Feature-Specific Attentional Priority Signals in Human Cortex

Abstract

Human can flexibly attend to a variety of stimulus dimensions, including spatial location and various features such as color and direction of motion. Although the locus of spatial attention has been hypothesized to be represented by priority maps encoded in several dorsal frontal and parietal areas, it is unknown how the brain represents attended features. Here we examined the distribution and organization of neural signals related to deployment of feature-based attention. Subjects viewed a compound stimulus containing two superimposed motion directions (or colors) and were instructed to perform an attention-demanding task on one of the directions (or colors). We found elevated and sustained functional magnetic resonance imaging response for the attention task compared with a neutral condition, without reliable differences in overall response amplitude between attending to different features. However, using multivoxel pattern analysis, we were able to decode the attended feature in both early visual areas (primary visual cortex to human motion complex hMTϩ) and frontal and parietal areas (e.g., intraparietal sulcus areas IPS1-IPS4 and frontal eye fields) that are commonly associated with spatial attention. Furthermore, analysis of the classifier weight maps showed that attending to motion and color evoked different patterns of activity, suggesting that different neuronal subpopulations in these regions are recruited for attending to different feature dimensions. Thus, our finding suggests that, rather than a purely spatial representation of priority, frontal and parietal cortical areas also contain multiplexed signals related to the priority of different nonspatial features.

Feature-Selective Attentional Modulations in Human Frontoparietal Cortex

“…We therefore conducted a second (independent) searchlight analysis where we trained a linear classifier to decode the participants' task set (i.e., attend-orientation vs attend-luminance) from multivoxel activation patterns measured within each searchlight neighborhood. This approach rests on the assumption that ROIs engaged in top-down control (1) should encode a representation of what feature participants are asked to attend and (2) can be used to identify neural sources of cognitive control, as has been demonstrated in several previous studies (Esterman et al, 2009;Liu et al, 2011;Riggall and Postle, 2012).…”

“…Based on earlier work (Esterman et al, 2009;Liu et al, 2011;Liu, 2016;Riggall and Postle, 2012), we reasoned that regions engaged in top-down control over visual selection would contain a representation of what task participants were instructed to perform, i.e., attend orientation vs. attend luminance. To this end, we trained a linear SVM to discriminate what task participants were instructed to perform (i.e., attend-orientation vs attend-luminance) from multivoxel activation patterns measured in searchlight neighborhoods centered on each gray matter voxel in the cortical sheet (see Materials and Methods, Searchlight definition of task-selective ROIs).…”

A Hierarchy of Attentional Priority Signals in Human Frontoparietal Cortex

“…nimh.nih.gov/pub/dist/doc/program_help/3dClustSim.html). More details of the group analysis pipeline have been reported in previous studies (Liu et al, 2011;Hou and Liu, 2012).…”

“…In the case of spatial attention (selection of spatial locations), the idea has been strongly supported by data from both single-unit physiology and neuroimaging (Moore, 2006;Serences and Yantis, 2006;Bisley and Goldberg, 2010). More recent studies using the functional magnetic resonance imaging (fMRI) multivariate decoding approach have suggested that these areas also represent attentional priority for features and objects (Liu et al, 2011;Guo et al, 2012;Hou and Liu, 2012). These findings suggest that the dorsal frontoparietal areas represent attentional priority for locations, features, and objects.…”

Recent developments in multivariate pattern analysis for functional MRI

“…To give MVPA a boarder scope, Kriegeskorte et al [66] proposed an approach aiming to bridge the usually from studies using block or slow event-related studies [17,60,64,67] , while the latter choice can be found in fast event-related studies [21,62,68,69] . Another alternative feature is coefficients from GLM using impulse response (IRF) basis functions [58,59] .…”