Individual anatomy of the
brain and especially the folding of the neocortical sheet can differ quite dramatically
from person to person. We try to respect the underlying anatomy by analyzing
the functional data using surface-based methods. A high-resolution
T1-weighted (anatomical) scan is used to generate a segmentation between
cortical white and gray matter. The boundary between the two is then
reconstructed to form an accurate 3D-model of the individual cortical
surface. This surface then can be blown up and aligned with other
participants based on cortical or functional landmarks. On the left we have
an image of the flattened left cerebral hemisphere and flattened
We use the software
package SureFit and Caret,
written and freely distributed by David van Essen's lab at Washington University.
For anatomically well defined functional areas, such as primary motor cortex,
this method leads to much more accurate alignment than 3D-morphing, which is
often used for fMRI studies.