The spectral dynamics of visual awareness: An interplay of different frequencies?

Visual awareness involves a complex interplay of brain rhythms across different frequency bands. In an orientation discrimination task where response bias was induced, EEG recordings showed that alpha and beta bands are especially engaged when contrasting aware versus unaware trials, with a main power suppression for aware trials. Theta, alpha, beta, and gamma bands each contribute as prerequisites or post-perceptual processes, rather than a single frequency marking consciousness itself.

Study at a glance

Abstract

The goal of this study was to investigate the neurophysiological correlates of visual awareness, with a specific focus on its event-related spectral perturbation (ERSP) features. To this aim, we tried to disentangle the proper neural correlates of consciousness (NCC) from other prerequisite and post-perceptual processing. To do so, we administered an orientation discrimination task, inducing a response bias through task instructions. EEG results showed that different frequency bands are involved in this kind of task, with different spectral and temporal dynamics. In particular, alpha and beta bands seem to be particularly engaged, especially in the aware-unaware contrast, showing a main power suppression for aware trials and replicating previous literature. Moreover, we demonstrated that the process of visual awareness is orchestrated by a complex interaction of different frequencies (i.e., theta, alpha, beta and gamma) being involved as prerequisites and post-perceptual processes.