal and vertical detail. 3. In addition to the oblique effect, the magnitude of the evoked response for meridional amblyopes depends upon grating orientation over most of the spatial frequency range tested (0‐5‐16 cycles/deg). The lowest evoked amplitude is found when stimulus grating orientation matches that for which acuity is reduced. 4. The evoked potentials spatial frequency response funct...