title: Incremental integration of global contours through interplay between visual cortical areas.
abstract: The traditional view on visual processing emphasizes a hierarchy: local line segments are first linked into global contours, which in turn are assembled into more complex forms. Distinct from this bottom-up viewpoint, here we provide evidence for a theoretical framework whereby objects and their parts are processed almost concurrently in a bidirectional cortico-cortical loop. By simultaneous recordings from V1 and V4 in awake monkeys, we found that information about global contours in a cluttered background emerged initially in V4, started ∼40 ms later in V1, and continued to develop in parallel in both areas. Detailed analysis of neuronal response properties implicated contour integration to emerge from both bottom-up and reentrant processes. Our results point to an incremental integration mechanism: feedforward assembling accompanied by feedback disambiguating to define and enhance the global contours and to suppress background noise. The consequence is a parallel accumulation of contour information over multiple cortical areas.
authors.affiliation: State Key Laboratory of Cognitive Neuroscience and Learning, IDG/McGovern Institute for Brain Research, and Center for Collaboration and Innovation in Brain and Learning Sciences, Beijing Normal University, Beijing 100875, China.
authors.forename: Minggui
authors.initials: M
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Cognitive Neuroscience and Learning, IDG/McGovern Institute for Brain Research, and Center for Collaboration and Innovation in Brain and Learning Sciences, Beijing Normal University, Beijing 100875, China.
authors.forename: Yin
authors.initials: Y
authors.lastname: Yan
authors.affiliation: School of Biomedical Engineering, Drexel University, Philadelphia, PA 19104, USA.
authors.forename: Xiajing
authors.initials: X
authors.lastname: Gong
authors.affiliation: Laboratory of Neurobiology, The Rockefeller University, New York, NY 10065, USA.
authors.forename: Charles D
authors.initials: CD
authors.lastname: Gilbert
authors.affiliation: School of Biomedical Engineering, Drexel University, Philadelphia, PA 19104, USA.
authors.forename: Hualou
authors.initials: H
authors.lastname: Liang
authors.affiliation: State Key Laboratory of Cognitive Neuroscience and Learning, IDG/McGovern Institute for Brain Research, and Center for Collaboration and Innovation in Brain and Learning Sciences, Beijing Normal University, Beijing 100875, China. Electronic address: liwu@bnu.edu.cn.
authors.forename: Wu
authors.initials: W
authors.lastname: Li
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D015350:Contrast Sensitivity / Q000502:physiology*; D008253:Macaca mulatta; D008297:Male; D010775:Photic Stimulation / Q000379:methods*; D014793:Visual Cortex / Q000502:physiology*