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Jason T. Arita, Geoffrey F. Woodman; Do gamma-band oscillations bind features when attention is focused on multiple-feature objects during visual search?. Journal of Vision 2008;8(6):998. doi: 10.1167/8.6.998.
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© ARVO (1962-2015); The Authors (2016-present)
Many theories propose that activity in the gamma band is responsible for solving the binding problem when viewing arrays of multi-feature objects. For example, synchronized firing of cells coding for the features of an attended object are thought to underlie our perception of bound object representations during visual search. However, the evidence for such an oscillatory binding mechanism is sparse. In the present study we analyzed EEG data collected during a demanding visual search task requiring serial shifts of attention. Event-related potentials (ERPs) time-locked to the onset of the search array allowed us to measure when attention was focused on possible target items. We predicted that if gamma activity binds the features of these objects, then we should be able to measure a burst of gamma-band power accompanying the focusing of attention on the complex objects in the search arrays. Using a Morlet's wavelet time-frequency analysis we measured the power in the gamma band across each trial. We did not observe any clear modulation of gamma-band power following the onset of the search array despite the indication of ERP components showing when attention was deployed to the objects in the search arrays. These findings are inconsistent with the hypothesis that gamma-band oscillations bind together the features of an object embedded in a cluttered visual scene.
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