Modelling the Effects of Ongoing Alpha Activity on Visual Perception: The Oscillation-Based Probability of Response

Abstract

Substantial evidence has shown that ongoing neural activity significantly contributes to how the brain responds to upcoming stimuli. In visual perception, a considerable portion of trial-to-trial variability can be accounted for by prestimulus magneto/electroencephalographic (M/EEG) alpha oscillations, which play an inhibitory function by means of cross-frequency interactions with gamma-band oscillations. Despite the fundamental theories on the role of oscillations in perception and cognition, a clear theorization of the neural mechanisms underlying prestimulus activity effects that includes electrophysiological phenomena at different scales (e.g., local field potentials and macro-scale M/EEG) is still missing. Here, we present a model called the oscillation-based probability of response (OPR), which directly assesses the link between meso-scale neural mechanisms, macro-scale M/EEG, and behavioural outcome. The OPR model includes distinct meso-scale mechanisms through which alpha oscillations modulate M/EEG gamma activity, namely, by decreasing a) the amplitude and/or b) the degree of neural synchronization of gamma oscillations. Crucially, the OPR model makes specific predictions on the effects of these mechanisms on visual perception, as assessed through the psychometric function. SIGNIFICANCE STATEMENT The oscillation-based probability of response (OPR) is grounded on a psychophysical approach focusing on the psychometric function estimation and may be highly informative in the study of ongoing brain activity because it provides a tool for distinguishing different neural mechanisms of alpha-driven modulation of sensory processing.