Journal article

Publication year: 2021

Journal: Journal of Vision

Volume number: 21

Issue number: 8

ISSN: 1534-7362

Open access status: Gold

DOI Link: https://doi.org/10.1167/jov.21.8.12

Publisher: Association for Research in Vision and Ophthalmology

Abstract: 
Color vision in humans starts with three types of cones (short [S], medium [M], and long [L] wavelengths) in the retina and three retinal and subcortical cardinal mechanisms, which linearly combine cone signals into the luminance channel (L + M), the red-green channel (L - M), and the yellow-blue channel (S-(L + M)). Chromaticmechanisms at the cortical level, however, are less well characterized. The present study investigated such higher-order chromatic mechanisms by recording electroencephalograms (EEGs) on human observers in a noise masking paradigm. Observers viewed colored stimuli that consisted of a target embedded in noise. Color directions of the target and noise varied independently and systematically in an isoluminant plane of color space. The target was flickering on-off at 3 Hz, eliciting steady-state visual evoked potential (SSVEP) responses. As a result, the masking strength could be estimated from the SSVEP amplitude in the presence of 6 Hz noise. Masking was strongest (i.e. target eliciting smallest SSVEPs) when the target and noise were along the same color direction, and was weakest (i.e. target eliciting highest SSVEPs) when the target and noise were along orthogonal directions. This pattern of results was observed both when the target color varied along the cardinal and intermediate directions, which is evidence for higher-order chromatic mechanisms tuned to intermediate axes. The SSVEP result can be well predicted by a model with multiple broadly tuned chromatic mechanisms. In contrast, a model with only cardinal mechanisms failed to account for the data. These results provide strong electrophysiological evidence for multiple chromatic mechanisms in the early visual cortex of humans.

Harvard Citation style: Chen, J. and Gegenfurtner, K. (2021) Electrophysiological evidence for higher-level chromatic mechanisms in humans, Journal of Vision, 21(8), Article 12. https://doi.org/10.1167/jov.21.8.12

APA Citation style: Chen, J., & Gegenfurtner, K. (2021). Electrophysiological evidence for higher-level chromatic mechanisms in humans. Journal of Vision. 21(8), Article 12. https://doi.org/10.1167/jov.21.8.12