摘要：We describe a simple and efficient solution to the problem of reconstructing
electromagnetic sources into a canonical or standard anatomical space. Its simplicity rests
upon incorporating subject-specific anatomy into the forward model in a way that eschews
the need for cortical surface extraction. The forward model starts with a canonical cortical
mesh, defined in a standard stereotactic space. The mesh is warped, in a nonlinear fashion,
to match the subject's anatomy. This warping is the inverse of the transformation derived
from spatial normalization of the subject's structural MRI image, using fully automated
procedures that have been established for other imaging modalities. Electromagnetic lead
fields are computed using the warped mesh, in conjunction with a spherical head model (which
does not rely on individual anatomy). The ensuing forward model is inverted using an empirical
Bayesian scheme that we have described previously in several publications. Critically, because
anatomical information enters the forward model, there is no need to spatially normalize the
reconstructed source activity. In other words, each source, comprising the mesh, has
a predetermined and unique anatomical attribution within standard stereotactic space.
This enables the pooling of data from multiple subjects and the reporting of results in
stereotactic coordinates. Furthermore, it allows the graceful fusion of fMRI and MEG data
within the same anatomical framework.
