purpose: to evaluate the effect of vertical prism induced stress on binocular visual evoked potentials. methods: using checkerboard stimulus patterns in two spatial frequencies (sfs) of 0.48 cpd as a low sf and 2.18 cpd as a moderate sf reversing with temporal frequency of 4 hz, the effect of increasing visual stress using vertical prisms of 0, 1, 2 and 3 prism diopters on binocular visual evok...

This study investigated the effect of attention on the contrast response curves of steady-state visual evoked potentials (VEPs) to counter-phased sinusoidal gratings. The 1 cyc/deg gratings were modulated either in luminance or chromaticity (equiluminant red-green). The luminance grating counter-phased at 9 Hz (to favour activation of the magno-cellular system), and the chromatic grating at 2.5...

To determine the manner in which attention is distributed among numerous locations in the visual space, we used a multifocal recording technique that allowed simultaneous recordings of evoked cortical activity from 12 visual field areas out to 23.6 degrees. We found that multifocal visual evoked potential (mfVEP) amplitude was larger when a region of visual space was attended than when it was n...

Dynamic random dot fusion, stereopsis and stereoacuity were evaluated in 149 healthy, fullterm infants, using both forced-choice preferential looking (FPL) and steady-state visual evoked potential (VEP) protocols. Few infants aged 2-3 months demonstrated fusion or stereopsis in either the FPL or VEP protocol; most infants aged 5 months and older demonstrated fusion and stereopsis in both protoc...

In this paper, an extended multifocal VEP/ERG paradigm, referred to as the unified multifocal electroretinography and visual evoked potential paradigm (UMEV), is presented. This paradigm allows a simultaneous recording of luminance responses, temporal interactions, spatial interactions and spatial-temporal interactions. Two studies were conducted to demonstrate the capability and validity of th...

The present paper complements our investigations on children's and adult's EEGs and evoked potentials elicited by mean of auditory stimulation. We analyzed the spectral characteristics of spontaneously recorded EEGs, visual evoked potentials, and frequency responses of a group of 3-year-old children. The results were compared to the corresponding measurements in adults aged 20-22 years. Our fin...

Chromatic contrast thresholds may be estimated from transient VEPs by measuring the peak-to-peak amplitude at a range of stimulus levels followed by extrapolation to zero amplitude. However, there have been reports of failure of this technique when applied to the transient chromatic VEP due to variability of amplitude, difficulties with component identification and poor correlation of amplitude...

This study deals with the effect of stimulus contrast, between 1.3% and 96%, on the visual evoked potentials (VEPs) for onset of motion and for pattern reversal of checkerboard stimuli. The VEPs for pattern reversal and for the onset of motion both contain an initial positive peak (P1; peak latency about 120 msec) followed by a later negative peak (N2; peak latency 160-200 msec). However the P1...

The intersubject and intrasubject reproducibility of the VEP was evaluated using two different methods of producing pattern reversal--a mirror/projector system and a light-emitting diode (LED) system. Intersubject reproducibility was determined in 100 normal subjects (50 males, 50 females). Ten subjects were studied on ten different occasions over 11 months to establish intrasubject reproducibi...

Pattern reversal visual evoked potentials (VEPs) have been elicited in 16 female hyperthyroid patients before and after treatment and compared with those from a similar group of age and sex matched control subjects. No effect on latency was seen, and although larger amplitude values were noted in the thyrotoxic group these too were not significant. We would conclude that hyperthyroidism per se ...