POST-MOVEMENT EEG SYNCHRONIZATION STUDIED WITH DIFFERENT HIGH-RESOLUTION METHODS

In this paper we present a study of spline surface Laplacian (LP), lin ear estimation (LE) and analytical deblurring (AD) utilized to improve the spatial resolution of single trial EEG data. AD is a method to re construct the potential distribution on the cortical surface. The depe ndency of AD on the electrode grid size as well as the sensitivity to uncorrelated noise and errors in the volume conductor model are invest igated in detail and compared with LP. Finally, all methods (LP, LE an d AD) are applied to single trial EEG data recorded in three subjects during voluntary and self-paced extension and flexion movements of the right index finger. In each subject postmovement beta oscillations we re found in specific frequency bands. Cortical dipolar source strength s were reconstructed by LE and cortex potentials were estimated with A D. Both results are compared with LP calculated from the scalp EEG. Al l methods, although having different theoretical basis, yield similar results and reveal a maximal event-related synchronization over the le ft sensorimotor area approximately 500-875 ms after termination of the movement.