Hi Doug et al,
from looking at the help on mris_surfglm it appears that vertices in the analyses are not as dense as those from the subject surfaces. I'm guessing that using the ico surface with 7 iterations of refinement (lots of vertices!), you then locate the nearest vertex in each subject for each ico vertex. So, the GLM analyses for any given ico vertex use data from different vertex numbers across subjects - are these vertex indices and ico vertex correspondence available as an output option or are they stored in a temp file or something? Say, for each vertex number of ico, a row vector of subject vertex indices, in the order they are input to mris_surfglm. Also, if the above assumption is correct, the implication may be that some slight variations in registration (alignment accuracy might vary to within 1 - 10 vertices, perhaps) could have an impact on the results? Is there any local vertex neighbourhood averaging of thickness values when extracting the individual subject values for the GLM? Cheers, Darren ----- Original Message ----- From: "Doug Greve" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Friday, October 11, 2002 2:13 AM Subject: Re: mris_surfglm > > Hi Darren, > > the ico and average7 are about the same computationally. However, it is > more convenient to use average7 it has a surface that you can directly > render the results on. With ico, you'd still have to run mri_surf2surf > to convert it to another surface. > > I'm not sure what you're trying to do in terms of the surface > registration... > > doug > > > Darren Weber wrote: > > > > Dear Doug et al, > > > > surfglm looks good. I have processed 10 controls and 8 patients such that > > each surface contains a whole cortical surface, without the usual split > > through the corpus callosum. How would I use the surface registration > > process? Should I use 'ico' as the average or can I use one of the > > subjects? > > > > Take care, Darren > > > > -- > > Darren Weber, PhD Student > > Cognitive Neuroscience, School of Psychology > > Flinders University of SA, GPO Box 2100, Adelaide, SA 5001, Aust. > > Ph: (61 8) 8201 3889, Fax: (61 8) 8201 3877 > > http://203.3.164.46/~dlw/homepages/index.html > > -- > Douglas N. Greve, Ph.D. > MGH-NMR Center > [EMAIL PROTECTED] > Phone Number: 617-724-2358 > Fax: 617-726-7422 >
