The neural bases of spatial attention and perceptual rhythms

Abstract

Attentional processes allow the brain to overcome its processing capacities limitations by enhancing relevant visual information and suppressing irrelevant information. Thus attention plays a critical role, shaping our perception of the world. Several models have been proposed to describe the neuronal bases of attention and its mechanistic underlyings. Recent electrophysiological evidence show that attentional processes rely on oscillatory brain activities that correlate with rhythmic changes in cognitive performance. In the present review, we first take a historical perspective on how attention is viewed, from the initial spotlight theory of attention to the recent dynamic view of attention selection and we review their supporting psychophysical evidence. Based on recent prefrontal electrophysiological evidence, we refine the most recent models of attention sampling by proposing a rhythmic and continuous model of attentional sampling. In particular, we show that attention involves a continuous exploration of space, shifting within and across visual hemifield at specific alpha and theta rhythms, independently of the current attentional load. In addition, we show that this prefrontal attentional spotlight implements conjointly selection and suppression mechanisms, and is captured by salient incoming items. Last, we argue that this attention spotlight implements a highly flexible alternation of attentional exploration and exploitation epochs, depending on ongoing task contingencies. In a last part, we review the local and network oscillatory mechanisms that correlate with rhythmic attentional sampling, describing multiple rhythmic generators and complex network interactions.

Revisiting Persistent Neuronal Activity During Covert Spatial Attention

“…Classically, the spotlight theory of attention assumes that attention is only focused at one location of space at a time [Eriksen and St. James, 1986 ; see the discussion in Posner and Petersen ( 1990 ), Gaillard and Ben Hamed ( 2020 )]. This view posits that it is possible to shift the spotlight of attention from one location to another, independent of the eye position and adjustment of its size to the attended location like a zoom lens.…”

“…In this context, covert attention can be considered as an instance of working memory as the information needed to be prioritized, whether feature-based or spatial, is by definition sustained, i.e., held in working memory (Desimone and Duncan, 1995 ). We will describe the structure and informational content of the observed neuronal activity in the deployment of covert attention, and discuss it in relation to the current views on the dynamic and rhythmic nature of attention [see Gaillard et al ( 2020 ), Gaillard and Ben Hamed ( 2020 ) for a review].…”

Periodic attention operates faster during more complex visual search

“…The frequency of attentional sampling reported across the literature shows large discrepancies [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. We propose that part of this heterogeneity is due to inconsistent attentional demands across tasks.…”

Non-invasive real-time access to spatial attention information from 3T fMRI BOLD signals

“…Visual attention is a cognitive process which allows to select visual stimuli in space for enhanced processing (Boynton, 2005; Gaillard and Ben Hamed, 2020). Spatial attention can be divided in two different processes: overt attention, whereby the eyes move towards the stimulus of interest, and covert attention, which is the process of shifting the focus of attention towards a visual stimulus while the eyes remain stable (Posner, 1980).…”

“…One reason for this is the fact that the precise informational content of covert functions can only be assessed indirectly from differed behavioral responses. Another reason pertains to the fact that recent accounts indicate that spatial attention, rather than being stable in space, is actually rhythmic, moving from one spatial location to another (Fiebelkorn et al, 2013; Gaillard et al, 2020; Gaillard and Ben Hamed, 2020; Landau and Fries, 2012). Several studies have been conducted in order to access covert visual attention in real-time.…”