Beyond topographic representation: Decoding visuospatial attention from local activity patterns in the human frontal cortex

Abstract

The ability to detect where a person is attending is fundamental for brain-computer-interfaces. We explore how the attentional focus can be decoded from brain signals noninvasively acquired with functional magnetic resonance imaging (fMRI). Several cortical regions have previously been reported to have topographic maps reflecting the focus of visual attention. Interestingly, attentional maps were observed to be gradually less topographic when moving from early visual areas toward extra-occipital areas. Recent studies suggested that this might indicate a shift from topographically represented local processing to a global processing dominated by laterality. However, it remains unclear, to which extent the topographical representation of a region characterizes its quality to encode visuospatial attention. Here we addressed this problem by applying multivoxel pattern analysis to fMRI signals. In combination with a cortical surface-based mapping of spatial preference, our analysis revealed a broad cortical network that locally contains information about the locus of visual attention. The informative regions are not restricted to topographic areas, but even in frontal areas, where topographic organization is almost indiscernible, the attentional locus can be decoded from brain activity. Specifically, we find attentional information in the right middle frontal gyrus and the right ventrolateral prefrontal cortex. Furthermore, in these two areas information is sufficient to distinguish attentional loci within the ipsi- as well as the contra-lateral visual hemifields. The laterality dominance decreases when moving from occipital to frontal areas. Our results suggest that information about visuospatial attention is encoded beyond topographically organized regions by local patterns of brain activity

Decoding the Contents of Visual Short-Term Memory from Human Visual and Parietal Cortex

“…Consistent with this, PPC is believed to be involved in encoding of attention and saliency processing (Bisley and Goldberg, 2006;Bogler et al, 2011). It has been shown that PPC contains a retinotopic representation of the contralateral visual field (Sereno et al, 2001) and even that it has information about spatial attention in the ipsilateral visual field (Kalberlah et al, 2011). Our findings suggest that these contralateral and ipsilateral representations of visual space may also be capable of representing visual working memory content.…”

Coding of Visual, Auditory, Rule, and Response Information in the Brain: 10 Years of Multivoxel Pattern Analysis

“…In one study, radial and concentric patterns had been associated with differential button presses during training, although during scanning, participants performed an unrelated task (Mayhew et al, 2010). In all other cases, any button press responses given by participants were orthogonal (Mayhew & Kourtzi, 2013) or unrelated (Pollmann et al, 2014;Reverberi et al, 2012a;Kalberlah et al, 2011;Mayhew et al, 2010) to the visual discrimination.…”

“…We excluded any papers in which there were obvious associations between our task features, and in our stricter analysis, we also excluded any studies in which higher-level features such as semantic category differed between decoded items, or cases where items might evoke representations of associated motor actions. The remaining points of visual discrimination in the motor cortex were for discrimination between Gabor patches differing in color and spatial frequency (Pollmann, Zinke, Baumgartner, Geringswald, & Hanke, 2014), the spatial location of a target (Kalberlah, Chen, Heinzle, & Haynes, 2011), radial versus concentric glass patterns (Mayhew & Kourtzi, 2013;Mayhew, Li, Storrar, Tsvetanov, & Kourtzi, 2010), and between two abstract shapes cuing the same rule (Reverberi, Gorgen, & Haynes, 2012a). In one study, radial and concentric patterns had been associated with differential button presses during training, although during scanning, participants performed an unrelated task (Mayhew et al, 2010).…”

Multivariate decoding of fMRI data

“…Instead, we would be able to identify even spatially anisotropic distributions of cells that code for specific attended subregions of the visual field. In an fM-RI study [20], participants shifted their visuospatial attention toward cued targets (. Fig.…”

“…7a). MVPA techniques revealed that, a few seconds before [20] and [10] the decision was consciously made, highlevel control regions including lateral and medial frontopolar cortex, and precuneus/posterior cingulate, already began to encode the content of the upcoming decision in their local spatial patterns of activity, despite showing no overall increase in fMRI signal (. Fig.…”