Colin 27 Average Brain
		    Stereotaxic Registration Model


This is a stereotaxic average of 27 T1-weighted MRI scans of the same
individual.  This average dataset was created in a two step process.
First, each of the 27 T1-weighted scans were registered to stereotaxic
space using the mritotal procedure and resampled onto a 1mm grid in
stereotaxicc space.  All 27 scans were averaged together to create an
initial average.  This average volume was used as a target for the
second phase of registration where each original T1-weighted MRI was
re-registered in stereotaxic space.  This procedure has the advantage
of removing the small variance in intra-subject mapping in stereotaxic
space associated with the use of a multi-subject average.  This
procedure has been described in detail in:

   Holmes CJ, Hoge R, Collins L, Woods R, Toga AW, Evans AC.
   "Enhancement of MR images using registration for signal averaging."
   J Comput Assist Tomogr. 1998 Mar-Apr;22(2):324-33.

The volumes here are specially adapted for use with the MNI Linear
Registration Package (mni_autoreg).  Included in this package are the
following files:

     colin27_t1_tal_lin.mnc:
	a version of the average of 27 scans described above. This
        volume covers the whole brain (unlike the original Talairach
        atlas), and is sampled with 1mm cubic voxels
     colin27_t1_tal_lin_mask.mnc, colin27_t1_tal_lin_mask.obj:
	a mask of the intra-cranial cavity of colin27.mnc, created
        using mincbet-1.3.6 (derived from FSL Bet)
     colin27_t1_tal_lin_headmask.mnc:
	a rough mask of the whole head, required for nonlinear mode
     colin27_t1_tal_lin_vent.mnc, colin27_t1_tal_lin_vent.obj:
        a mask of the ventricles
     colin_t1_tal_lin_ntags_1000_bg.tag:
        tag points for the background for colin27_t1_tal_lin.mnc
     colin_t1_tal_lin_ntags_1000_nobg.tag:
        tag points for the CSF, GM, and WM for colin27_t1_tal_lin.mnc
     Cerebellum_Ventricles_SubCortical_Mask-colin.mnc:
        a template for the cerebellum, brain-stem, ventricles and sub-cortical
        gray to be used in the CIVET pipeline
     colin_to_icbm152_2009a.xfm, colin_to_icbm152_2009a_grid_0.mnc:
        a non-linear transform to map the Colin model to the MNI-ICBM152-2009a
        model.