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Yes, the question of "trackability" is actually the motivation to write out and normalize to the waytotal based on a discussion I had with Tim. The idea was that this may vary for biological (e.g. perifocal edema around a tumor) and / or physical reasons, and that from a Bayesian perpective it makes sende to normalize to the waytotal if you know that a tract exists (e.g. the pyramidal tract if the person has no hemiplegia). According to my experience, the waytotal may still vary across heimspheres and subjects by a factor of 2 up to 5 for a given tract even when there is no obvious biological (such as edema) or physical (such as noise) reason why you would expect that. However, the waytotal drops significantly when there is perifocal edema around a lesion and also when you increase the noise by using parallel imaging, for example. When it drops to less than 20% compared to the contralateral side you can almost invariably expect the patient to be exhibit functional impairments realted to the tract, such as a drop in motor / muscle strength for the pyramidal tract. At least on our scanner / coil / setup, and that's why I believe it is quite useful (i.e. to some extent even across hemispheres and subjects). However, per se that normalization does not change the spatial extent of the fdt_path output and it remains arbitrary at what level you may want to threshold the tract (if you want to at all). Cheers- Andreas ________________________________ Von: FSL - FMRIB's Software Library im Auftrag von Matt Glasser Gesendet: Fr 05.12.2008 04:07 An: [log in to unmask] Betreff: Re: [FSL] question on old and new waytotals My understanding is that dividing by the waytotal is the way to normalize across subjects as best as you can. Then you could threshold at some fractional proportion of the waytotal and binarize. This should give you the most similar spatial distributions across subjects. However, I think that this method is less useful when you are making comparisons within a brain, for example between the same pathway in the two hemispheres, when you are interested in pathway asymmetries for example. Peace, Matt. -----Original Message----- From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On Behalf Of David Gutman Sent: Thursday, December 04, 2008 8:46 PM To: [log in to unmask] Subject: Re: [FSL] question on old and new waytotals I'v talked with Matt about this issue in the past. Other than controlling for the volum of the seed you use (which since I run most things in a standard space isn't an issu) just dividing by the total # of threads, which should be the same across subjects, would just scale the images, but not actually "normalize" between subjects. Generally it seems the "trackability" really does significantly vary between subjects. The variance between subjects is very unlikely due to some real biological difference, since the variance is sometimes on the order of 1-2 magnitudes between subjects, in terms of the "raw" number of fibers that may make it from seedmask A to targets B and C. I'll see numbers vary from the 100's in subject 1 to the thousands or even 10s of thousands between subjects.... Ive played around in the past, as I said, with some internal standard "non" interesting tract but was never super happy with the results. Maybe Tim/Saad/Steve or some of the more physics minded people have some thoughts about this-- in particular maybe looking at the variance in one of the FA derived metrics (and I won't pretend to fathom which one) that could be used as some sort of pseudo-objective standard of DTI image quality across some large/homogenous region of cortex (if such a thing exists....) DG On Thu, Dec 4, 2008 at 8:42 PM, Cherif Sahyoun <[log in to unmask]> wrote: > Hi David, > > I like the internal standard idea. As you pointed it is hard to > implement/justify though. > Perhaps something based on the eigenvalues could be used to quantify >Oo the "trackability" of each subject... > > The percentage idea is basically what I had in mind when talking about > dividing by the max (or 98th percentile), but see also Matt's > concerns. > > Thanks, > Cherif > > > On Thu, Dec 4, 2008 at 8:08 PM, David Gutman <[log in to unmask]> wrote: >> Cherif I have noted similar absolute number differences between >> subjects, like a scaling difference, where the tracts themselves look >> extremely similar. My current thoughts are that the "trackability" of >> an image varies significantly from subject to subject depending on >> things like you mentioned, scan quality, motion, etc... >> >> >> One thing I was thinking of, almost analogous to other methodologies >> (like when you try and amplify DNA/RNA you may choose a gene that >> "shouldn't be different" to serve as a loading control and use that to >> scale all of your values... myosin or actin or other messenger genes >> are often used in this sort of analysis, and the relative >> mRNA/whatever expression is correlated using some sort of internal >> standard.... >> >> For DTI, I am unaware of any "internal standard"/tract that could be >> used for comparison, and have played around with this in the past >> (although it's been a while). I'd really like to get other people's >> feedback on this concept; in particular it would be nice to pick a >> relatively uninteresting region (or combination of regions) where you >> say calculate the number of fibers along the optic radiations, or >> maybe part of the corpus collosum and for every subject tract the >> number of fibers that make it from A to B and then use this reference >> tract to scale all of your more "interesting" tracts.... so basically >> pick a region that you think should not change between >> people/subjects/whatever... >> >> Also just looking at relative percentages instead of absolute numbers >> may get around this sort of issue of just looking at raw numbers which >> is often what I wind up doing (although this also can have its >> pitfalls). >> >> >> DG >> >> >> >> >> >> It's been an issue I've been thinking about for quite some time, but I >> >> On Thu, Dec 4, 2008 at 7:49 PM, Cherif Sahyoun <[log in to unmask]> wrote: >>> Oh of course! Sorry, I should not email at 2 AM, uncaffeinated! >>> >>> The reason I wanted to use something based on the pathway itself is >>> because of the wide variability in numbers between subjects. There are >>> different ranges of values between subjects, which cannot be explained >>> by the size of the ROI, making comparison difficult. This may be due >>> to the quality of the scans, slightly more motion, etc. but the tracts >>> still look great, so I really think they are normal subject-specific >>> variance and not a "problem" per se. >>> With that in mind, waytotal normalization made most sense to me, but >>> now I'm a bit stuck with many tracts already run, hence the new >>> suggestions... >>> >>> Best, >>> Cherif. >>> >>> ---------------------------------------------------------------------------- -------------- >>> Cherif P. Sahyoun HST-MEMP >>> >>> Developmental Neuroimaging of Cognitive Functions >>> >>> C: 617 688 8048 >>> H: 617 424 6956 >>> [log in to unmask] >>> >>> "Live as if this were your last day. Learn as if you'll live forever" >>> Gandhi >>> ---------------------------------------------------------------------------- --------------- >>> >>> >>> >>> On Thu, Dec 4, 2008 at 9:52 AM, Matt Glasser <[log in to unmask]> wrote: >>>> You could also normalize/threshold according to the total number of samples >>>> sent out (# voxels in seed ROIs X # of samples sent out from each voxel). I >>>> don't think you want to normalize based on something that is dependant on >>>> the spatial distribution of the pathway, which the 98th percentile will >>>> still be. >>>> >>>> Peace, >>>> >>>> Matt. >>>> >>>> -----Original Message----- >>>> From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On Behalf >>>> Of Cherif Sahyoun >>>> Sent: Thursday, December 04, 2008 12:55 AM >>>> To: [log in to unmask] >>>> Subject: Re: [FSL] question on old and new waytotals >>>> >>>> Hey Matt, >>>> >>>> Thanks for the quick reply. What do you mean by "two" good options? >>>> the first is re-running probtrackx and getting waytotal out. What's >>>> the second? >>>> I thought the 98th percentile might get around (to some extent) the >>>> max issue, since we're less sensitive to the size of the core. >>>> >>>> Thanks, >>>> Cherif >>>> >>>> ---------------------------------------------------------------------------- >>>> -------------- >>>> Cherif P. Sahyoun HST-MEMP >>>> >>>> Developmental Neuroimaging of Cognitive Functions >>>> >>>> C: 617 688 8048 >>>> H: 617 424 6956 >>>> [log in to unmask] >>>> >>>> "Live as if this were your last day. Learn as if you'll live forever" >>>> Gandhi >>>> ---------------------------------------------------------------------------- >>>> --------------- >>>> >>>> >>>> >>>> On Wed, Dec 3, 2008 at 9:41 PM, Matt Glasser <[log in to unmask]> wrote: >>>>> I don't think that is a good idea for the same reason I stated for the >>>> max. >>>>> Now that the waytotal bug has been fixed, you have two good options. The >>>>> waytotal measures more accurately what you are trying to get at via using >>>>> the max or the 98th percentile. >>>>> >>>>> Peace, >>>>> >>>>> Matt. >>>>> >>>>> -----Original Message----- >>>>> From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On Behalf >>>>> Of Cherif Sahyoun >>>>> Sent: Wednesday, December 03, 2008 6:37 PM >>>>> To: [log in to unmask] >>>>> Subject: Re: [FSL] question on old and new waytotals >>>>> >>>>> Hey Saad, Matt, and the Gang, >>>>> >>>>> Does anyone has thoughts on using the upper output of fslstats -r as a >>>>> normalizing factor? >>>>> >>>>> Thanks, >>>>> Cherif. >>>>> >>>>> >>>> ---------------------------------------------------------------------------- >>>>> -------------- >>>>> Cherif P. Sahyoun HST-MEMP >>>>> >>>>> Developmental Neuroimaging of Cognitive Functions >>>>> >>>>> C: 617 688 8048 >>>>> H: 617 424 6956 >>>>> [log in to unmask] >>>>> >>>>> "Live as if this were your last day. Learn as if you'll live forever" >>>>> Gandhi >>>>> >>>> ---------------------------------------------------------------------------- >>>>> --------------- >>>>> >>>>> >>>>> >>>>> On Wed, Dec 3, 2008 at 1:47 PM, Saad Jbabdi <[log in to unmask]> wrote: >>>>>> No, waytotal is independent of seed_to_target. >>>>>> maybe the confusion comes from the fact that your are talking about >>>>>> seed_to_target, but what you mean is setting waypoints and exclusion >>>>> masks. >>>>>> seed_to_target (at least for us) refers to the classification targets (as >>>>>> the output of such analysis are called seed_to_<target>). >>>>>> so here is a summary of what happens (hopefully to avoid confusion, >>>> rather >>>>>> than add to it!); >>>>>> . waytotal counts the number of non-rejected tracts. >>>>>> . if waypoint masks or exclusion masks are used, then waytotal should go >>>>>> down (or eventually doesn't change) >>>>>> . if waypoint masks or exclusion masks are NOT used, then waytotal should >>>>> be >>>>>> equal to the total number of requested samples (i.e. no sample has been >>>>>> rejected) >>>>>> . setting classification targets (seed_to_target) does NOT affect >>>>> waytotal. >>>>>> . the values calculated in seed_to_target are not affected by the recent >>>>>> patch (FSL4.1.2), since their values were NOT underestimated. >>>>>> I hope this was clear? >>>>>> Cheers, >>>>>> Saad. >>>>>> >>>>>> On 3 Dec 2008, at 18:12, Markus Gschwind wrote: >>>>>> >>>>>> Saad, >>>>>> just one other thing: >>>>>> >>>>>> It is only the Seed_to_target-waytotal which is wrong, not the seed >>>>>> (alone)-waytotal, right? >>>>>> >>>>>> Thanks, Markus >>>>>> >>>>>> >>>>>> 2008/12/3 Markus Gschwind <[log in to unmask]> >>>>>>> >>>>>>> Hi Saad! >>>>>>> That is fantastic news! >>>>>>> I am curious if it changes my waytotals! >>>>>>> Thanks for your high presence here in the list! >>>>>>> Markus >>>>>>> >>>>>>> >>>>>>> 2008/12/3 Saad Jbabdi <[log in to unmask]> >>>>>>>> >>>>>>>> >>>>>>>> Hello Saad! >>>>>>>> >>>>>>>>> ...so I would be surprised if there were 50 articles published that >>>> are >>>>>>>>> using it! >>>>>>>> >>>>>>>> Sorry. I was just guessing out of my guts... I overestimated the >>>>>>>> importance of probtrackx ;-) >>>>>>>> >>>>>>>> I was actually referring to waytotal. I'm sure there are many papers >>>>>>>> using probtrack(x) :-) >>>>>>>> >>>>>>>> >>>>>>>> Can the patch also be installed to FSL 4.0.4? >>>>>>>> >>>>>>>> You can use the probtrackx binary (copy it into $FSLDIR/bin), but you >>>>>>>> can't mix the source files if you need your own build... >>>>>>>> >>>>>>>> Cheers, >>>>>>>> Saad. >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> Thank you for your support! >>>>>>>> Markus >>>>>>>> >>>>>>>> >>>>>>>> 2008/12/1 Cherif Sahyoun <[log in to unmask]> >>>>>>>>> >>>>>>>>> I see, so this will be too dependent on how much overlap there is at >>>>> the >>>>>>>>> core... >>>>>>>>> Any other possibilities? maybe using a percentile? (upper output of >>>>>>>>> fslstats -r)? >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>> >>>> ---------------------------------------------------------------------------- >>>>> -------------- >>>>>>>>> Cherif P. Sahyoun >>>>> HST-MEMP >>>>>>>>> >>>>>>>>> Developmental Neuroimaging of Cognitive Functions >>>>>>>>> >>>>>>>>> C: 617 688 8048 >>>>>>>>> H: 617 424 6956 >>>>>>>>> [log in to unmask] >>>>>>>>> >>>>>>>>> "Live as if this were your last day. Learn as if you'll live forever" >>>>>>>>> Gandhi >>>>>>>>> >>>>>>>>> >>>>> >>>> ---------------------------------------------------------------------------- >>>>> --------------- >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> On Mon, Dec 1, 2008 at 5:41 PM, Matt Glasser <[log in to unmask]> wrote: >>>>>>>>> > I don't think using the max value of the fdt_paths is a good idea. >>>>>>>>> > That >>>>>>>>> > will vary depending on how closely packed the samples are at the >>>>>>>>> > narrowest >>>>>>>>> > point of the tract. For example if you have a 100000 sample pathway >>>>>>>>> > that at >>>>>>>>> > its narrowest point goes through a single voxel, that voxel's value >>>>>>>>> > would be >>>>>>>>> > 100000, and that would be the max of the fdt_paths. If you had a >>>>>>>>> > separate >>>>>>>>> > 100000 sample pathway that at its narrowest point was divided evenly >>>>>>>>> > among 4 >>>>>>>>> > voxels, the maximum value of the fdt_paths would be 25000. >>>>>>>>> > Normalizing >>>>>>>>> > based on this number would give you very different probability >>>> values >>>>>>>>> > across >>>>>>>>> > the entire pathway, even if the two were otherwise identical. >>>>>>>>> > >>>>>>>>> > Peace, >>>>>>>>> > >>>>>>>>> > Matt. >>>>>>>>> > >>>>>>>>> > -----Original Message----- >>>>>>>>> > From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On >>>>>>>>> > Behalf >>>>>>>>> > Of Cherif Sahyoun >>>>>>>>> > Sent: Monday, December 01, 2008 4:10 PM >>>>>>>>> > To: [log in to unmask] >>>>>>>>> > Subject: Re: [FSL] question on old and new waytotals >>>>>>>>> > >>>>>>>>> > Hi Saad, >>>>>>>>> > >>>>>>>>> > Can you talk about the implications of using something other than >>>> the >>>>>>>>> > waytotal for normalizing? I'll get you started :) >>>>>>>>> > >>>>>>>>> > - using waytotal would give the conditional probability of going >>>>>>>>> > through a given voxel, given that there is a path. >>>>>>>>> > - using the ROI_size*samples would give the absolute probability of >>>>>>>>> > going through a voxel (on the path) >>>>>>>>> > What to you think of using the max value of the fdt_paths? That >>>>> should >>>>>>>>> > give a normalized conditional probability similar to using waytotal >>>>>>>>> > (though obviously we important differences since now we are forcing >>>>>>>>> > the most likely voxels to have a probability of 1, which was not the >>>>>>>>> > case using waytotal)... >>>>>>>>> > If what one wants is just to normalize across subjects to be able to >>>>>>>>> > compare mean p of a tract, I guess that would work? >>>>>>>>> > >>>>>>>>> > Best, >>>>>>>>> > Cherif >>>>>>>>> > >>>>>>>>> > >>>>>>>>> > >>>>> >>>> ---------------------------------------------------------------------------- >>>>>>>>> > -------------- >>>>>>>>> > Cherif P. Sahyoun >>>>>>>>> > HST-MEMP >>>>>>>>> > >>>>>>>>> > Developmental Neuroimaging of Cognitive Functions >>>>>>>>> > >>>>>>>>> > C: 617 688 8048 >>>>>>>>> > H: 617 424 6956 >>>>>>>>> > [log in to unmask] >>>>>>>>> > >>>>>>>>> > "Live as if this were your last day. Learn as if you'll live >>>> forever" >>>>>>>>> > Gandhi >>>>>>>>> > >>>>>>>>> > >>>>> >>>> ---------------------------------------------------------------------------- >>>>>>>>> > --------------- >>>>>>>>> > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> > On Mon, Dec 1, 2008 at 4:54 PM, Saad Jbabdi <[log in to unmask]> >>>>>>>>> > wrote: >>>>>>>>> >> Hi Markus, >>>>>>>>> >> When you say 50 papers, you must be thinking of the seed_to_target >>>>>>>>> >> values, >>>>>>>>> >> not waytotal, am I right? The output of seed_to_target is NOT >>>>>>>>> >> underestimated, it is only waytotal. >>>>>>>>> >> the waytotal file is a recent output in probtrackx, so I would be >>>>>>>>> > surprised >>>>>>>>> >> if there were 50 articles published that are using it! >>>>>>>>> >> To answer your question, I think it is quite hard to predict the >>>>>>>>> >> behaviour >>>>>>>>> >> of waytotal as it is now, so I would recommend re-running your >>>>>>>>> >> analysis >>>>>>>>> > with >>>>>>>>> >> the patch to come if you are planning to use waytotal. >>>>>>>>> >> Cheers, >>>>>>>>> >> Saad. >>>>>>>>> >> >>>>>>>>> >> On 1 Dec 2008, at 17:20, Markus Gschwind wrote: >>>>>>>>> >> >>>>>>>>> >> That is very good news! Thank you so much! >>>>>>>>> >> >>>>>>>>> >> However, I am really curious if there is an officially recommended >>>>>>>>> >> way of >>>>>>>>> >> dealing with this underestimation. Roughly guessed, there are about >>>>>>>>> >> 50 >>>>>>>>> >> publications using those "old" waytotals and if I contribute >>>> another >>>>>>>>> >> one, >>>>>>>>> >> now that it is known that those values are not always true... >>>>>>>>> >> Should all the people who are still working with FSL 4.0.x really >>>>>>>>> >> restart >>>>>>>>> >> the whole analyis in FSL 4.1? >>>>>>>>> >> >>>>>>>>> >> Would there be another way? >>>>>>>>> >> >>>>>>>>> >> Many regards, >>>>>>>>> >> Markus >>>>>>>>> >> >>>>>>>>> >> >>>>>>>>> >> >>>>>>>>> >> >>>>>>>>> >> >>>>>>>>> >> 2008/12/1 Saad Jbabdi <[log in to unmask]> >>>>>>>>> >>> >>>>>>>>> >>> Hi All, >>>>>>>>> >>> >>>>>>>>> >>> The patch -should be- available tomorrow :-) >>>>>>>>> >>> >>>>>>>>> >>> Thank you all for pointing this out! >>>>>>>>> >>> >>>>>>>>> >>> Cheers, >>>>>>>>> >>> Saad. >>>>>>>>> >>> >>>>>>>>> >>> >>>>>>>>> >>> On 28 Nov 2008, at 20:23, Martin Kavec wrote: >>>>>>>>> >>> >>>>>>>>> >>>> Thanks a lot Saad, >>>>>>>>> >>>> >>>>>>>>> >>>> at least we helped to point out the problem. Could you please let >>>>>>>>> >>>> us >>>>>>>>> >>>> know, >>>>>>>>> >>>> when we could expect the patch? >>>>>>>>> >>>> >>>>>>>>> >>>> Thanks, >>>>>>>>> >>>> >>>>>>>>> >>>> Martin >>>>>>>>> >>>> >>>>>>>>> >>>> On Friday 28 November 2008 19:50:43 Saad Jbabdi wrote: >>>>>>>>> >>>>> >>>>>>>>> >>>>> Hi Markus (and Yan Liu), >>>>>>>>> >>>>> >>>>>>>>> >>>>> I am terribly sorry, but just realised that I haven't included >>>>>>>>> >>>>> that >>>>>>>>> >>>>> fix to the released FSL!!! You will need to wait for the next >>>>>>>>> >>>>> patch >>>>>>>>> >>>>> now... >>>>>>>>> >>>>> >>>>>>>>> >>>>> And to answer your question, in principle it should >>>> underestimate >>>>>>>>> >>>>> waytotal by 50% on average if you set the option "--randfib". >>>>>>>>> >>>>> Otherwise it is difficult to predict by how much it will >>>>>>>>> >>>>> underestimate >>>>>>>>> >>>>> it for each data set.. >>>>>>>>> >>>>> >>>>>>>>> >>>>> Again, I am sorry for any inconvenience. >>>>>>>>> >>>>> >>>>>>>>> >>>>> Cheers, >>>>>>>>> >>>>> Saad. >>>>>>>>> >>>> >>>>>>>>> >>>> >>>>>>>>> >>>> -- >>>>>>>>> >>>> ********************************** >>>>>>>>> >>>> Senior Clinical Research Associate >>>>>>>>> >>>> MRI Unit of the Department of Radiology >>>>>>>>> >>>> Erasme Hospital >>>>>>>>> >>>> Lennik Street 808 >>>>>>>>> >>>> B-1070 Brussels >>>>>>>>> >>>> BELGIUM >>>>>>>>> >>>> >>>>>>>>> >>>> tel: +32-2-555-4325 >>>>>>>>> >>>> fax: +32-2-555-3994 >>>>>>>>> >>>> email: [log in to unmask] >>>>>>>>> >>>> ********************************** >>>>>>>>> >>>> >>>>>>>>> >>>> ----------------------------------------------- >>>>>>>>> >>>> Find a way, or make one! >>>>>>>>> >>>> >>>>>>>>> >>> >>>>>>>>> >>> Saad Jbabdi >>>>>>>>> >>> Oxford University FMRIB Centre >>>>>>>>> >>> >>>>>>>>> >>> JR Hospital, Headington, OX3 9DU, UK >>>>>>>>> >>> +44 (0) 1865 222545 (fax 717) >>>>>>>>> >>> www.fmrib.ox.ac.uk/~saad >>>>>>>>> >> >>>>>>>>> >> >>>>>>>>> >> >>>>>>>>> >> -- >>>>>>>>> >> Dr. med. Markus Gschwind, M.D. >>>>>>>>> >> Laboratory for Neurology and Imaging of Cognition >>>>>>>>> >> Dept of Neurosciences >>>>>>>>> >> University Medical Center (CMU) >>>>>>>>> >> 1 Michel-Servet - 1211 GENEVA - CH >>>>>>>>> >> >>>>>>>>> >> Tel 0041 (0) 22 379 5324 >>>>>>>>> >> Fax 0041 (0) 22 379 5402 >>>>>>>>> >> email: [log in to unmask] >>>>>>>>> >> http://labnic.unige.ch <http://labnic.unige.ch/> >>>>>>>>> >> >>>>>>>>> >> Saad Jbabdi >>>>>>>>> >> Oxford University FMRIB Centre >>>>>>>>> >> JR Hospital, Headington, OX3 9DU, UK >>>>>>>>> >> +44 (0) 1865 222545 (fax 717) >>>>>>>>> >> www.fmrib.ox.ac.uk/~saad >>>>>>>>> >> >>>>>>>>> >> >>>>>>>>> >> >>>>>>>>> >> >>>>>>>>> >> >>>>>>>>> >> >>>>>>>>> > >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> -- >>>>>>>> Dr. med. Markus Gschwind, M.D. >>>>>>>> Laboratory for Neurology and Imaging of Cognition >>>>>>>> Dept of Neurosciences >>>>>>>> University Medical Center (CMU) >>>>>>>> 1 Michel-Servet - 1211 GENEVA - CH >>>>>>>> >>>>>>>> Tel 0041 (0) 22 379 5324 >>>>>>>> Fax 0041 (0) 22 379 5402 >>>>>>>> email: [log in to unmask] >>>>>>>> http://labnic.unige.ch <http://labnic.unige.ch/> >>>>>>>> >>>>>>>> Saad Jbabdi >>>>>>>> Oxford University FMRIB Centre >>>>>>>> JR Hospital, Headington, OX3 9DU, UK >>>>>>>> +44 (0) 1865 222545 (fax 717) >>>>>>>> www.fmrib.ox.ac.uk/~saad >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> Dr. med. Markus Gschwind, M.D. >>>>>>> Laboratory for Neurology and Imaging of Cognition >>>>>>> Dept of Neurosciences >>>>>>> University Medical Center (CMU) >>>>>>> 1 Michel-Servet - 1211 GENEVA - CH >>>>>>> >>>>>>> Tel 0041 (0) 22 379 5324 >>>>>>> Fax 0041 (0) 22 379 5402 >>>>>>> email: [log in to unmask] >>>>>>> http://labnic.unige.ch <http://labnic.unige.ch/> >>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> Dr. med. Markus Gschwind, M.D. >>>>>> Laboratory for Neurology and Imaging of Cognition >>>>>> Dept of Neurosciences >>>>>> University Medical Center (CMU) >>>>>> 1 Michel-Servet - 1211 GENEVA - CH >>>>>> >>>>>> Tel 0041 (0) 22 379 5324 >>>>>> Fax 0041 (0) 22 379 5402 >>>>>> email: [log in to unmask] >>>>>> http://labnic.unige.ch <http://labnic.unige.ch/> >>>>>> >>>>>> Saad Jbabdi >>>>>> Oxford University FMRIB Centre >>>>>> JR Hospital, Headington, OX3 9DU, UK >>>>>> +44 (0) 1865 222545 (fax 717) >>>>>> www.fmrib.ox.ac.uk/~saad >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>> >>>> >>> >> >> >> >> -- >> David A Gutman, M.D. Ph.D. >> Department of Psychiatry & Behavioral Sciences >> Emory University School of Medicine >> > -- David A Gutman, M.D. Ph.D. Department of Psychiatry & Behavioral Sciences Emory University School of Medicine