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.