Terry,
On Feb 9, 2006, at 11:37 AM, Terry Sewards wrote:
.... In their description of the cytoarchitectonic map of area 2
Grefkes et al. (2001) show area 2 occupying the rostral bank of the
postcentral sulcus, not extending into the fundus or caudal bank,
but in the
probabilistic maps area 2 appears to occupy - in addition to the
rostral
bank - a large sector of the fundus and caudal bank. Is this
entirely due
to the fact that the location of the postcentral sulcus is variable in
individual human subjects?
YES. This spread is evident in their own representations (their Fig.
7) and in our PALS maps, whether you look in the volume or the surface.
(but if this were the case, then a probabilistic
map of area AIP would presumably overlap considerably with the area
2 map).
Yes indeed. While we don't have data for AIP to confirm the point,
we do have it for their area 1, which overlaps extensively with area
2. Ditto for many other pairs of adjacent architectonic areas (e.g.,
areas 44 and 45 illustrated in the PALS paper).
IF surface reconstructions were available to reconstruct the
individual hemispheres for these particular cases, then it would be
possible to use surface-based registration to align the individuals
to the PALS atlas. I can pretty much guarantee you in that case that
there would be much less spread of a surface-based probabilistic area
2 into the fundus and caudal bank of the PoCes. However, the MRI's
from these individuals were not good enough to get good surface
reconstructions, so for the time being we have to live with the
greater variability imposed by volume-based registration when making
use of the excellent Zilles-lab architectonic maps.
David
