Brain dynamics in alpha and beta frequencies underlies response activation during readiness of goal-directed hand movement

Abstract

How the brain generates response readiness and preparation for hand movements is not yet understood. We hypothesised that coupled interactions in alpha and beta frequencies become modulated in central-motor brain areas during response readiness. Phase synchronization in alpha (~9–11 Hz) and beta (~18–22 Hz) frequencies was analysed prior to a finger response in people with normal lateralised readiness potentials (LRP). Specifically, Phase Locking Values (PLV) and source topographies were assessed in EEG data with Go-NoGo tasks in 18 healthy participants. Analyses involving alpha and beta phase-coupled activity in electrodes overlying central-motor brain regions and from adjacent frontal sites were compared to address the hypothesised specificity of motor area modulations as underlying response readiness. Control analyses using alpha-beta phase-coupling with the alpha at electrodes overlying occipital areas were included. Results revealed smaller PLVs in the alpha-beta phase interactions using alpha from C3, Cz, C4 electrodes compared with alpha from F3, Fz, F4, thereby isolating motor regions specifically. Analyses of the source topography of synchronous beta signals (coupled with central-motor alpha) revealed parietal, occipital and right frontal areas, possibly implicating a role of motor and visual attention, movement intention in the time window of the LRP. In sum, we isolated central-motor interactions involving centrally located alpha, coupled with parietal, occipital, and frontal beta activity in association with processes of movement readiness.