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Cereb Cortex. 2015 Sep;25(9):2828-41. doi: 10.1093/cercor/bhu078. Epub 2014 Apr 25.

Determinants of Global Color-Based Selection in Human Visual Cortex.

Author information

1
Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany.
2
Department of Experimental Psychology, Ghent University, 9000 Ghent, Belgium.
3
Department of Neurology, Otto-von-Guericke University, 39120 Magdeburg, Germany.
4
Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany Department of Neurology, Otto-von-Guericke University, 39120 Magdeburg, Germany.

Abstract

Feature attention operates in a spatially global way, with attended feature values being prioritized for selection outside the focus of attention. Accounts of global feature attention have emphasized feature competition as a determining factor. Here, we use magnetoencephalographic recordings in humans to test whether competition is critical for global feature selection to arise. Subjects performed a color/shape discrimination task in one visual field (VF), while irrelevant color probes were presented in the other unattended VF. Global effects of color attention were assessed by analyzing the response to the probe as a function of whether or not the probe's color was a target-defining color. We find that global color selection involves a sequence of modulations in extrastriate cortex, with an initial phase in higher tier areas (lateral occipital complex) followed by a later phase in lower tier retinotopic areas (V3/V4). Importantly, these modulations appeared with and without color competition in the focus of attention. Moreover, early parts of the modulation emerged for a task-relevant color not even present in the focus of attention. All modulations, however, were eliminated during simple onset-detection of the colored target. These results indicate that global color-based attention depends on target discrimination independent of feature competition in the focus of attention.

KEYWORDS:

MEG; attention; color; human; visual

PMID:
24770709
DOI:
10.1093/cercor/bhu078
[Indexed for MEDLINE]

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