Color discrimination along the cardinal chromatic axes with VECPs as an index of function of the parvocellular pathway. Correspondence of intersubject and axis variations to psychophysics

Color discrimination ellipses of trichromats measured with transient and steady state visual evoked potentials

“…VEP recordings result from the activity of large cell groups in the primary visual cortex (V1), thus providing a direct physiological response that can be analyzed to give valuable information about basic properties of visual pathways involved in achromatic and chromatic vision (Murray et al, 1987; McKeefry et al, 1996; Souza et al, 2007). It is also an important tool to study congenital and acquired color vision deficiency, development, maturation, and aging of the color visual pathways (Crognale et al, 1993, 1998; Gomes et al, 2006) and to study chromatic visual performance, providing complementary information to that obtained with psychophysics (Regan, 1973; Macaluso et al, 1994, 1996; Rabin et al, 1994; Tobimatsu et al, 1995; Kulikowski et al, 1996; Porciatti & Sartucci, 1996, 1999; Suttle & Harding, 1999). One important VEP feature is that some of its components are related to selective properties of different visual pathways such as the magnocellular (M) and parvocellular (P) pathways (McKeefry et al, 1996; Baseler & Sutter, 1997; Souza et al, 2007).…”

A new color vep procedure discloses asymptomatic visual impairments in optic neuritis and glaucoma suspects

“…Disorders affecting the visual system may alter the function of only some of these parallel channels, leaving others relatively intact. This could be due to some technical drawbacks (14). The commonest visual stimulus used in routine investigations consists of high-contrast pattern reversal black/white checkerboards displayed at differing spatial frequencies.…”

“…Some investigators proposed pure chromatic contrast stimuli consisting of isoluminant red/green sinusoidal gratings as a speci®c way of stimulating the parvocellular system, but studies using these methods yielded controversial results. This could be due to some technical drawbacks (14). In fact,``pure'' chromatic contrast usually elicits small cortical responses that can be dif®cult to detect.…”

The Demands of Geometry on Color Vision

“…Equally perplexing is why we perceive a color gamut based on four color classes-reds, greens, blues and yellows-each defined by a unique hue that has no apparent admixture of the other three color classes [6][7][8][9]. And while it has long been known that color vision is mediated by the spectral sensitivities of short, medium, and long-wavelength cones whose output is processed by red-green and blue yellow opponent neurons [7,8,[10][11][12], why these particular properties have evolved in humans is also incompletely understood [7,11,13]. .…”