Can I use CSD data to compute an inverse solution with other source localization tools, such as BESA or LORETA?
CSD estimates represent underlying current generators because a surface Laplacian provides a conservative and accurate estimate of the current flow at the scalp. However, because the CSD transformation has already eliminated properties related to volume conduction, the use of CSD estimates as an input to “inverse” programs designed to infer, quantify and localize the intracranial generators of surface potentials (e.g., BESA, LORETA) is a violation of basic assumptions on which all of these inverse solution methods rely. Despite this caveat, it is still possible to expand the applicability of CSD methods by using inverse tools with surface potential topographies corresponding to time intervals or spectral bands (or their data-driven component simplications) that were initially identified and characterized using the reference-free CSD transform.
