Spatial Tuning of Alpha Oscillations in Human Visual Cortex

Neuronal oscillations at about 10 Hz, called alpha oscillations, are often thought to arise from synchronous activity across large regions of occipital cortex, reflecting general cognitive states such as attention, arousal, and alertness. However, there is also evidence that modulation of alpha oscillations in visual cortex can be spatially specific. Here, we used intracranial electrodes in human patients to measure alpha oscillations in multiple visual areas in response to visual stimuli whose location varied systematically across the visual field. We used a model-based approach to separate the alpha oscillation from broadband power changes. Using a population receptive field (pRF) model to explain the pattern of the alpha signal, we find that the alpha pRF centers are similar to those estimated from broadband (70–180 Hz) time series, but the sizes are several times larger. The results demonstrate that alpha suppression in human visual cortex can be precisely tuned. Finally, we show how the pattern of alpha responses can explain several features of exogenous visual attention. ### Competing Interest Statement The authors have declared no competing interest.