Alpha-Band Oscillations Track Spatial Priority in the Human Brain

Spatial selection plays a central role in visual cognition, allowing us to prioritize processing at relevant locations. An emerging view is that alpha-band (8–12 Hz) oscillations play a key role in this core cognitive process. In this dissertation, I show that alpha-band oscillations track spatial priority with remarkable spatial and temporal resolution, and across a range of contexts. To this end, I develop an encoding model approach to reconstruct spatially selective response profiles (called channel-tuning functions, or CTFs) from alpha-band power measured with EEG. These alpha-band CTFs reflect the spatial selectivity of the population-level activity that is measured with EEG. In Chapter 2, I show that alpha activity precisely tracks the locus of attention, and that the time course of this activity tracks trial-by-trial variations in the latency of covert orienting, establishing it as a powerful means of tracking the temporal dynamics of covert spatial attention. In Chapter 3, I show that alpha activity precisely encodes spatial positions held in working memory, consistent with the broad hypothesis that there is considerable functional overlap between attention and working memory. In Chapter 4, I show that alpha activity tracks the spatial position of non-spatial memoranda held in working memory, even when space is wholly irrelevant to the task, suggesting that spatial attention is also recruited during the maintenance of non-spatial features in working memory. Finally, having established a tight link between alpha oscillations and spatial selection, in Chapter 5 I examine the consequences of spatial attention. Here, I show that spatial attention increases the amplitude of population-level representations of stimulus position. Together, these studies establish that alpha-band oscillations enable spatially and temporally resolved tracking of spatial attention, and highlights the central role that spatial attention plays in a range of cognitive contexts