Frontal β bursts segregate into rhythmically distinct regimes that differentiate cognitive states

Beta band rhythms often appear as brief bursts, but how variations in burst properties impact neural function is unclear. We probed beta burst heterogeneity by developing two complementary detection algorithms. One isolates brief high amplitude events (bursts of power, BoP) and another that identifies consistent oscillations that span multiple cycles (bursts of consistency, BoC). Examining frontal LFP and ECoG recordings from mice and macaques, these two burst types occupied the same 15 to 30 Hz frequency band yet showed minimal temporal overlap, indicating independent phenomena probably with distinct neural generators. Crucially, when task demands shifted between high and low cognitive control states, BoC bursts were enriched during demanding phases, whereas BoP bursts dominated routine phases. These results demonstrate that frontal beta activity comprises at least two rhythmically distinct regimes linked to different levels of cognitive control. Our dual mode framework refines mechanistic models of transient oscillations and underscores the significance of burst waveform diversity for flexible brain function.