Twenty seven patients with migraine without aura were investigated. The age was between 12 and 54 years; 5 were men and 22 women. The diagnosis of migraine was made according to the classification proposed by the International Headache Society. The method of visual evoked potential was performed with pattern reversal (VEP-PR), with monocular stimulation. The stimulation was performed with patte...

Physiological studies of color processing have typically measured responses to spatially varying chromatic stimuli such as gratings, while psychophysical studies of color include color naming, color and light, as well as spatial and temporal chromatic sensitivities. This raises the question of whether we have one or several cortical color processing systems. Here we show from non-linear analysi...

Steady state visual evoked potentials (SSVEP) are assumed to be regulated by multiple brain areas, yet the underlying mechanisms are not well understood. In this study, we utilized multi-channel intracranial recordings together with network analysis to investigate the underlying relationships between SSVEP and brain networks in anesthetized rat. We examined the relationship between SSVEP amplit...

The stimulant effects of caffeine on cognitive performance have been widely investigated. The visual evoked potential, specially the P300 component, has been used in studies that explain the stimulant mechanisms of caffeine through neurophysiological methods. In this context, the present study aimed to investigate electrophysiological changes (P300 latency) and modification of cognitive and mot...

When geometric or contoured shapes are generated as disparity regions in dynamic random-dot stereograms, the question of whether the subject's response is evoked largely by boundaries and corners of the disparate region arises. To examine this question a disparate square was shifted randomly within a focal region at one millisecond intervals, resulting in a nebulous stimulus which "welled up" i...

The direction-reversal visual evoked potential (DR-VEP) latency is a key measure of the development of motion processing in infancy. However, the latency of this response has not been previously investigated. For other stimuli, both the latency of an initial peak and a latency measure calculated from steady-state phase as a function of frequency have been shown to be important and distinctive i...

Psychophysical and fMRI studies have indicated that visual processing of global symmetry has distinctive scaling properties, and proceeds more slowly than analysis of contrast, spatial frequency, and texture. We therefore undertook a visual evoked potential (VEP) study to directly compare the dynamics of symmetry and texture processing, and to determine the extent to which they interact. Stimul...

We used an electrophysiological measure of selective stimulus processing (the steady-state visual evoked potential, SSVEP) to investigate feature-specific attention to color cues. Subjects viewed a display consisting of spatially intermingled red and blue dots that continually shifted their positions at random. The red and blue dots flickered at different frequencies and thereby elicited distin...

Conscious and unconscious visuo-spatial processes are mainly related to parieto-occipital cortical activation. In this study, the working hypothesis was that a specific pattern of parieto-occipital activation is induced by conscious, as opposed to unconscious, visuo-spatial processes. Electroencephalographic data (128 channels) were recorded in 12 normal adults during a visuo-spatial task. A cu...

To investigate whether processing underlying texture segmentation is limited when texture is not attended, we measured orientation discrimination accuracy and visual evoked potentials (VEPs) while a texture bar was cyclically alternated with a uniform texture, either attended or not. Orientation discrimination was maximum when the bar was explicitly attended, above threshold when implicitly att...