Elsevier

Vision Research

Volume 44, Issue 7, March 2004, Pages 669-683
Vision Research

BOLD fMRI and psychophysical measurements of contrast response to broadband images

https://doi.org/10.1016/j.visres.2003.10.022Get rights and content
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Abstract

We have measured the relationship between image contrast, perceived contrast, and BOLD fMRI activity in human early visual areas, for natural, whitened, pink noise, and white noise images. As root-mean-square contrast increases, BOLD response to natural images is stronger and saturates more rapidly than response to the whitened images. Perceived contrast and BOLD fMRI responses are higher for pink noise than for white noise patterns, by the same ratio as between natural and whitened images. Spatial phase structure has no measurable effect on perceived contrast or BOLD fMRI response. The fMRI and perceived contrast response results can be described by models of spatial frequency response in V1, that match the contrast sensitivity function at low contrasts, and have more uniform spatial frequency response at high contrasts.

Keywords

Functional brain imaging
Psychophysics
Spatial vision
Models and theory
Natural images

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