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Posted on 05/13/13 11:21:53
Number of posts: 9
Hi all,
I would like to run a seed PLS, and so have run a mean-centred PLS on my data. I obtained a cluster report using a BSR of +/-4 for the peak threshold, which I thought was pretty conservative. However, one of my most prominent peaks for my first LV occurs at a coordinate that seems to be smack dab in the middle of white matter (-21 -42 6). The cluster is 112 voxels, and seems to bleed into posterior hippocampus on the left, but nothing else aside from WM and ventricle. My data are re-sampled to a 3mm^3 voxel size.
1) Does it even make sense to use this cluster for a subsequent seed analysis?
2) If so, should I use the peak that occurs in the WM, or use an activated region that hits hippocampus.
Many thanks in advance
Replies:
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Posted on 05/30/13 13:13:42
Number of posts: 229
That is an interface between CSF and white matter, so I would check the data carefully before deciding to use this region as a seed.
I would first check your registrations and data quality against a T1-weighted image in the template space -
Following that, you can use the GUI's "voxel intensity response" option to make sure that the data are consistent across subjects
If you dont' see any indication that you have spurious data, you can use this cluster. In terms of which voxel(s) to use - it gets a bit trickier - the clustering algorithm finds contiguous voxels that meet your threshold, and the peak is simply the voxel with the strongest response. That does not preclude using your anatomical knowledge to further subdivide the cluster..
cheers
nancy
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