Aging of visual pathways was measured psychophysically and physiologically in subjects aged 20-89 years. Contrast thresholds for the chromatic pathways increased with age, but there were no significant changes for thresholds of the achromatic pathway at low spatial frequencies. For visual evoked potential (VEP) responses, again only the chromatic pathways were significantly affected by age. Age...

The flash visual evoked potential (F-VEP), elicited by a 100 ms diffuse light flash presented at 2 Hz, was examined in the cat primary visual cortex (Area 17). Intracortical F-VEP depth profiles were recorded to characterize waveform changes with electrode depth. A positive surface component, with a latency of 200 ms, was the dominant waveform feature within the cortex, reversing in polarity an...

Stimulus visibility can be reduced by other stimuli that overlap the same region of visual space, a process known as masking. Here we studied the neural mechanisms of masking in humans using source-imaged steady state visual evoked potentials and frequency-domain analysis over a wide range of relative stimulus strengths of test and mask stimuli. Test and mask stimuli were tagged with distinct t...

The purpose of this study was to investigate the relationship between kinetic visual acuity and reaction time in college students. Eighteen male college students, mean age: 21.5±2.2 years, participated in this study. Static and kinetic visual acuity and simple and choice reaction time were measured. In addition, visual evoked potential using pattern reversal stimulus was recorded. These items w...

Introduction: The most important aspect of a pediatric eye exam is the quantitative measurement of visual acuity, yet many children in a pediatric practice are nonverbal or preverbal. Methods: The clinician has a number of options for assessing vision in these children, including the central, steady, maintained technique, behavioral measurements, and electrophysiological measurements. Each of t...

Certain local features induce preattentive texture segregation. Recently, components in the visual evoked potential (VEP) associated with preattentive texture segregation (tsVEPs) have been demonstrated. To assess the similarity and dissimilarity of visual processing across visual dimensions, we compared VEPs and tsVEPs in texture segregation by luminance, orientation, motion and stereo dispari...