The power change of electroencephalographic (EEG) rhythms is an indicator to investigate neuronal activation underlying EEG electrodes. We developed a software routine for analysis and visualization of spatiotemporal patterns of EEG oscillations: event-related desynchronization (ERD) and event-related synchronization (ERS). Further, the spatiotemporal representation of task-related coherence (TRC) was also proposed for investigation of interregional neuronal connectivity. As concurrent artifacts and volume conduction effect may result incorrect or spatially blurred estimation of EEG features, we have embedded data preprocessing functions to reduce these effects including: correcting eye movement-related artifact, changing reference methods and spatial filtering undesirable neuronal activity. These functions were subsequently applied to study EEG time-frequency patterns during self-paced movements in normal volunteers.