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.