This work is supported by funding from the Netherlands Organization of Scientific Research (NWO) and the Advanced Investigator Grant from the European Research Council (ERC) to V. A. F. L.
Two critical periods in early visual cortex during figure–ground segregation
Article first published online: 29 SEP 2012
© 2012 The Authors. Brain and Behavior published by Wiley Periodicals, Inc.
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Brain and Behavior
Volume 2, Issue 6, pages 763–777, November 2012
How to Cite
Brain and Behavior 2012; 2(6): 763–777
- Issue published online: 9 NOV 2012
- Article first published online: 29 SEP 2012
- Manuscript Accepted: 1 AUG 2012
- Manuscript Revised: 30 JUL 2012
- Manuscript Received: 3 MAY 2012
- Netherlands Organization of Scientific Research (NWO)
- Advanced Investigator Grant from the European Research Council (ERC)
- EEG ;
- scene segmentation;
- TMS ;
- visual perception
The ability to distinguish a figure from its background is crucial for visual perception. To date, it remains unresolved where and how in the visual system different stages of figure–ground segregation emerge. Neural correlates of figure border detection have consistently been found in early visual cortex (V1/V2). However, areas V1/V2 have also been frequently associated with later stages of figure–ground segregation (such as border ownership or surface segregation). To causally link activity in early visual cortex to different stages of figure–ground segregation, we briefly disrupted activity in areas V1/V2 at various moments in time using transcranial magnetic stimulation (TMS). Prior to stimulation we presented stimuli that made it possible to differentiate between figure border detection and surface segregation. We concurrently recorded electroencephalographic (EEG) signals to examine how neural correlates of figure–ground segregation were affected by TMS. Results show that disruption of V1/V2 in an early time window (96–119 msec) affected detection of figure stimuli and affected neural correlates of figure border detection, border ownership, and surface segregation. TMS applied in a relatively late time window (236–259 msec) selectively deteriorated performance associated with surface segregation. We conclude that areas V1/V2 are not only essential in an early stage of figure–ground segregation when figure borders are detected, but subsequently causally contribute to more sophisticated stages of figure–ground segregation such as surface segregation.