Article

Cue-invariant networks for figure and background processing in human visual cortex

Smith-Kettlewell Eye Research Institute, San Francisco, California, United States
The Journal of Neuroscience : The Official Journal of the Society for Neuroscience (Impact Factor: 6.75). 12/2006; 26(45):11695-708. DOI: 10.1523/JNEUROSCI.2741-06.2006
Source: PubMed

ABSTRACT Lateral occipital cortical areas are involved in the perception of objects, but it is not clear how these areas interact with first tier visual areas. Using synthetic images portraying a simple texture-defined figure and an electrophysiological paradigm that allows us to monitor cortical responses to figure and background regions separately, we found distinct neuronal networks responsible for the processing of each region. The figure region of our displays was tagged with one temporal frequency (3.0 Hz) and the background region with another (3.6 Hz). Spectral analysis was used to separate the responses to the two regions during their simultaneous presentation. Distributed source reconstructions were made by using the minimum norm method, and cortical current density was measured in a set of visual areas defined on retinotopic and functional criteria with the use of functional magnetic resonance imaging. The results of the main experiments, combined with a set of control experiments, indicate that the figure region, but not the background, was routed preferentially to lateral cortex. A separate network extending from first tier through more dorsal areas responded preferentially to the background region. The figure-related responses were mostly invariant with respect to the texture types used to define the figure, did not depend on its spatial location or size, and mostly were unaffected by attentional instructions. Because of the emergent nature of a segmented figure in our displays, feedback from higher cortical areas is a likely candidate for the selection mechanism by which the figure region is routed to lateral occipital cortex.

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    • "These results are consistent across participants and also agree with the recent single unit and fMRI literature. As we have noted previously (Appelbaum et al., 2006, Cottereau et al., 2010b), the availability of individually determined functional ROIs makes it possible to pool data across participants in a way that respects individual differences in the location, size and shape of different functional areas. While area V1 and V2 have a consistent relationship to the anatomical landmark of the calcarine sulcus (Hinds et al., 2009), higher-order areas, such as V3A show a large error of variation in their location. "
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    Human Brain Mapping 11/2012; 33(11):2694-713. DOI:10.1002/hbm.21394
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    • "The shape representation in the LOC is also tuned for small shape changes in the outline of objects (Gillebert et al., 2009; Panis et al., 2008). Our previous source-imaging studies using frequency tagging have suggested that the LOC is tuned for the configuration of a small figure on a larger background (Appelbaum et al., 2010) and that LOC responses to figures are largely cue-invariant (Appelbaum et al., 2006, 2012). Cue-invariance in LOC has also been found with fMRI (Grill-Spector et al., 1998). "
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    • "Although we treated LO as a unitary figure-related entity in this study, an interesting possibility is that it too can be broken down into figure and background responses. A literal interpretation of the view that LO represents figures and not backgrounds (Appelbaum et al., 2006; Goh et al., 2004) argues against this possibility. However, the observation of coarse retinotopy in LO (Strother, Aldcroft, Lavell, & Vilis, 2010; Sayres & Grill-Spector, 2008; Larsson & Heeger, 2006) means that this conceptualization of LO may be oversimplified and that it may be possible to delineate " figure " and " background " fMRI responses in LO in future studies of figure–ground representation and form-based perceptual memory. "
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