scholarly journals Steady-State Visual Evoked Potentials Elicited from Early Visual Cortex Reflect Both Perceptual Color Space and Cone-Opponent Mechanisms

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Sae Kaneko ◽  
Ichiro Kuriki ◽  
Søren K Andersen
Keyword(s):  
Visual Cortex ◽  
Steady State ◽  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Color Space ◽  
Color Contrast ◽  
Response Latencies ◽  
Opponent Color ◽  
Early Visual Cortex ◽  
Visual Evoked

Abstract Colors are represented in the cone-opponent signals, L-M versus S cones, at least up to the level of inputs to the primary visual cortex. We explored the hue selective responses in early cortical visual areas through recordings of steady-state visual evoked potentials (SSVEPs), elicited by a flickering checkerboard whose color smoothly swept around the hue circle defined in a cone-opponent color space. If cone opponency dominates hue representation in the source of SSVEP signals, SSVEP amplitudes as a function of hue should form a profile that is line-symmetric along the cardinal axes of the cone-opponent color space. Observed SSVEP responses were clearly chromatic ones with increased SSVEP amplitudes and reduced response latencies for higher contrast conditions. The overall elliptic amplitude profile was significantly tilted away from the cardinal axes to have the highest amplitudes in the “lime-magenta” direction, indicating that the hue representation in question is not dominated by cone-opponency. The observed SSVEP amplitude hue profile was better described as a summation of a perceptual response and cone-opponent responses with a larger weight to the former. These results indicate that hue representations in the early visual cortex, measured by the SSVEP technique, are possibly related to perceptual color contrast.

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

2008 ◽  
Vol 25 (3) ◽  
pp. 333-339 ◽  
Author(s):  
BRUNO D. GOMES ◽  
GIVAGO S. SOUZA ◽  
MONICA G. LIMA ◽  
ANDERSON R. RODRIGUES ◽  
CÉZAR A. SAITO ◽  
...  
Keyword(s):  
Steady State ◽  
Evoked Potentials ◽  
Fundamental Frequency ◽  
Visual Evoked Potentials ◽  
Second Harmonic ◽  
Color Space ◽  
Color Discrimination ◽  
Pattern Reversal ◽  
Different Color ◽  
Visual Evoked

The purpose of this work is to investigate the use of different forms of visual evoked potentials (VEPs) to measure color discrimination thresholds and to plot color discrimination ellipses (MacAdam, 1942). Five normal trichromats (24.5 ± 2.6 years-old) were monocularly tested. Stimuli consisted of sinusoidal isoluminant chromatic gratings made from chromaticity pairs located along four different color directions radiating from one reference point of the CIE 1976 chromaticity diagram (u′ = 0.225; v′ = 0.415). Heterochromatic flicker photometry (HFP) was used to obtain the isoluminance condition for every subject and for all chromaticity pairs. VEPs were elicited using two cycles per degree grating stimuli at three different temporal configurations: transient, onset (300 ms)/offset (700 ms), 1 Hz fundamental frequency; steady-state, onset (50 ms)/offset (50 ms), 10 Hz fundamental frequency; and steady-state pattern reversal at 5 Hz fundamental frequency (10 Hz phase reversal). VEP amplitude was measured using transient VEP N1-P1 components and steady state VEP first (10 Hz) and second (20 Hz) harmonics. VEP amplitude was plotted as a function of chromatic distance in the CIE 1976 color space and the data points were extrapolated to zero amplitude level to obtain chromatic discrimination thresholds. The results were compared with psychophysical measurements performed using the same stimulus configurations and with the pseudoisochromatic method of Mollon-Reffin (one-way ANOVA). For all subjects and all stimulation methods, the ellipses showed small sizes, low ellipticities, and were vertically oriented. Despite some consistent differences in the results obtained with different procedures, there was no statistical difference between ellipses obtained electrophysiologically and psychophysically. For steady state VEPs, ellipses obtained from second harmonic amplitudes were larger and more elongated in the tritan direction than those obtained with first harmonic amplitudes.

scholarly journals Cortical Double-Opponent Cells in Color Perception: Perceptual Scaling and Chromatic Visual Evoked Potentials

i-Perception ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 204166951775271 ◽  
Author(s):  
Valerie Nunez ◽  
Robert M. Shapley ◽  
James Gordon
Keyword(s):  
Visual Cortex ◽  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Visual Evoked Potential ◽  
Evoked Potential ◽  
Color Perception ◽  
Neural Substrates ◽  
Response Dynamics ◽  
Early Visual Cortex ◽  
Visual Evoked

In the early visual cortex V1, there are currently only two known neural substrates for color perception: single-opponent and double-opponent cells. Our aim was to explore the relative contributions of these neurons to color perception. We measured the perceptual scaling of color saturation for equiluminant color checkerboard patterns (designed to stimulate double-opponent neurons preferentially) and uniformly colored squares (designed to stimulate only single-opponent neurons) at several cone contrasts. The spatially integrative responses of single-opponent neurons would produce the same response magnitude for checkerboards as for uniform squares of the same space-averaged cone contrast. However, perceived saturation of color checkerboards was higher than for the corresponding squares. The perceptual results therefore imply that double-opponent cells are involved in color perception of patterns. We also measured the chromatic visual evoked potential (cVEP) produced by the same stimuli; checkerboard cVEPs were much larger than those for corresponding squares, implying that double-opponent cells also contribute to the cVEP response. The total Fourier power of the cVEP grew sublinearly with cone contrast. However, the 6-Hz Fourier component’s power grew linearly with contrast-like saturation perception. This may also indicate that cortical coding of color depends on response dynamics.

P239 The influence of mental activity to steady-state visual evoked potentials (SSVEP)

1996 ◽  
Vol 99 (4) ◽  
pp. 327
Author(s):  
V. Radivojević ◽  
M. Car ◽  
M. Rajković ◽  
. Martinović ◽  
N. Krstić
Keyword(s):  
Steady State ◽  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Mental Activity ◽  
Visual Evoked
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