title: Orientation pop-out processing in human visual cortex.
abstract: Visual stimuli can "pop out" if they are different to their background. There has been considerable debate as to the role of primary visual cortex (V1) versus higher visual areas (esp. V4) in pop-out processing. Here we parametrically modulated the relative orientation of stimuli and their backgrounds to investigate the neural correlates of pop-out in visual cortex while subjects were performing a demanding fixation task in a scanner. Whole brain and region of interest analyses confirmed a representation of orientation contrast in extrastriate visual cortex (V4), but not in striate visual cortex (V1). Thus, although previous studies have shown that human V1 can be involved in orientation pop-out, our findings demonstrate that there are cases where V1 is "blind" and pop-out detection is restricted to higher visual areas. Pop-out processing is presumably a distributed process across multiple visual regions.
authors.affiliation: Bernstein Center for Computational Neuroscience Berlin, Charité-Universitätsmedizin Berlin, Germany; Max-Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; Department of Neurology, Otto-von-Guericke University Magdeburg, Germany. Electronic address: carsten.bogler@bccn-berlin.de.
authors.forename: Carsten
authors.initials: C
authors.lastname: Bogler
authors.affiliation: Max-Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; Department of Neurology, Otto-von-Guericke University Magdeburg, Germany; Melbourne School of Psychological Sciences, The University of Melbourne, Australia.
authors.forename: Stefan
authors.initials: S
authors.lastname: Bode
authors.affiliation: Bernstein Center for Computational Neuroscience Berlin, Charité-Universitätsmedizin Berlin, Germany; Max-Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; Department of Neurology, Otto-von-Guericke University Magdeburg, Germany. Electronic address: haynes@bccn-berlin.de.
authors.forename: John-Dylan
authors.initials: JD
authors.lastname: Haynes
mesh_terms: D000328:Adult; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009949:Orientation / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D014793:Visual Cortex / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: Functional MRI; Pop-out; Visual attention; Visual cortex