The effects of visuospatial attention measured across visual cortex using source-imaged, steady-state EEG.

How does attention alter neural responses? Decades of electrophysiological measurements in non-human primates as well as human EEG and fMRI studies have shown that spatial attention modulates firing rates across the visual cortex, but the computations that drive this process are still unclear. Further, while it is well known that attention affects perception, we have only a limited understanding of the link between attentionally driven changes in neural firing rates and subject performance. Here we used a novel human neuroimaging method to measure the effect of spatial attention on neural responses in V1, hMT+, hV4, and the intraparietal sulcus (IPS). Attention altered signals in different ways across the visual cortex: areas V1, hMT+, and IPS exhibited primarily response gain changes while hV4 showed contrast gain modulation. Signals in V1, hMT+, and IPS correlated with contrast detection performance suggesting that behavior can be predicted by population-level signals as early as striate cortex.