The relationship between neural variability and neural oscillations

Neural activity fluctuates over time, creating considerable variability across trials. This trial-by-trial neural variability is dramatically reduced (“quenched”) after the presentation of sensory stimuli. Likewise, the power of neural oscillations, primarily in the alpha-beta band, is also reduced. Despite their similarity, these phenomena have been discussed independently. We hypothesized that the two phenomena are tightly coupled. To test this, we examined magnetoencephalography (MEG) recordings of healthy subjects viewing repeated presentations of a visual stimulus. The timing, amplitude, and spatial topography of variability-quenching and power suppression were remarkably similar. Neural variability quenching was eliminated by excluding the alpha-beta band from the recordings, but not by excluding other frequency-bands. Moreover, individual magnitudes of alpha-beta band power explained 86% of between-subject differences in variability quenching. In contrast, inter-trial-phase-coherence (ITPC) was not correlated with variability quenching. These results reveal that neural variability quenching reflects stimulus-induced changes in the power of alpha-beta band oscillations.