Visual modulation of resting state alpha oscillations

Abstract

Once thought to simply reflect passive cortical idling, recent studies have demonstrated that alpha oscillations play a causal role in cognition and perception. However, whether and how cognitive or sensory processes modulate various components of the alpha rhythm is poorly understood. Sensory input and resting states were manipulated in human subjects while electroencephalography (EEG) activity was recorded in three conditions: eyes-open fixating on a visual stimulus, eyes-open without visual input (darkness), and eyes-closed without visual input (darkness). We show that alpha power and peak frequency increase when visual input is reduced compared to the eyes open, fixating conditions. These results suggest that increases in alpha power reflect a shift from an exteroceptive to interoceptive state and that increases in peak frequency following restricted visual input (darkness) may reflect increased sampling of the external environment in order to detect stimuli. They further demonstrate how sensory information modulates alpha and the importance of selecting an appropriate resting condition in studies of alpha.

Significance Statement Alpha oscillations have long been considered to reflect a stable neural trait, but we demonstrate that alpha is a state that varies with sensory input. By manipulating both eye state and sensory input, we demonstrate that under resting state conditions, visual input drives changes in alpha power and peak frequency. These changes likely allow the visual system to dynamically switch between interoceptive and exteroceptive states to prioritize detection of weak and/or infrequent visual stimuli. This work has important implications for studies of resting state brain dynamics, which have traditionally employed a variety of resting state conditions that may or may not match task conditions in terms of sensory input.