Increasing spatial frequency of S-cone defined gratings reduces their visibility and brain response more than for gratings defined by L-M cone contrast

TY - JOUR

T1 - Increasing spatial frequency of S-cone defined gratings reduces their visibility and brain response more than for gratings defined by L-M cone contrast

AU - Lowndes, Rebecca

AU - Welbourne, Lauren

AU - Williams, Molly

AU - Gouws, Andre

AU - Wade, Alex

AU - Morland, Antony

N1 - © 2023 The Author(s).

PY - 2023/6/1

Y1 - 2023/6/1

N2 - Chromatic sensitivity reduces as spatial frequency increases. Here, we explore the behavioural and neuronal responses to chromatic stimuli at two spatial frequencies for which the difference in sensitivity will be greater for S-cone than L-M stimuli. Luminance artefacts were removed using the Random Luminance Modulation (RLM) technique. As expected, doubling the spatial frequency increased the detection threshold more for S-cone than for isoluminant L-M gratings. We then used fMRI to measure the cortical BOLD responses to the same two chromatic stimuli (S and L-M) at the same two spatial frequencies. Responses were measured in six visual areas (V1, V2, V3, V3a, hV4, TO1/2). We found a significant interaction between spatial frequency in V1, V2 and V4 suggesting that the behaviourally observed increase in contrast threshold for high spatial frequency S-cone stimuli is reflected in these retinotopic areas. Our measurements show that neural responses consistent with psychophysical behaviour in a colour detection task can be observed as early as primary visual cortex.

AB - Chromatic sensitivity reduces as spatial frequency increases. Here, we explore the behavioural and neuronal responses to chromatic stimuli at two spatial frequencies for which the difference in sensitivity will be greater for S-cone than L-M stimuli. Luminance artefacts were removed using the Random Luminance Modulation (RLM) technique. As expected, doubling the spatial frequency increased the detection threshold more for S-cone than for isoluminant L-M gratings. We then used fMRI to measure the cortical BOLD responses to the same two chromatic stimuli (S and L-M) at the same two spatial frequencies. Responses were measured in six visual areas (V1, V2, V3, V3a, hV4, TO1/2). We found a significant interaction between spatial frequency in V1, V2 and V4 suggesting that the behaviourally observed increase in contrast threshold for high spatial frequency S-cone stimuli is reflected in these retinotopic areas. Our measurements show that neural responses consistent with psychophysical behaviour in a colour detection task can be observed as early as primary visual cortex.

U2 - 10.1016/j.visres.2023.108209

DO - 10.1016/j.visres.2023.108209

M3 - Article

C2 - 36871329

SN - 0042-6989

VL - 207

JO - Vision Research

JF - Vision Research

M1 - 108209

ER -