Quantification of movement-related modulation on beta activity of single-trial magnetoencephalographic measurement using independent component analysis (ICA)

An ICA-based method is proposed to quantify the single-trial response of beta-band activities of sensorimotor rhythm in the right index finger lifting task. The magnetic fields of four right-handed subjects (2 males and 2 females) were recorded by a whole-head magnetoencephalography. ICA was applied to separate each rhythmic epoch into temporally independent components by means of an un-mixing matrix. According to the temporal and spatial characteristics of the decomposed components, task-related ones are selected for data reconstruction. Compared with the conventional Amplitude Modulation (AM) method with 100 averaged trials, the ICA-based method not only preserved the trial-by-trial variabilities of rhythmic activities, but also significantly improves the decreased amplitudes in event-related desynchronization (ERD) and the rebounds in event-related synchronization (ERS).