Abstract
Selective attention mechanisms allow us to focus on information that is relevant to the current behavior and, equally important, ignore irrelevant information. An influential model proposes that oscillatory neural activity in the alpha band serves as an active functional inhibitory mechanism. Recent studies have shown that, in the same way that attention can be selectively oriented to bias sensory processing in favor of relevant stimuli in perceptual tasks, it is also possible to retrospectively orient attention to internal representations held in working memory. However, these studies have not explored the associated oscillatory phenomena. In the current study, we analysed the patterns of neural oscillatory activity recorded with magnetoencephalography while participants performed a change detection task, in which a spatial retro-cue was presented during the maintenance period, indicating which item or items were relevant for subsequent retrieval. Participants benefited from retro-cues in terms of accuracy and reaction time. Retro-cues also modulated oscillatory activity in the alpha and gamma frequency bands. We observed greater alpha activity in a ventral visual region ipsilateral to the attended hemifield, thus supporting its suppressive role, i.e. a functional disengagement of task-irrelevant regions. Accompanying this modulation, we found an increase in gamma activity contralateral to the attended hemifield, which could reflect attentional orienting and selective processing. These findings suggest that the oscillatory mechanisms underlying attentional orienting to representations held in working memory are similar to those engaged when attention is oriented in the perceptual space.
Highlights
Even though we are constantly exposed to an environment full of sensory stimuli, we are able to selectively process relevant events most of the time (Asplund et al, 2010; Anton-Erxleben & Carrasco, 2013)
Differences in filtering efficiency, i.e. the ability to hold critical information while ignoring irrelevant information, has been shown to contribute to individual differences in working memory (WM) (Vogel et al, 2005; Fukuda & Vogel, 2009; Fukuda et al, 2010; Jost et al, 2011). Whereas these studies have focused on how selective attention mechanisms are engaged for gating the encoding of relevant items (Kuo et al, 2011) or relevant features (Poch et al, 2010) into WM, several studies have shown that, in the same way that attention can be selectively oriented to bias sensory processing in favor of relevant stimuli in perceptual tasks, it is possible to retrospectively orient attention to internal representations held in WM (Giffrin & Nobre, 2003; Landman et al, 2003; Makovski & Jiang, 2007; Matsukura et al, 2007; Makovski et al, 2008; Sligte et al, 2008)
Such studies have demonstrated that, when attention is directed to one hemifield, with tasks that vary in stimulus modality, there is an increase in alpha activity in the hemisphere ipsilateral to the attended hemifield, and a decrease in the contralateral one (Worden et al, 2000; Thut et al, 2006; Freunberger et al, 2008; Siegel et al, 2008; Rihs et al, 2009; Sauseng et al, 2009; van Dijk et al, 2010; Haegens et al, 2010; Huang & Sekuler, 2010; Snyder & Foxe, 2010; van Ede et al, 2011; Grent-’t-Jong et al, 2011; Handel et al, 2011; Bauer et al, 2012a,b; Capilla et al, 2014)
Summary
Even though we are constantly exposed to an environment full of sensory stimuli, we are able to selectively process relevant events most of the time (Asplund et al, 2010; Anton-Erxleben & Carrasco, 2013). Differences in filtering efficiency, i.e. the ability to hold critical information while ignoring irrelevant information, has been shown to contribute to individual differences in WM (Vogel et al, 2005; Fukuda & Vogel, 2009; Fukuda et al, 2010; Jost et al, 2011) Whereas these studies have focused on how selective attention mechanisms are engaged for gating the encoding of relevant items (Kuo et al, 2011) or relevant features (Poch et al, 2010) into WM, several studies have shown that, in the same way that attention can be selectively oriented to bias sensory processing in favor of relevant stimuli in perceptual tasks, it is possible to retrospectively orient attention to internal representations held in WM (Giffrin & Nobre, 2003; Landman et al, 2003; Makovski & Jiang, 2007; Matsukura et al, 2007; Makovski et al, 2008; Sligte et al, 2008). In light of these observations, it would be interesting to determine whether the oscillatory patterns in the gamma band associated with orienting attention to external perceptual representations can be observed when attention is oriented to internal representations in WM
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