Limits...
Fovea-periphery axis symmetry of surround modulation in the human visual system.

Nurminen L, Kilpeläinen M, Vanni S - PLoS ONE (2013)

Bottom Line: We measured surround modulation of blood-oxygenation-level-dependent signal and perceived contrast with surrounds that extended either towards the periphery or the fovea from a center stimulus, centered at 6° eccentricity.This design compares the effects of two surrounds which are identical in visual field size, but differ in the sizes of their cortical representations.Although the fovea-periphery anisotropy affects nearly all aspects of spatial vision, our results suggest that in surround modulation the visual system compensates for it.

View Article: PubMed Central - PubMed

Affiliation: Brain Research Unit, O.V. Lounasmaa Laboratory, Aalto University, Espoo, Finland. lnurmin@neuro.hut.fi

ABSTRACT
A visual stimulus activates different sized cortical area depending on eccentricity of the stimulus. Here, our aim is to understand whether the visual field size of a stimulus or cortical size of the corresponding representation determines how strongly it interacts with other stimuli. We measured surround modulation of blood-oxygenation-level-dependent signal and perceived contrast with surrounds that extended either towards the periphery or the fovea from a center stimulus, centered at 6° eccentricity. This design compares the effects of two surrounds which are identical in visual field size, but differ in the sizes of their cortical representations. The surrounds produced equally strong suppression, which suggests that visual field size of the surround determines suppression strength. A modeled population of neuronal responses, in which all the parameters were experimentally fixed, captured the pattern of results both in psychophysics and functional magnetic resonance imaging. Although the fovea-periphery anisotropy affects nearly all aspects of spatial vision, our results suggest that in surround modulation the visual system compensates for it.

Show MeSH

Related in: MedlinePlus

Surround suppression of perceived contrast as a function of the gap size.The different panels present data of different subjects. Connected data points mark the measured mean ± s.e.m. Smooth curves present the modeled suppression. Model parameters were fixed based on the area summation experiment for each subject separately. Red marks the inward surround condition and black the outward.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3585267&req=5

pone-0057906-g003: Surround suppression of perceived contrast as a function of the gap size.The different panels present data of different subjects. Connected data points mark the measured mean ± s.e.m. Smooth curves present the modeled suppression. Model parameters were fixed based on the area summation experiment for each subject separately. Red marks the inward surround condition and black the outward.

Mentions: The main finding of this experiment was that the inward and the outward surrounds produced highly similar effects on perceived contrast of the center (Figure 3). Suppression was strong with small gap sizes and increasing the gap size decreased suppression strength. As the gap size was increased from 0.1 to 2.1°, the mean suppression strength decreased from 24.5±4.2% to 4.7±1.5% (paired two-tailed t-test, t(4) = 3.74, p<0.05) in the inward surround condition. For the outward surround, the corresponding decrease was from 18.7±4.2% to 3.5±2.1% (t(4) = 3.62, p<0.05). In all of the subjects and gap sizes, difference between the inward and the outward surrounds was statistically insignificant (paired two-tailed t-tests, family-wise error corrected, p>0.05).


Fovea-periphery axis symmetry of surround modulation in the human visual system.

Nurminen L, Kilpeläinen M, Vanni S - PLoS ONE (2013)

Surround suppression of perceived contrast as a function of the gap size.The different panels present data of different subjects. Connected data points mark the measured mean ± s.e.m. Smooth curves present the modeled suppression. Model parameters were fixed based on the area summation experiment for each subject separately. Red marks the inward surround condition and black the outward.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585267&req=5

pone-0057906-g003: Surround suppression of perceived contrast as a function of the gap size.The different panels present data of different subjects. Connected data points mark the measured mean ± s.e.m. Smooth curves present the modeled suppression. Model parameters were fixed based on the area summation experiment for each subject separately. Red marks the inward surround condition and black the outward.
Mentions: The main finding of this experiment was that the inward and the outward surrounds produced highly similar effects on perceived contrast of the center (Figure 3). Suppression was strong with small gap sizes and increasing the gap size decreased suppression strength. As the gap size was increased from 0.1 to 2.1°, the mean suppression strength decreased from 24.5±4.2% to 4.7±1.5% (paired two-tailed t-test, t(4) = 3.74, p<0.05) in the inward surround condition. For the outward surround, the corresponding decrease was from 18.7±4.2% to 3.5±2.1% (t(4) = 3.62, p<0.05). In all of the subjects and gap sizes, difference between the inward and the outward surrounds was statistically insignificant (paired two-tailed t-tests, family-wise error corrected, p>0.05).

Bottom Line: We measured surround modulation of blood-oxygenation-level-dependent signal and perceived contrast with surrounds that extended either towards the periphery or the fovea from a center stimulus, centered at 6° eccentricity.This design compares the effects of two surrounds which are identical in visual field size, but differ in the sizes of their cortical representations.Although the fovea-periphery anisotropy affects nearly all aspects of spatial vision, our results suggest that in surround modulation the visual system compensates for it.

View Article: PubMed Central - PubMed

Affiliation: Brain Research Unit, O.V. Lounasmaa Laboratory, Aalto University, Espoo, Finland. lnurmin@neuro.hut.fi

ABSTRACT
A visual stimulus activates different sized cortical area depending on eccentricity of the stimulus. Here, our aim is to understand whether the visual field size of a stimulus or cortical size of the corresponding representation determines how strongly it interacts with other stimuli. We measured surround modulation of blood-oxygenation-level-dependent signal and perceived contrast with surrounds that extended either towards the periphery or the fovea from a center stimulus, centered at 6° eccentricity. This design compares the effects of two surrounds which are identical in visual field size, but differ in the sizes of their cortical representations. The surrounds produced equally strong suppression, which suggests that visual field size of the surround determines suppression strength. A modeled population of neuronal responses, in which all the parameters were experimentally fixed, captured the pattern of results both in psychophysics and functional magnetic resonance imaging. Although the fovea-periphery anisotropy affects nearly all aspects of spatial vision, our results suggest that in surround modulation the visual system compensates for it.

Show MeSH
Related in: MedlinePlus