Large-scale functional networks underlying visual attention

Attention networks are loosely defined as the regions of the brain which interact to control behaviour during attentional tasks, but the specific definition of attention networks varies between research programs based on task demands and modalities. The Attention Network Task was designed to exemplify three aspects of attention, alerting, orienting, and executive control, using a visual cueing paradigm. Its proponents propose a system of networks which underlies these aspects. It is debated whether there exists a unified system of networks which underlies attention independently of other cognitive and sensory processing systems. We review the evidence for an attention system within the domain of visual attention. Neuroimaging research using fMRI, EEG, MEG, and others across a variety of tasks attributed to attention, visual cueing, visual search, and divided attention, is compared. This concludes with a discussion on the limitations of an independent "attention system" for describing how the brain flexibly controls many abilities attributed to visual attention.