Measurements of long-range suppression in human opponent S-cone and achromatic luminance channels

TY - JOUR

T1 - Measurements of long-range suppression in human opponent S-cone and achromatic luminance channels

AU - Xiao, Bei

AU - Wade, Alex R

PY - 2010

Y1 - 2010

N2 - Cortical responses to spatially discrete patches of achromatic luminance contrast can be altered by the presence of high-contrast, spatially remote "surrounds" and this achromatic "surround suppression" has been the subject of much recent research. However, the nature of long-range contrast normalization in chromatic signals has been less studied. Here we use a combination of neuroimaging data from source-imaged EEG and two different psychophysical measures of surround suppression to study contrast normalization in stimuli containing achromatic luminance and S-cone-isolating contrast. In an appearance matching task, we find strong within-channel but little between-channel suppression. However, using a contrast increment detection task, we do find evidence for weak but significant between-channel effects. Our neural measurements agree with the appearance matching data, showing significant within-channel suppression and no significant interactions between signals initiated in different pre-cortical pathways. We hypothesize that appearance judgments and V1 population responses are dominated by neurons with chromatically matched classical and extra-classical surrounds while contrast increment detection tasks rely on a subpopulation of neurons that have extra-classical surrounds sensitive to both chromatic and achromatic contrasts. Our psychophysical and source-imaged EEG results are consistent with a hypothesis based on natural scene statistics that long-range contrast normalization in early visual system is largely driven by signals within the same chromatic channel.

AB - Cortical responses to spatially discrete patches of achromatic luminance contrast can be altered by the presence of high-contrast, spatially remote "surrounds" and this achromatic "surround suppression" has been the subject of much recent research. However, the nature of long-range contrast normalization in chromatic signals has been less studied. Here we use a combination of neuroimaging data from source-imaged EEG and two different psychophysical measures of surround suppression to study contrast normalization in stimuli containing achromatic luminance and S-cone-isolating contrast. In an appearance matching task, we find strong within-channel but little between-channel suppression. However, using a contrast increment detection task, we do find evidence for weak but significant between-channel effects. Our neural measurements agree with the appearance matching data, showing significant within-channel suppression and no significant interactions between signals initiated in different pre-cortical pathways. We hypothesize that appearance judgments and V1 population responses are dominated by neurons with chromatically matched classical and extra-classical surrounds while contrast increment detection tasks rely on a subpopulation of neurons that have extra-classical surrounds sensitive to both chromatic and achromatic contrasts. Our psychophysical and source-imaged EEG results are consistent with a hypothesis based on natural scene statistics that long-range contrast normalization in early visual system is largely driven by signals within the same chromatic channel.

KW - Adult

KW - Color Perception

KW - Color Vision

KW - Contrast Sensitivity

KW - Discrimination (Psychology)

KW - Electroencephalography

KW - Evoked Potentials, Visual

KW - Female

KW - Humans

KW - Lighting

KW - Male

KW - Neural Inhibition

KW - Photic Stimulation

KW - Psychophysics

KW - Retinal Cone Photoreceptor Cells

KW - Visual Fields

KW - Visual Pathways

UR - http://www.scopus.com/inward/record.url?scp=78449249327&partnerID=8YFLogxK

U2 - 10.1167/10.13.10

DO - 10.1167/10.13.10

M3 - Article

C2 - 21149312

VL - 10

SP - 1

EP - 19

JO - Journal of Vision

JF - Journal of Vision

IS - 13

M1 - 10

ER -