Abstract
Previous studies demonstrated that long-term memory related to object-position in natural scenes guides visuo-spatial attention during subsequent search. Memory-guided attention has been associated with the activation of memory regions (the medial-temporal cortex) and with the fronto-parietal attention network. Notably, these circuits represent external locations with different frames of reference: egocentric (i.e., eyes/head-centered) in the dorsal attention network vs. allocentric (i.e., world/scene-centered) in the medial temporal cortex. Here we used behavioral measures and fMRI to assess the contribution of egocentric and allocentric spatial information during memory-guided attention. At encoding, participants were presented with real-world scenes and asked to search for and memorize the location of a high-contrast target superimposed in half of the scenes. At retrieval, participants viewed again the same scenes, now all including a low-contrast target. In scenes that included the target at encoding, the target was presented at the same scene-location. Critically, scenes were now shown either from the same or different viewpoint compared with encoding. This resulted in a memory-by-view design (target seen/unseen x same/different view), which allowed us teasing apart the role of allocentric vs. egocentric signals during memory-guided attention. Retrieval-related results showed greater search-accuracy for seen than unseen targets, both in the same and different views, indicating that memory contributes to visual search notwithstanding perspective changes. This view-change independent effect was associated with the activation of the left lateral intra-parietal sulcus. Our results demonstrate that this parietal region mediates memory-guided attention by taking into account allocentric/scene-centered information about the objects' position in the external world.
Highlights
Visuo-spatial attention plays a key role in our everyday experience, allowing us to select relevant information to pursue current behavioral goals
These results indicate that the participants successfully memorized the target position during the encoding phase
The participants had again to report the orientation of the target-bar, but this appeared in the scene at a much lower contrast than at encoding
Summary
Visuo-spatial attention plays a key role in our everyday experience, allowing us to select relevant information to pursue current behavioral goals. The imaging results revealed that the hippocampus (HPC) and the adjacent parahippocampal cortex activated significantly more in valid vs neutral trials, selectively for memory- vs visually-guided spatial orienting These findings demonstrated that memory-guided attention engages the fronto-parietal networks, traditionally associated with perceptual attention (e.g., see Cabeza et al 2008; Rosen et al 2015; see Sestieri et al 2017), as well as medial temporal regions typically associated with the processing of scenes, binding of contextual information and retrieval from LTM (Diana et al 2007; Eichenbaum et al 2007; Epstein et al 2003)
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