I know that the grey or white matter volume measures for the ROIs reported in "wmparc.mgz" can be adjusted for the total intracranial volume.... Is is correct to do the same for surfaces? I mean can the surface of an ROI (e.g. precentral) be adjusted to total surface area? If yes, this must be done for total white right or total left depending on the ROI if it is left or right, correct?