computing an RMS current density estimate for {TAIL ~ each voxel} from the covariance matrix and {HEAD ~ the forward solution} for that voxel; and 
computing an RMS current density estimate for { TAIL ~ each voxel } from the covariance matrix and { HEAD ~ the forward solution } for that voxel ; and
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH