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Free keywords:
fMRI; Multivoxel pattern analysis; Visuospatial attention; 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.
