title: Contextual Feedback to Superficial Layers of V1.
abstract: Neuronal cortical circuitry comprises feedforward, lateral, and feedback projections, each of which terminates in distinct cortical layers [1-3]. In sensory systems, feedforward processing transmits signals from the external world into the cortex, whereas feedback pathways signal the brain's inference of the world [4-11]. However, the integration of feedforward, lateral, and feedback inputs within each cortical area impedes the investigation of feedback, and to date, no technique has isolated the feedback of visual scene information in distinct layers of healthy human cortex. We masked feedforward input to a region of V1 cortex and studied the remaining internal processing. Using high-resolution functional brain imaging (0.8 mm(3)) and multivoxel pattern information techniques, we demonstrate that during normal visual stimulation scene information peaks in mid-layers. Conversely, we found that contextual feedback information peaks in outer, superficial layers. Further, we found that shifting the position of the visual scene surrounding the mask parametrically modulates feedback in superficial layers of V1. Our results reveal the layered cortical organization of external versus internal visual processing streams during perception in healthy human subjects. We provide empirical support for theoretical feedback models such as predictive coding [10, 12] and coherent infomax [13] and reveal the potential of high-resolution fMRI to access internal processing in sub-millimeter human cortex.
authors.affiliation: Centre for Cognitive Neuroimaging (CCNi), Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, 58 Hillhead Street, G12 8QB Scotland, UK. Electronic address: lars.muckli@glasgow.ac.uk.
authors.forename: Lars
authors.initials: L
authors.lastname: Muckli
authors.affiliation: Faculty of Psychology and Neuroscience, Department of Cognitive Neurosciences, Maastricht University, Oxfordlaan 55, 6229 EV Maastricht, the Netherlands; Center for Magnetic Resonance Research (CMRR), Department of Radiology, University of Minnesota, 2021 Sixth Street SE, Minneapolis, MN 55455, USA.
authors.forename: Federico
authors.initials: F
authors.lastname: De Martino
authors.affiliation: Centre for Cognitive Neuroimaging (CCNi), Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, 58 Hillhead Street, G12 8QB Scotland, UK.
authors.forename: Luca
authors.initials: L
authors.lastname: Vizioli
authors.affiliation: Centre for Cognitive Neuroimaging (CCNi), Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, 58 Hillhead Street, G12 8QB Scotland, UK.
authors.forename: Lucy S
authors.initials: LS
authors.lastname: Petro
authors.affiliation: School of Psychology, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
authors.forename: Fraser W
authors.initials: FW
authors.lastname: Smith
authors.affiliation: Center for Magnetic Resonance Research (CMRR), Department of Radiology, University of Minnesota, 2021 Sixth Street SE, Minneapolis, MN 55455, USA.
authors.forename: Kamil
authors.initials: K
authors.lastname: Ugurbil
authors.affiliation: Faculty of Psychology and Neuroscience, Department of Cognitive Neurosciences, Maastricht University, Oxfordlaan 55, 6229 EV Maastricht, the Netherlands; Department of Neuroimaging and Neuromodeling, Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands.
authors.forename: Rainer
authors.initials: R
authors.lastname: Goebel
authors.affiliation: Center for Magnetic Resonance Research (CMRR), Department of Radiology, University of Minnesota, 2021 Sixth Street SE, Minneapolis, MN 55455, USA.
authors.forename: Essa
authors.initials: E
authors.lastname: Yacoub
mesh_terms: D025461:Feedback, Physiological; D006801:Humans; D008279:Magnetic Resonance Imaging; D010775:Photic Stimulation; D014793:Visual Cortex / Q000502:physiology*; D014795:Visual Pathways