title: Activity in high-level brain regions reflects visibility of low-level stimuli.
abstract: Stimulus visibility is associated with neural signals in multiple brain regions, ranging from visual cortex to prefrontal regions. Here we used functional magnetic resonance imaging (fMRI) to investigate to which extent the perceived visibility of a "low-level" grating stimulus is reflected in the brain activity in high-level brain regions. Oriented grating stimuli were presented under varying visibility conditions created by backward masking. Visibility was manipulated using four different stimulus onset asynchronies (SOAs), which created a continuum from invisible to highly visible target stimuli. Brain activity in early visual areas, high-level visual brain regions (fusiform gyrus), as well as parietal and prefrontal brain regions was significantly correlated with subjects' psychometric visibility functions. In addition, increased stimulus visibility was reflected in the functional coupling between low and high-level visual areas. Specifically, neuroimaging signals in the middle occipital gyrus were significantly more correlated with signals in the inferior temporal gyrus when subjects successfully perceived the target stimulus than when they did not. These results provide evidence that not only low-level visual but also high-level brain regions reflect visibility of low-level grating stimuli and that changes in functional connectivity reflect perceived stimulus visibility.
authors.affiliation: Bernstein Center for Computational Neuroscience, Charité-Universitätsmedizin, Berlin, Germany; Berlin Center for Advanced Neuroimaging, Charité-Universitätsmedizin, Berlin, Germany; Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA. Electronic address: fatma.imamoglu@bccn-berlin.de.
authors.forename: F
authors.initials: F
authors.lastname: Imamoglu
authors.affiliation: Bernstein Center for Computational Neuroscience, Charité-Universitätsmedizin, Berlin, Germany; Berlin Center for Advanced Neuroimaging, Charité-Universitätsmedizin, Berlin, Germany; Translational Neuromodeling Unit (TNU), Inst. for Biomed. Engin., Univ. of Zurich & ETH Zurich, Zurich, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Heinzle
authors.affiliation: Bernstein Center for Computational Neuroscience, Charité-Universitätsmedizin, Berlin, Germany; Berlin Center for Advanced Neuroimaging, Charité-Universitätsmedizin, Berlin, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Imfeld
authors.affiliation: Bernstein Center for Computational Neuroscience, Charité-Universitätsmedizin, Berlin, Germany; Berlin Center for Advanced Neuroimaging, Charité-Universitätsmedizin, Berlin, Germany; Berlin School of Mind and Brain, Humboldt Universität zu Berlin, Germany; Cluster of Excellence NeuroCure, Charité-Universitätsmedizin, Berlin, Germany; Department of Psychology, Humboldt Universität zu Berlin, Berlin, Germany. Electronic address: haynes@bccn-berlin.de.
authors.forename: J-D
authors.initials: JD
authors.lastname: Haynes
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009778:Occipital Lobe / Q000502:physiology*; D010775:Photic Stimulation; D013702:Temporal Lobe / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology; D055815:Young Adult
keywords: Functional connectivity; Functional magnetic resonance imaging; Neural correlates of consciousness; Visual masking