Cortical magnification eliminates differences in contrast sensitivity across but not around the visual field

Jigo, Michael; Tavdy, Daniel; Himmelberg, Marc M.; Carrasco, Marisa

doi:10.7554/elife.84205

Cited by 20 publications

(24 citation statements)

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“…Our study reveals that the benefit of presaccadic attention on the CSF changes as a function of polar angle. During fixation, there were robust horizontal-vertical and vertical meridian asymmetries (HVA and VMA) effects in peak-CS, cutoff-SF, and AULCSF, but not in peak-SF, consistent with previous studies (Barbot, Xue, & Carrasco, 2021;Jigo et al, 2023). "N/$*,="&'((')%"4$%4'$'+*-,@"+0%"%I+%,+"->"+0%"'&522%+$*%&">-$"&-2%"->"+0%"…”

Section: Discussionsupporting

confidence: 90%

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Presaccadic attention enhances and reshapes the Contrast Sensitivity Function differentially around the visual field

Kwak,

Zhao,

et al. 2023

Preprint

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The visual world is processed with a great degree of non-uniformity across eccentricity and around polar angle locations. Contrast sensitivity, a fundamental visual dimension constraining our vision, drops drastically from foveal to peripheral locations. It also decreases from the horizontal to the vertical meridian, and from the lower vertical to the upper vertical meridian (i.e., polar angle asymmetries). Moreover, contrast sensitivity is a function of spatial frequency, and the general relation between the two dimensions is referred to as the Contrast Sensitivity Function (CSF). To overcome constraints of the visual system throughout the visual field, we constantly make rapid saccadic eye movements to foveate on relevant objects in the visual scene. Already before saccade onset, attention shifts to the saccade target location (upcoming fovea) and enhances visual processing at that location. Thispresaccadic shift of attentiontypically benefits contrast sensitivity, but it is unknown whether and how it modulates the CSF and if this effect varies around polar angle locations. Contrast sensitivity enhancement may result from a horizontal or vertical shift of the CSF, increase in bandwidth, or any of their combinations, and the magnitude may differ around the visual field. In the current study, we investigated these possibilities by extracting key attributes of the CSF using Hierarchical Bayesian Modeling. First, we characterized how the CSF varies around polar angle. Then we compared the CSF attributes during fixation and saccade preparation (presaccadic attention). The results reveal that presaccadic attention (1) enhances contrast sensitivity across a wide range of spatial frequencies, (2) increases both the most preferred and the highest discernable spatial frequency, and (3) narrows the bandwidth. Importantly, the presaccadic enhancement in contrast sensitivity was more pronounced along the horizontal than the vertical meridian, exacerbating the polar angle asymmetries present during fixation. In conclusion, presaccadic attention bridges the gap between presaccadic peripheral and post-saccadic foveal input by rendering more of the world visible at the saccade target, and more so at the horizontal than the vertical meridian.

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Section: Discussionsupporting

confidence: 90%

“…We found polar angle asymmetries in peak-CS, cutoff-SF, and AULCSF during fixation (Jigo et al, 2023).…”

Section: Introductionmentioning

confidence: 64%

Presaccadic attention enhances and reshapes the Contrast Sensitivity Function differentially around the visual field

Kwak,

Zhao,

et al. 2023

Preprint

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“…The finding that lower SFs are represented as more influential with increasing eccentricity is consistent with the fact that V1 simple cells prefer lower SF as eccentricity increases in macaques (De Valois et al, 1982b;Schiller et al, 1976a) and cats (Movshon et al, 1978a), (2) more cortex is devoted to higher SFs in the fovea than parafovea (Xu et al, 2007), and (3) the contrast sensitivity function in humans peaks at a higher SF at the fovea than perifovea (Hilz and Cavonius, 1974;Robson and Graham, 1981;Wright and Johnston, 1983;Jigo et al, 2023). Preference for higher SF at the fovea can be explained by the fact that V1 simple cells at the fovea have smaller RF (Hubel and Wiesel, 1962), which yields a preference for higher SF (Movshon et al, 1978a(Movshon et al, , 1978b.…”

Section: Featural Representations Differ Between Fovea and Perifoveasupporting

confidence: 80%

“…Visual performance worsens with eccentricity for many visual dimensions, including contrast sensitivity (Cannon, 1985;Baldwin et al, 2012;Jigo et al, 2023) and acuity (Strasburger et al, 2011;Anton-Erxleben and Carrasco, 2013). The behavioral advantage at the fovea relates to higher cone density (Polyak, 1941), smaller retinal receptive fields (Enroth-Cugell and Robson, 1966), and larger V1 area dedicated to processing stimuli (Virsu and Rovamo, 1979;Duncan and Boynton, 2003;Benson et al, 2021;Himmelberg et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Featural representation and internal noise underlie the eccentricity effect in contrast sensitivity

Xue

Fernández

Carrasco

2023

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Visual performance for basic visual dimensions (e.g., contrast sensitivity and acuity) peaks at the fovea and decreases with eccentricity. The eccentricity effect is related to larger surface area of the visual cortex corresponding to the fovea, but it is unknown if feature tuning differs across eccentricity and contributes to this eccentricity effect. Here, we investigated two system-level computations underlying the eccentricity effect: featural representation (tuning) and internal noise. Observers detected a Gabor embedded in filtered white noise which appeared at the fovea or one of four perifoveal locations. We used psychophysical reverse correlation to estimate the weights assigned by the visual system to a range of orientations and spatial frequencies in noisy stimuli, conventionally interpreted as perceptual sensitivity to the corresponding features. We found higher sensitivity to task-relevant orientations and SFs at the fovea than perifovea, and no difference in selectivity for either orientation or spatial frequency. Meanwhile, we measured response consistency using a double-pass method, which allowed us to infer the level of internal noise by implementing a noisy observer model. We found lower internal noise at the fovea than perifovea. Finally, individual variability in contrast sensitivity correlated with sensitivity to and selectivity for task-relevant features and with internal noise. Moreover, the behavioral eccentricity effect mainly reflects the foveal advantage in orientation sensitivity compared to other computations. These findings suggest that the eccentricity effect stems from a better representation of task-relevant features and lower internal noise at the fovea than at the perifovea.

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“…Instead, it improved CS similarly to training with high-contrast stimuli (Das et al, 2014; Huxlin et al, 2009; Saionz et al, 2020). Given that CS may be strongly related to the activity (Niemeyer & Paradiso, 2017) and number of V1 neurons (Himmelberg et al, 2022; Jigo et al, 2023) representing particular visual field regions, our findings suggest a potentially fundamental limitation of the V1-damaged visual system: with insufficient V1 neurons, the residual circuity may simply be incapable of the processing necessary to restore normal CS over affected parts of the visual field. Thus, in CB participants, the amount of spared V1 representing portions of the blind field (Barbot et al, 2021; Papanikolaou et al, 2014) along with maintenance of its retinal and subcortical input, may be vital to maximize recovery of CS.…”

Section: Discussionmentioning

confidence: 85%

Contrast sensitivity: a fundamental limit to vision restoration after V1 damage

Yang,

Saionz,

Cavanaugh

et al. 2023

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Stroke damage to the primary visual cortex (V1) causes severe visual deficits, which benefit from perceptual retraining. However, whereas training with high-contrast stimuli can locally restore orientation and direction discrimination abilities at trained locations, it only partially restores luminance contrast sensitivity (CS). Recent work revealed that high-contrast discrimination abilities may be preserved in the blind field of some patients early after stroke. Here, we asked if CS for orientation and direction discrimination is similarly preserved inside the blind field, to what extent, and whether it could benefit from a visual training intervention. Thirteen subacute (<3 months post-V1-stroke) and 12 chronic (>6 months post-V1-stroke) participants were pre-tested, then trained to discriminate either orientation or motion direction of Gabor patches of progressively lower contrasts. At baseline, more subacute than chronic participants could correctly discriminate the orientation of high-contrast Gabors in their blind field, but all failed to perform this task at lower contrasts, even when 10Hz flicker or motion direction were added. Training improved CS in a greater portion of subacute than chronic participants, but no-one attained normal CS, even when stimuli contained flicker or motion. We conclude that, unlike the near-complete training-induced restoration of high-contrast orientation and direction discrimination, there is limited capacity for restoring CS after V1 damage in adulthood. Our results suggest that CS involves different neural substrates and computations than those required for orientation and direction discrimination in V1-damaged visual systems.Significance statementStroke-induced V1 damage in adult humans induces a rapid and severe impairment of contrast sensitivity for orientation and direction discrimination in the affected hemifield, although discrimination of high-contrast stimuli can persist for months. Adaptive training with Gabor patches of progressively lower contrasts improves contrast sensitivity for these discriminations in the blind-field of both subacute (<3 months post-stroke) and chronic (>6 months post-stroke) participants, although it fails to restore fully-normal contrast sensitivity. Nonetheless, more subacute than chronic stroke participants benefit from such training, particularly when discriminating the orientation of static, non-flickering targets. Thus, contrast sensitivity appears critically dependent on processing within V1, with perceptual training displaying limited potential to fully restore it after V1 damage.

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Cortical magnification eliminates differences in contrast sensitivity across but not around the visual field

Cited by 20 publications

References 100 publications

Presaccadic attention enhances and reshapes the Contrast Sensitivity Function differentially around the visual field

Presaccadic attention enhances and reshapes the Contrast Sensitivity Function differentially around the visual field

Featural representation and internal noise underlie the eccentricity effect in contrast sensitivity

Contrast sensitivity: a fundamental limit to vision restoration after V1 damage

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