title: Texture Segregation Causes Early Figure Enhancement and Later Ground Suppression in Areas V1 and V4 of Visual Cortex.
abstract: Segregation of images into figures and background is fundamental for visual perception. Cortical neurons respond more strongly to figural image elements than to background elements, but the mechanisms of figure-ground modulation (FGM) are only partially understood. It is unclear whether FGM in early and mid-level visual cortex is caused by an enhanced response to the figure, a suppressed response to the background, or both.We studied neuronal activity in areas V1 and V4 in monkeys performing a texture segregation task. We compared texture-defined figures with homogeneous textures and found an early enhancement of the figure representation, and a later suppression of the background. Across neurons, the strength of figure enhancement was independent of the strength of background suppression.We also examined activity in the different V1 layers. Both figure enhancement and ground suppression were strongest in superficial and deep layers and weaker in layer 4. The current-source density profiles suggested that figure enhancement was caused by stronger synaptic inputs in feedback-recipient layers 1, 2, and 5 and ground suppression by weaker inputs in these layers, suggesting an important role for feedback connections from higher level areas. These results provide new insights into the mechanisms for figure-ground organization.
authors: Department of Vision and Cognition, Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, 1105 BA, the Netherlands Department of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6DE, UK Sainsbury Wellcome Centre for Neural Circuits and Behaviour, University College London, London, W1T 4JG, UK.
authors: Jasper
authors: J
authors: Poort
authors: Department of Vision and Cognition, Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, 1105 BA, the Netherlands.
authors: Matthew W
authors: MW
authors: Self
authors: Department of Vision and Cognition, Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, 1105 BA, the Netherlands.
authors: Bram
authors: B
authors: van Vugt
authors: Department of Vision and Cognition, Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, 1105 BA, the Netherlands.
authors: Hemi
authors: H
authors: Malkki
authors: Department of Vision and Cognition, Netherlands Institute for Neuroscience, An Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, 1105 BA, the Netherlands Department of Integrative Neurophysiology, Centre for Neurogenomics and Cognitive Research, Vrije Universiteit, Amsterdam, 1081 HV,  the Netherlands Psychiatry Department, Academic Medical Center, Amsterdam, 1105 AZ, the Netherlands.
authors: Pieter R
authors: PR
authors: Roelfsema
mesh_terms: D000200:Action Potentials; D000818:Animals; D001288:Attention / Q000502:physiology; D004567:Electrodes, Implanted; D053483:Eye Movement Measurements; D000882:Haplorhini; D009474:Neurons / Q000502:physiology*; D009483:Neuropsychological Tests; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D012815:Signal Processing, Computer-Assisted; D014793:Visual Cortex / Q000502:physiology*
keywords: cortical layers; figure–ground segmentation; perceptual organization; vision; visual cortex