title: Early human visual cortex encodes surface brightness induced by dynamic context.
abstract: Visual scene perception owes greatly to surface features such as color and brightness. Yet, early visual cortical areas predominantly encode surface boundaries rather than surface interiors. Whether human early visual cortex may nevertheless carry a small signal relevant for surface perception is a topic of debate. We induced brightness changes in a physically constant surface by temporally modulating the luminance of surrounding surfaces in seven human participants. We found that fMRI activity in the V2 representation of the constant surface was in antiphase to luminance changes of surrounding surfaces (i.e., activity was in-phase with perceived brightness changes). Moreover, the amplitude of the antiphase fMRI activity in V2 predicted the strength of illusory brightness perception. We interpret our findings as evidence for a surface-related signal in early visual cortex and discuss the neural mechanisms that may underlie that signal in concurrence with its possible interaction with the properties of the fMRI signal.
authors.affiliation: Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands. v.vandeven@maastrichtuniversity.nl
authors.forename: Vincent
authors.initials: V
authors.lastname: van de Ven
authors.forename: Bert
authors.initials: B
authors.lastname: Jans
authors.forename: Rainer
authors.initials: R
authors.lastname: Goebel
authors.forename: Peter
authors.initials: P
authors.lastname: De Weerd
mesh_terms: D000328:Adult; D001931:Brain Mapping; D015350:Contrast Sensitivity / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D010775:Photic Stimulation; D014793:Visual Cortex / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*