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On Thu, Oct 31, 2013 at 3:57 PM, fMRI <[log in to unmask]> wrote: > Donald, > > What I meant by labeling is for example if I want to use an automated > labeling software such as AAL or Anatomy or Peak_nii, they all require a > T-map instead. So I can not labeling the conjunction map using these > software, I think. > Peak_nii does not require a t-map. > > > I also found this > https://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind04&L=SPM&P=R187333 > It is about one way anova. So mu question is would my case be similar to > their case? The only difference is that they compare conjunction within > four conditions I think. > This approach is not valid. You cannot get the correct condition effects from the model with multiple conditions. While people did this in the past, its been shown to be a flawed approach as you have violated the assumption of the model. > > Regards, > > AS > > On 31 Oct 2013, at 07:40 pm, "MCLAREN, Donald" <[log in to unmask]> > wrote: > > >> >> The only problem that I could face might be labeling the common areas. Is >> there anyway of labeling bin maps of 1s? >> > > You can use imcalc to convert the thresholded t-map to 1s and 0s with the > equation: i1>0. > > When you add the maps together: > Voxels with a value of 1 will have only task effect 1, voxels with a value > of 2 will only have task effect 2, voxels with a value of 3 have both tasks > effects (aka the conjunction). > > > >> >> Is this an accepted way of reporting it? >> > > Yes. > > >> >> The other two questions that I have are: >> >> 1- can the conjunction analysis be done t the subject level and then do >> it at a group level? >> > > If you do it at the first-level, there is no way to bring the conjunction > map to the group level. You could ask how many subject show the conjunction > though. > > >> >> 2- if I do a one-sample t-tests of con images that are repeated >> measurements ( 2 from each subject), can I correct for non sphericity here >> ? Would this be correct? >> > > No. It would not be correct. one-sample t-tests can only have 1 image per > subject. If you have more than one image per subject you have violated the > assumption of the one-sample t-test. > >> >> >> Regards, >> >> AS >> >> On 31 Oct 2013, at 07:21 pm, "MCLAREN, Donald" <[log in to unmask]> >> wrote: >> >> Aser, >> >> You can't do a conjunction contrast at the group level because SPM can't >> give you the between-subject effects if you have multiple images per >> subject in the model. However, if you want to compute the conjunction, you >> could do 2 one-sample t-tests and then threshold each map, convert the >> thresholded maps to 1s and zeros, then use imcalc to determine the overlap >> with the equation: i1+2.*i2. The resulting image will have a value of 3 in >> any voxel that is common at the group level. >> >> Hope this helps, >> >> Best Regards, Donald McLaren >> ================= >> D.G. McLaren, Ph.D. >> Research Fellow, Department of Neurology, Massachusetts General Hospital >> and >> Harvard Medical School >> Postdoctoral Research Fellow, GRECC, Bedford VA >> Website: http://www.martinos.org/~mclaren >> Office: (773) 406-2464 >> ===================== >> This e-mail contains CONFIDENTIAL INFORMATION which may contain PROTECTED >> HEALTHCARE INFORMATION and may also be LEGALLY PRIVILEGED and which is >> intended only for the use of the individual or entity named above. If the >> reader of the e-mail is not the intended recipient or the employee or >> agent >> responsible for delivering it to the intended recipient, you are hereby >> notified that you are in possession of confidential and privileged >> information. Any unauthorized use, disclosure, copying or the taking of >> any >> action in reliance on the contents of this information is strictly >> prohibited and may be unlawful. If you have received this e-mail >> unintentionally, please immediately notify the sender via telephone at >> (773) >> 406-2464 or email. >> >> >> On Thu, Oct 31, 2013 at 12:32 PM, fMRI <[log in to unmask]> wrote: >> >>> Hello all, >>> >>> I would like to know how I can do a conjunction analysis at the group >>> level. >>> >>> I have two contrast images from each subject. >>> >>> Can I do conjunction contrast to see the common effect at the group >>> level? If yes how can I do it practically? >>> >>> Regards, >>> >>> Aser >> >> >> >