Reduced V1 activity to local image patches that are inconsistent with the global scene interpretation
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1
University of New South Wales, School of Psychology, Australia
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2
University of Minnesota, Department of Psychology, United States
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3
Korea University, Department of Brain and Cognitive Engineering, Republic of Korea
Background:
Human visual cortex is hierarchically organised, with low-level areas encoding spatially localised fine image details that are combined in higher-level areas selective for increasingly abstract and global image properties. However, a globally coherent interpretation cannot always accommodate the complete ensemble of local image details, and the consequences of this mismatch for local encoding remains unclear. Here, we investigate the effect of such local/global discrepancy on the response magnitude of local image regions in human primary visual cortex (V1).
Methods:
We used functional magnetic resonance imaging (fMRI) at 7 Tesla to measure the blood-oxygen level-dependent (BOLD) signal in human V1 (n=5). In a rapid event-related design, participants viewed an array of 32 apertures that tiled the visual field. On each trial, the majority (19/32) of apertures showed patches from a single natural image (yielding a dominant perceptual interpretation) while the remaining apertures each showed a patch from a different natural image. Using high-resolution imaging (1mm isotropic voxels) and a separate aperture region localiser session, we measured the V1 response to each aperture location while it was displaying patches that were consistent (coherent) or inconsistent (non-coherent) with the dominant global interpretation.
Results:
We find that the V1 response to apertures containing local image information inconsistent with the global scene interpretation was significantly lower than when the same local image structure was coherent with the global percept.
Discussion:
The current results are most readily interpreted in a 'sharpening' framework of visual area interaction, in which globally inconsistent local features are suppressed relative to those that are compatible with the global interpretation. The scenarios in which this strategy is adopted rather than an alternative, in which the globally consistent elements are suppressed due to the predictability, remain to be clarified.
Acknowledgements
We thank A Grant, C Qui, and M-P Schallmo for scanning assistance. This work was supported by ONR (N000141210883), the WCU (World Class University) program funded by the Ministry of Education, Science, and Technology through the National Research Foundation of Korea (R31-10008), the Keck Foundation, and NIH (P30-NS076408, P41-EB015894, P30-EY011374, R21-NS075525).
Keywords:
fMRI,
Visual Perception,
Visual Cortex,
Grouping,
Visual Fields
Conference:
ACNS-2013 Australasian Cognitive Neuroscience Society Conference, Clayton, Melbourne, Australia, 28 Nov - 1 Dec, 2013.
Presentation Type:
Poster
Topic:
Sensation and Perception
Citation:
Mannion
DJ,
Kersten
DJ and
Olman
CA
(2013). Reduced V1 activity to local image patches that are inconsistent with the global scene interpretation.
Conference Abstract:
ACNS-2013 Australasian Cognitive Neuroscience Society Conference.
doi: 10.3389/conf.fnhum.2013.212.00066
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Received:
15 Oct 2013;
Published Online:
25 Nov 2013.
*
Correspondence:
Dr. Damien J Mannion, University of New South Wales, School of Psychology, Sydney, Australia, d.mannion@unsw.edu.au