Fast and slow oscillations in human primary motor cortex predict oncoming behaviorally relevant cues.

Beta oscillations (12-30 Hz) in local field potentials are prevalent in the motor system, yet their functional role within the context of planning a movement is still debated. In this study, a human participant implanted with a multielectrode array in the hand area of primary motor cortex (MI) was instructed to plan a movement using either the second or fourth of five sequentially presented instruction cues. The beta amplitude increased from the start of the trial until the informative (second or fourth) cue, and was diminished afterwards. Moreover, the beta amplitude peaked just prior to each instruction cue and the delta frequency (0.5-1.5 Hz) entrained to the interval between the cues-but only until the informative cue. This result suggests that the beta amplitude and delta phase in MI reflect the subject's engagement with the rhythmically presented cues and work together to enhance sensitivity to predictable and task-relevant visual cues.