Activity in Human Visual and Parietal Cortex Reveals Object-Based Attention in Working Memory

Abstract

Visual attention enables observers to select behaviorally relevant information based on spatial locations, features, or objects. Attentional selection is not limited to physically present visual information, but can also operate on internal representations maintained in working memory (WM) in service of higher-order cognition. However, only little is known about whether attention to WM contents follows the same principles as attention to sensory stimuli. To address this question, we investigated in humans whether the typically observed effects of object-based attention in perception are also evident for object-based attentional selection of internal object representations in WM. In full accordance with effects in visual perception, the key behavioral and neuronal characteristics of object-based attention were observed in WM. Specifically, we found that reaction times were shorter when shifting attention to memory positions located on the currently attended object compared with equidistant positions on a different object. Furthermore, functional magnetic resonance imaging and multivariate pattern analysis of visuotopic activity in visual (areas V1-V4) and parietal cortex revealed that directing attention to one position of an object held in WM also enhanced brain activation for other positions on the same object, suggesting that attentional selection in WM activates the entire object. This study demonstrated that all characteristic features of object-based attention are present in WM and thus follows the same principles as in perception.

Layer-specificity in the effects of attention and working memory on activity in primary visual cortex

“…It has remained less clear if working memory also relies on persistent activity in early visual cortical areas12. On the one hand, fMRI studies in humans reveal signatures of the items in working memory in higher but also in lower visual areas74749. Indeed, it is possible to decode the stimulus in memory from early visual areas by analysing the pattern of the fMRI signal across multiple voxels1550, even when the visually driven fMRI response has decayed back to baseline5152.…”

Organization and evolution of parieto-frontal processing streams in macaque monkeys and humans

“…Hemispheric asymmetries supporting an inter-hemispheric competition in attentional control were also observed, since only the right SPL-1 and left IPS-2 (with FEF) generate contralateral attention signals stronger than their contralateral corresponding regions. In some of these topographic maps, priority shapes the activation profile (Jerde et al, 2012) along a rostrocaudal and inferior-superior gradient representing maintenance of saccade planning, covert attention, and working memory (see also Peters et al, 2015), and defines prioritized maps of space. These maps can be modulated by reward-based mechanisms (Chelazzi et al, 2014).…”

Object-based attention prioritizes working memory contents at a theta rhythm

“…For example, both behavioral and neuroimaging studies have shown that spatial attention can also be directed to internally stored locations (Awh, Jonides, & Reuter-Lorenz, 1998) and that attentional shifts in perception and WM involve similar brain regions (Bledowski, Rahm, & Rowe, 2009;Nobre et al, 2004). Recently, we have demonstrated that also the principle of objectbased attention is used in WM (Peters, Kaiser, Rahm, & Bledowski, 2015) by adapting the perceptual paradigm of Egly et al (Egly et al, 1994) to WM. Participants had to memorize the exact location of two objects' endpoints which changed their position across trials.…”

“…Until now, it has remained unclear whether attentional sampling is specific to the selection of perceptual information or whether it constitutes a more general mechanism of information processing in human cognition. Based on the findings of rhythmic fluctuations of object-based attention in a perceptual paradigm (Fiebelkorn et al, 2013) and object-based attention effects in WM (Peters et al, 2015), the present study assessed whether attentional sampling also operates on information that is not externally present but represented internally, in WM. We employed a variant of our previous paradigm (Peters et al, 2015) and varied the interval between attentional cue and probe with a high temporal resolution to study the temporal trajectory of object-based attention in WM.…”