Preparatory α-band oscillations reflect spatial gating independently of predictions regarding target identity

Abstract

Preparatory modulations of cortical α-band oscillations are a reliable index of the voluntary allocation of covert spatial attention. It is currently unclear whether attentional cues containing information about a target's identity (such as its visual orientation), in addition to its location, might additionally shape preparatory α modulations. Here, we explore this question by directly comparing spatial and feature-based attention in the same visual detection task while recording brain activity using magnetoencephalography (MEG). At the behavioral level, preparatory feature-based and spatial attention cues both improved performance and did so independently of each other. Using MEG, we replicated robust α lateralization following spatial cues: in preparation for a visual target, α power decreased contralaterally and increased ipsilaterally to the attended location. Critically, however, preparatory α lateralization was not significantly modulated by predictions regarding target identity, as carried via the behaviorally effective feature-based attention cues. Furthermore, nonlateralized α power during the cue-target interval did not differentiate between uninformative cues and cues carrying feature-based predictions either. Based on these results we propose that preparatory α modulations play a role in the gating of information between spatially segregated cortical regions and are therefore particularly well suited for spatial gating of information. The present work clarifies if and how human brain oscillations in the α-band support multiple types of anticipatory attention. Using magnetoencephalography, we show that posterior α-band oscillations are modulated by predictions regarding the spatial location of an upcoming visual target, but not by feature-based predictions regarding its identity, despite robust behavioral benefits. This provides novel insights into the functional role of preparatory α mechanisms and suggests a limited specificity with which they may operate.

Priority Switches in Visual Working Memory are Supported by Frontal Delta and Posterior Alpha Interactions

“…The initial encoding phase and the following first retention interval exhibited robust parieto-occipital alpha suppression, which was stronger contralateral compared with ipsilateral to the memory items. Such a lateralized difference in alpha suppression has been found before, both during visual attention to anticipated target locations ( Sauseng et al 2005b ; Thut et al 2006 ; Spaak et al 2015 ; Wildegger et al 2017 ), and during VWM maintenance ( Fukuda et al 2015 ; Myers et al 2015b ; Schneider et al 2015 , 2016 ; van Driel et al 2017 ). Posterior alpha lateralization during working memory maintenance presumably serves to control the spatiotopic access to recently encoded relevant visual information ( Myers et al 2015b ), which can subsequently be processed further in object-selective cortex ( Zumer et al 2014 ).…”

One Thing Leads to Another: Anticipating Visual Object Identity Based on Associative-Memory Templates

“…Interestingly, a previous study in which participants could prepare for a specific defining feature of a forthcoming target grating (Wildegger, van Ede, Woolrich, Gillebert, & Nobre, 2017) found no evidence for modulations within the alpha-band. The apparent discrepancy with the current finding could be due to statistical variability (i.e.…”

Enhanced spatial focusing increases feature-based selection in unattended locations

“…A psychophysical study shows that the spatial focus of attention needs between 200–500 ms to narrow down onto a target location, and inhibit attentional selection at distant locations (like the probe’s location) 48 . Neural measures of preparatory alpha oscillations suggest as well that subjects need at least 300–400 ms before they build a stable location bias (i.e., alpha lateralization) 49 . Subjects were explicitly encouraged to covertly anchor their attention at the position of the outline prior to target onset to improve their performance.…”