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

Sae Kaneko,Ichiro Kuriki,Søren K Andersen

doi:10.1093/texcom/tgaa059

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.

Highlights

Any color we see starts with the excitation of 3 types of cones at the retina
We explored the hue selective responses in early cortical visual areas through recordings of steady-state visual evoked potentials (SSVEPs), elicited by a f lickering checkerboard whose color smoothly swept around the hue circle defined in a cone-opponent color space
These results indicate that hue representations in the early visual cortex, measured by the SSVEP technique, are possibly related to perceptual color contrast

Summary

Introduction

Any color we see starts with the excitation of 3 types of cones at the retina These cones have different peak sensitivity wavelength and we call them long-, medium-, and short-wavelength sensitive (in short, L-, M-, and S-) cones. The signals from these cones are transformed via neurons in the retina that form the color selectivity of ganglion cells. Color selective retinal ganglion cells receive opposed L- and M- cone signals or S cone signals opposed to the sum of L- and M-cone signals, and these signals are further carried into the lateral geniculate nucleus (LGN) (Derrington et al 1984; Hanazawa et al 2000). Selectivity to intermediate hues is achievable by the combination of coneopponent signals in the cortex (Hanazawa et al 2000; Wachtler et al 2003), whether such reconstructions of the signals are carried out in human V1 or other early visual areas is still an unsolved issue

Methods

Results

Conclusion