Resting Cortical Alpha and Beta Oscillations are Continuous Across Space and Frequency

Cortical alpha and beta oscillations are traditionally conceptualized as spatially distinct, with alpha rhythms constrained to the occipital cortex and beta rhythms to frontal cortices. Little work has tested this spatial separability empirically and explored whether the distribution of these cortical rhythms may be continuous in space and frequency. Using task-free magnetoencephalography of 604 participants and density-based unsupervised clustering of individual spatio-spectral peaks, we show that the distribution of cortical oscillatory activity across the alpha-to-beta frequency range is structured along a continuous spatio-spectral gradient from occipitotemporal to frontal cortices. Across individuals, the expression of this gradient correlates positively with cognition and decays with age. This work introduces a continuous spatio-spectral organizational structure linking alpha- and beta-band activity across all lobes of the neocortex, with a potential role in flexible segregation and integration of communication between sensorimotor regions of the brain.