Ocular Correction (Subspace projection-SSP, regression algorithm)

This approach has been commonly applied in the literature. SSP does not contrast artifacts and brain activity. Rather, the complete

subspace spanned by the artifact topographies is projected away from the recorded data. This leads to un-distorted data only in

the highly unlikely case when artifact and brain activity have exactly orthogonal topographies. This is generally not the case in real

data. In the likely event that evoked brain activity has a topography correlated with the artifact, this method removes the correlated

fraction of the brain activity. As one of the negative consequences, maps of the corrected brain activity will be severely distorted

after SSP correction.